Thirdstage's Blog

Exception Handling of EJB

2011-11-22T20:07:00.004+09:00

EJB 2.1

from Chapter 18. Exception Handling of Enterprise JavaBeans Specification Version 2.1

Exceptions from a Session or Entity Bean’s Business Methods

EJB 3.0

from Chapter 14. Exception Handling of Enterprise JavaBeans Specification Version 3.0

Exceptions from a Session Bean’s Business Interface Methods

Using SyntaxHighlighter in Redmine

2011-10-20T21:05:00.014+09:00

Redmine provides built-in syntax highlighting based on CodeRay (for this, refer here). But it is not so much powerful as leading libraries such as SyntaxHighlighter.

You can use SyntaxHighlighter with Redmine by simply modifying one template file in the Redmine. The file to modify, base.rhtml is a template file specifying the layout of most pages and located at the following position.

The default contents of base.rhtml is like followings.

You can add a few header elements for styles and scripts to install SyntaxHighlighter like the following.

You should restart Redmine to apply the change of template. When loading Redmine using Apache HTTP server, just restart Apache HTTP server.

For more about SyntaxHighlighter refer its homepage at http://alexgorbatchev.com/SyntaxHighlighter/

Guildelines for Multi-moduled Maven Project

2011-10-13T14:55:00.022+09:00

Guildelines for Multi-moduled Maven Project

Separate parent project from container project.

Define properties in the parent POM file as possible.

Define the following properties explicitly for clearness and control.

Encoding related properties whose default value are dependent on platform.

project.build.sourceEncoding
project.reporting.outputEncoding

Properties to skip situationally unnecessary long running goals.

skipTests
maven.javadoc.skip
maven.deploy.skip
checkstyle.skip

Properties to run maven more stable way.

dependency.locations.enabled : refer If your maven site build is too slow

Paths for executable programs external to Maven

graphviz.home

Define all plugins in the `<pluginManagement>` element of parent POM file.

Don't specify version to plugin definitions in child POM files.

Define repositories in the parent POM file as possible.

Define plugins to analyze or diagnose the sources or resources of the project as a reporting plugin as possible.

Start values for path with `${project.basedir}`, `${project.build.directory}`, `${project.build.outputDirectory}` or so on

When just specifying relative path such as 'target/classes', the result directory could be different if you build the project from the enclosing project in multi-module case.
If you specify the path with leading ${project.build.directory}, the resulting directory always would be one that is calculated with the current POM's project.

Use resources in `target/classes` not in `src/main/resources`, considering resource filtering.

Sample of Parent POM

This is the real sample of parent POM I am using.

Frameworks, Libraries, Tools, and Utilities

2011-10-10T13:28:00.030+09:00

Frameworks

Logging

log4jdbc : http://code.google.com/p/log4jdbc/
a Java JDBC driver that can log SQL and/or JDBC calls (and optionally SQL timing information) for other JDBC drivers using the Simple Logging Facade For Java (SLF4J) logging system.

Templating

FreeMarker : http://freemarker.sourceforge.net/
a "template engine"; a generic tool to generate text output (anything from HTML to autogenerated source code) based on templates.

HTML/CSS

Compass : http://compass-style.org/
open-source CSS Authoring Framework.

Libraries

JavaScript

Datejs : http://code.google.com/p/datejs/
open source JavaScript Date library for parsing, formatting and processing.
SyntaxHighlighter : http://alexgorbatchev.com/SyntaxHighlighter/
a fully functional self-contained code syntax highlighter developed in JavaScript.

Expression Language

Java Expression Language (JEXL) : http://commons.apache.org/jexl/
a library intended to facilitate the implementation of dynamic and scripting features in applications and frameworks written in Java.

Tools

Java Source Analysis

Sonar : http://www.sonarsource.org/
Open platform to manage code quality.
JDepend : http://www.clarkware.com/software/JDepend.html
Traverses Java class file directories and generates design quality metrics for each Java package.
- JDepend 2.9.1 API : http://mcs.une.edu.au/doc/javadoc/jdepend-2.9.1/
Checkstyle : http://checkstyle.sourceforge.net/
Development tool to help programmers write Java code that adheres to a coding standard.

Java Performance Monitoring

VisualVM : http://visualvm.java.net/
Visual tool integrating several commandline JDK tools and lightweight profiling capabilities.

Java Dump Analysis

IBM HeapAnalyzer : https://www.ibm.com/developerworks/community/groups/service/html/communityview?communityUuid=4544bafe-c7a2-455f-9d43-eb866ea60091
Analyzes Java heap dumps by parsing the Java heap dump, creating directional graphs, transforming them into directional trees, and executing the heuristic search engine.
IBM Thread and Monitor Dump Analyzer for Java : https://www.ibm.com/developerworks/community/groups/service/html/communityview?communityUuid=2245aa39-fa5c-4475-b891-14c205f7333c
Analyzes javacore and diagnoses monitor locks and thread activities in order to identify the root cause of hangs, deadlocks, and resource contention or monitor bottlenecks.
Thread Dump Analyzer : http://java.net/projects/tda
Analyzes Thread Dumps of Sun, SAP and JRockit (partial).
Eclipse Memory Analyzer : http://www.eclipse.org/mat/
Fast and feature-rich Java heap analyzer that helps you find memory leaks and reduce memory consumption.

Web Development

Firebug : http://getfirebug.com/
Edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
JSLint : http://www.jslint.com/
a JavaScript program that looks for problems in JavaScript programs.

SQL Client/Database Management

SQuirreL SQL Client : http://www.squirrelsql.org/
A graphical Java program that will allow you to view the structure of a JDBC compliant database, browse the data in tables, issue SQL commands etc.
IBM Data Studio : http://www-01.ibm.com/software/data/optim/data-studio/
- Provides database developers and DBAs an integrated, modular environment for productive administration of DB2 for Linux, UNIX and Windows.
- Provides collaborative database development tools for DB2, Informix, Oracle, and Sybase at no charge.
Oracle SQL Developer : http://www.oracle.com/technetwork/developer-tools/sql-developer/

ETL

Scriptella : http://scriptella.javaforge.com/
An open source ETL (Extract-Transform-Load) and script execution tool written in Java.

Utilities

PC Diagnostic and Recovery

Hiren's BootCD : http://www.hiren.info/pages/bootcd
A bootable software CD containing a number of diagnostic programs such as partitioning agents, system performance benchmarks, disk cloning and imaging tools, data recovery tools, MBR tools, BIOS tools, and many others for fixing various computer problems.
For download and more information, refer fan & discussion site.

File Synchronization

rsync : http://rsync.samba.org/
An open source utility that provides fast incremental file transfer.
For front-end soft-wares or solutions based on rsync, refer http://en.wikipedia.org/wiki/Rsync#Solutions_using_Rsync.

Readings on Business Applications

2011-09-16T20:33:00.003+09:00

Data-warehouse, BI

Introduction to OLAP

Tips on Regex

2011-07-23T01:52:00.022+09:00

Readings : References, Tutorials and Articles

Know your regular expressions from developerWorks

Special Characters of ERE (Extended Regular Expression)

from Regular Expressions in Single UNIX Specification

An ERE special character has special properties in certain contexts. Outside those contexts, or when preceded by a backslash, such a character is an ERE that matches the special character itself. The extended regular expression special characters and the contexts in which they have their special meaning are:

. \ [ (

The period, left-bracket, backslash and left-parenthesis are special except when used in a bracket expression. Outside a bracket expression, a left-parenthesis immediately followed by a right-parenthesis produces undefined results.

)

The right-parenthesis is special when matched with a preceding left-parenthesis, both outside a bracket expression.

* + ? {

The asterisk, plus-sign, question-mark and left-brace are special except when used in a bracket expression (see RE Bracket Expression ). Any of the following uses produce undefined results:

if these characters appear first in an ERE, or immediately following a vertical-line, circumflex or left-parenthesis.
if a left-brace is not part of a valid interval expression.

|

The vertical-line is special except when used in a bracket expression. A vertical-line appearing first or last in an ERE, or immediately following a vertical-line or a left-parenthesis, or immediately preceding a right-parenthesis, produces undefined results.

^

The circumflex is special when used:

as an anchor
as the first character of a bracket expression

$

The dollar sign is special when used as an anchor.

Regex with Java

You can find the most proper information to use regex with Java in the API documentation of java.util.regex.Pattern class

http://download.oracle.com/javase/1.5.0/docs/api/java/util/regex/Pattern.html

Formal rules for bracket expression

Bracket expressions such as [0-9a-zA-Z], [^0-9a-zA-Z], or [0-9a-zA-Z.?*+-] are kind of different from normal expressions. One of the most important differences is metacharacters or special characters. Including that, more formal detailed description for bracket expression can be found in the following

Capturing, Grouping and Backreferences

Backreferences in Regular Expressions

NOT operator in Regex

Nested pairs search

Lookaround : lookahead and lookbehind

Lookahead and Lookbehind Zero-Width Assertions

Greedy, Reluctant, or Possessive Quantifiers

Quantifiers in The Java Tutorials

Servlet, JSP, JSTL, JSF and EL Compatibility

2011-07-15T15:54:00.009+09:00

Servlet and JSP Versions

Servlet ver.	Released at	JSP ver.	Java EE ver.	Java SE ver.
Servlet 3.0	Dec. 2009	JSP 2.2	Java EE 6	Java SE 6
Servlet 2.5	Sep. 2005	JSP 2.1	Java EE 5	Java SE 5
Servlet 2.4	Nov. 2003	JSP 2.0	J2EE 1.4	J2SE 1.3
Servlet 2.3	Aug. 2001	JSP 1.2	J2EE 1.3	J2SE 1.2
Servlet 2.2	Aug. 1999	JSP 1.1	J2EE 1.2	J2SE 1.2

JSTL Compatibility

JSTL ver.	Released at	JSP ver.	Servlet ver.
JSTL 1.2	May 2006	JSP 2.1	Servlet 2.5
JSTL 1.1	Nov. 2003	JSP 2.0	Servlet 2.4
JSTL 1.0	Jun. 2002	JSP 1.2	Servlet 2.3

JSF Compatibility

JSF ver.	Released at	JSP ver.	Servlet ver.	JSTL ver.
JSF 2.1	Nov. 2010	JSP 2.1	Servlet 2.5	JSTL 1.2
JSF 2.0	Jun. 2009	JSP 2.1	Servlet 2.5	JSTL 1.2
JSF 1.2	May 2006	JSP 2.1	Servlet 2.5	JSTL 1.2
JSF 1.1	May 2004	JSP 1.2	Servlet 2.3	JSTL 1.0
JSF 1.0	Mar. 2004	JSP 1.2	Servlet 2.3	JSTL 1.0

EL Compatibility

EL ver.	Released at	JSP ver.	JSF ver.
EL 2.2	Dec. 2009	JSP 2.2	JSF 2.0
EL 2.1	May 2006	JSP 2.1	JSF 1.2

References

My Styles

2011-07-13T10:55:00.002+09:00

Styles for Redmine of my team

Access InitialContext by Application Server

2011-07-10T02:46:00.003+09:00

Readings

JBoss

Naming on JBoss 4

WebLogic

Programming WebLogic 8.1 JNDI

Investgating InitialContext

2011-07-01T00:33:00.008+09:00

You can get all name-class pairs under InitialContext of your application server using the following simple code containing recursive call.

Concurrency and Transaction in Oracle

2011-06-27T19:26:00.005+09:00

Locks Obtained by DML Statements in Oracle

from Oracle Database Concepts

Oracle provides data concurrency and integrity between transactions using its locking mechanisms. Because the locking mechanisms of Oracle are tied closely to transaction control, application designers need only define transactions properly, and Oracle automatically manages locking.

Keep in mind that Oracle locking is fully automatic and requires no user action. Implicit locking occurs for all SQL statements so that database users never need to lock any resource explicitly. Oracle's default locking mechanisms lock data at the lowest level of restrictiveness to guarantee data integrity while allowing the highest degree of data concurrency.

The purpose of a DML lock (data lock) is to guarantee the integrity of data being accessed concurrently by multiple users. DML locks prevent destructive interference of simultaneous conflicting DML or DDL operations. DML statements automatically acquire both table-level locks and row-level locks.

The following table summarize how Oracle automatically locks data on behalf of different DML operations.

DML Statement	Row Locks	Table Locks
SELECT ... FROM table
INSERT INTO table ...	Exclusive Row Locks	Row Exclusive Table Locks
UPDATE table ...	Exclusive Row Locks	Row Exclusive Table Locks
DELETE FROM table ...	Exclusive Row Locks	Row Exclusive Table Locks
SELECT ... FROM table ... FOR UPDATE OF ...	Exclusive Row Locks	Row Share Table Locks

Exclusive Row Lock
- A transaction acquires an exclusive row lock for each individual row modified by one of the following statements: INSERT, UPDATE, DELETE, and SELECT with the FOR UPDATE clause.
- A modified row is always locked exclusively so that other transactions cannot modify the row until the transaction holding the lock is committed or rolled back.
Row Exclusive Table Locks
- A row exclusive table lock generally indicates that the transaction holding the lock has made one or more updates to rows in the table.
- A row exclusive table lock held by a transaction allows other transactions to query, insert, update, delete, or lock rows concurrently in the same table. Therefore, row exclusive table locks allow multiple transactions to obtain simultaneous row exclusive and row share table locks for the same table.
- A row exclusive table lock held by a transaction prevents other transactions from manually locking the table for exclusive reading or writing.
Row Share Table Locks
- A row share table lock indicates that the transaction holding the lock on the table has locked rows in the table and intends to update them.
- A row share table lock held by a transaction allows other transactions to query, insert, update, delete, or lock rows concurrently in the same table.
- A row share table lock held by a transaction prevents other transactions from exclusive write access to the same table using only LOCK TABLE table IN EXCLUSIVE MODE statement.

Locking for `SELECT` statement

A query acquires no data locks. Therefore, other transactions can query and update a table being queried, including the specific rows being queried. Because queries lacking FOR UPDATE clauses do not acquire any data locks to block other operations, such queries are often referred to in Oracle as nonblocking queries.
A query does not have to wait for any data locks to be released; it can always proceed. (Queries may have to wait for data locks in some very specific cases of pending distributed transactions.)

Locking for `INSERT, UPDATE, DELETE`, and `SELECT ... FOR UPDATE` statement

The transaction that contains a DML statement acquires exclusive row locks on the rows modified by the statement. Other transactions cannot update or delete the locked rows until the locking transaction either commits or rolls back.
The transaction that contains a DML statement does not need to acquire row locks on any rows selected by a subquery or an implicit query, such as a query in a WHERE clause. A subquery or implicit query in a DML statement is guaranteed to be consistent as of the start of the query and does not see the effects of the DML statement it is part of.
A query in a transaction can see the changes made by previous DML statements in the same transaction, but cannot see the changes of other transactions begun after its own transaction.
In addition to the necessary exclusive row locks, a transaction that contains a DML statement acquires at least a row exclusive table lock on the table that contains the affected rows. If the containing transaction already holds a share, share row exclusive, or exclusive table lock for that table, the row exclusive table lock is not acquired. If the containing transaction already holds a row share table lock, Oracle automatically converts this lock to a row exclusive table lock.

Tips on MyBatis

2011-05-20T23:19:00.006+09:00

Thread-safety of `SqlSession`

Two main implementation of SqlSession interface have opposite semantics in thread-safety.
org.apache.ibatis.session.defaults.DefaultSqlSession is not thread-safe and so should not be shared among threads. But, org.mybatis.spring.SqlSessionTemplate provided to used with Spring framework is thread-safe.

Two implementations can not replace each other. So, the POJO into which SqlSessionTemplate is expected to be injected by Spring IoC container will not work correctly with other implementation of SqlSession in non-Spring environment. Can this be called POJO ?

I think this is somewhat confusing feature. I'm not sure thead-safety is dealt with interface scope of respective implmentation scope. SqlSession is in the heart of MyBatis, and so it seems desirable to have more clear semantics.

General method to check properties of an object using Spring EL

2011-04-27T00:35:00.007+09:00

Spring 3.0 introduced powerful expression language (SpEL). We can make a simple utility method to check the properties of an object in any type using SpEL

The following is simple sample.

Note that the method consists of only two line. With the following unit test sample, you can imagine the robustness of the above method.

Simple Code Patterns in Java

2011-04-26T10:12:00.016+09:00

Typical code pattern for Regex API

The simplest code pattern for when a regular expression is used just once is to use static Pattern.matches method.

boolean b = Pattern.matches("a*b", "aaaaab");

When using a expression several times, it is better to use compiled pattern object considering performance.

Pattern p = Pattern.compile("a*b");
boolean b1 = p.matcher("aaaaab").matches();
boolean b2 = p.matcher("bbbbb").matches();

Lazy initialization of field

Lazy initialization of instance field using double-checked locking

Prior to JDK 1.5, double-checked locking is not safe with Java because the reordering of object publication and initialization can not be controlled. But as of JDK 1.5, volatile is specified not to be reordered, so it become possible to use safely double-checked locking with volatile field.

A typical code would be like this :

public class Worker{

   private volatile Resource resource = null; //creating resource is expensive
   private final Object lock = new Object();

   public Resource getResource(){
      Resource r = resource;
      if(r == null){ //first check
         synchronized(lock){
            r = resource;
            if(r == null){ //second check
               resource = r = new Resource();
            }
         }
      }
      return r;
   }
   
   ...
}

In above sample code, note that the lock object is define to be final, because reference on non final field can change any time.^[5]

Lazy initialization of static field using initialization on demand holder class

On behalf of the characteristics of class loading and static initialization, static field can be safely lazy initialized using holder class without locking.

JVM load classes in lazy way and JVM run static initilizers at class initilization time which is after class loading but before the class is used by any thread. So, the static holder class having static field like the below would be lazy initialized in safe way.

public class Worker{

   private static class ResourceHolder{
      public static Resource resource = new Resource();
   }

   public static Resource getResource(){
      return ResourceHolder.resource;
   }
   
   ...
}

More codes

`CommonAnnotationBeanPostProcessor.findResourceMetadata` method of Spring framework

The following code from Spring framework uses double-checked locking for non-volatile field.

Is it safe ?

Assuming ConcurrentHashMap.put method may not be so complicated to expose stale values to threads and the local codes inside second check block (inner if clause checking metadata == null) would not be reordered with ConcurrentHashMap.put method execution, the below code could be almost safe ?

package org.springframework.context.annotation;

public class CommonAnnotationBeanPostProcessor extends ...{

  ...
  private transient final Map<Class<?>, InjectionMetadata> injectionMetadataCache =
  new ConcurrentHashMap<Class<?>, InjectionMetadata>();

  ...

  private InjectionMetadata findResourceMetadata(final Class clazz) {
    // Quick check on the concurrent map first, with minimal locking.
    InjectionMetadata metadata = this.injectionMetadataCache.get(clazz);
    if (metadata == null) {
      synchronized (this.injectionMetadataCache) {
        metadata = this.injectionMetadataCache.get(clazz);
        if (metadata == null) {
          final InjectionMetadata newMetadata = new InjectionMetadata(clazz);
          ReflectionUtils.doWithFields(clazz, new ReflectionUtils.FieldCallback() {
            public void doWith(Field field) {
              if (webServiceRefClass != null 
                  && field.isAnnotationPresent(webServiceRefClass)) {
                if (Modifier.isStatic(field.getModifiers())) {
                  throw new IllegalStateException("@WebServiceRef annotation is not supported on static fields");
                }
                newMetadata.addInjectedField(new WebServiceRefElement(field, null));
              }
              else if (ejbRefClass != null 
                  && field.isAnnotationPresent(ejbRefClass)) {
                if (Modifier.isStatic(field.getModifiers())) {
                  throw new IllegalStateException("@EJB annotation is not supported on static fields");
                }
                newMetadata.addInjectedField(new EjbRefElement(field, null));
              }
              else if (field.isAnnotationPresent(Resource.class)) {
                if (Modifier.isStatic(field.getModifiers())) {
                  throw new IllegalStateException("@Resource annotation is not supported on static fields");
                }
                if (!ignoredResourceTypes.contains(field.getType().getName())) {
                  newMetadata.addInjectedField(new ResourceElement(field, null));
                }
              }
            }
          });
          ReflectionUtils.doWithMethods(clazz, new ReflectionUtils.MethodCallback() {
            public void doWith(Method method) {
              if (webServiceRefClass != null 
                  && method.isAnnotationPresent(webServiceRefClass) 
                  &&
                  method.equals(ClassUtils.getMostSpecificMethod(method, clazz))) {
                if (Modifier.isStatic(method.getModifiers())) {
                  throw new IllegalStateException("@WebServiceRef annotation is not supported on static methods");
                }
                if (method.getParameterTypes().length != 1) {
                  throw new IllegalStateException("@WebServiceRef annotation requires a single-arg method: " + method);
                }
                PropertyDescriptor pd = BeanUtils.findPropertyForMethod(method);
                newMetadata.addInjectedMethod(new WebServiceRefElement(method, pd));
              }
              else if (ejbRefClass != null && method.isAnnotationPresent(ejbRefClass) &&
                  method.equals(ClassUtils.getMostSpecificMethod(method, clazz))) {
                if (Modifier.isStatic(method.getModifiers())) {
                  throw new IllegalStateException("@EJB annotation is not supported on static methods");
                }
                if (method.getParameterTypes().length != 1) {
                  throw new IllegalStateException("@EJB annotation requires a single-arg method: " + method);
                }
                PropertyDescriptor pd = BeanUtils.findPropertyForMethod(method);
                newMetadata.addInjectedMethod(new EjbRefElement(method, pd));
              }
              else if (method.isAnnotationPresent(Resource.class) &&
                  method.equals(ClassUtils.getMostSpecificMethod(method, clazz))) {
                if (Modifier.isStatic(method.getModifiers())) {
                  throw new IllegalStateException("@Resource annotation is not supported on static methods");
                }
                Class[] paramTypes = method.getParameterTypes();
                if (paramTypes.length != 1) {
                  throw new IllegalStateException("@Resource annotation requires a single-arg method: " + method);
                }
                if (!ignoredResourceTypes.contains(paramTypes[0].getName())) {
                  PropertyDescriptor pd = BeanUtils.findPropertyForMethod(method);
                  newMetadata.addInjectedMethod(new ResourceElement(method, pd));
                }
              }
            }
          });
          metadata = newMetadata;
          this.injectionMetadataCache.put(clazz, metadata);
        }
      }
    }
    return metadata;
  }    

  ...
}

Tips on Spring

2011-04-24T19:18:00.028+09:00

Readings : References, Tutorials, Articles

Schemas for XML based configuration

Name	Location	Role
beans	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd	defines the elements to define beans.
context	http://www.springframework.org/schema/context/spring-context-3.0.xsd	defines the configuration elements for the Spring Framework's application.
tx	http://www.springframework.org/schema/tx/spring-tx-3.0.xsd	defines the elements used in the Spring Framework's declarative transaction management infrastructure.
aop	http://www.springframework.org/schema/aop/spring-aop-3.0.xsd	defines the configuration elements for the Spring Framework's AOP support.
mvc	http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd	defines elements to configure the annotation-driven Spring MVC Controller programming model
jee	http://www.springframework.org/schema/jee/spring-jee-3.0.xsd	defines configuration elements for access to traditional Java EE components such as JNDI resources and EJB session beans.
jms	http://www.springframework.org/schema/jms/spring-jms-3.0.xsd	defines the configuration elements for the Spring Framework's JMS support.
jdbc	http://www.springframework.org/schema/jdbc/spring-jdbc-3.0.xsd	defines the configuration elements for the Spring Framework's embedded database support.

Configuring Dependency in Maven to Use Auto-detecting and Name-based Auto-wiring of Beans with Spring 3.0

(2011-04-24)

To apply both bean auto-detecting using streotype such as @Component, @Controller, @Services, or @Repository and name-based (auto) wiring using @Resource annotation, you should manually add cglib into the Maven dependency config.

So, the part of the pom.xml would like this :

    
     org.springframework
     spring-core
     3.0.5.RELEASE
     jar
     compile
    
    
     org.springframework
     spring-context
     3.0.5.RELEASE
     jar
     compile
    
    
     org.springframework
     spring-aop
     3.0.5.RELEASE
     jar
     compile
    
    
     org.springframework
     spring-web
     3.0.5.RELEASE
     jar
     compile
    
    
     org.springframework
     spring-webmvc
     3.0.5.RELEASE
     jar
     compile
    
    
     cglib
     cglib-nodep
     2.2
     jar
     compile

Note that you need not or should not add asm into your pom.xml. Adding asm make the behavior of the build very confusing to me.

Hibernate 3.x has explicit dependency on asm. So, when using both Spring 3.0 and Hibernate 3.x together, it may be very difficult to correctly configure the Maven dependencies.
For details on this, refere the following : http://blog.newsplore.com/2009/03/07/upgrading-to-spring-30

Configuring SqlMapClientFactoryBean

(2009-08-13)

SqlMapClientBean of springframework creates SqlMapClient with EXTERNAL transaction management by default and internally wrap the given data source to TransactionAwareDataSourceProxy.

So, the typical setup for iBATIS SqlMapClient bean in spring configuration would be like the following.

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
 <property name="driverClassName" value="oracle.jdbc.OracleDriver" />
 <property name="url" value="jdbc:oracle:thin:@127.0.0.1:1521:XE" />
 <property name="username" value="_user_" />
 <property name="password" value="_passwd_" />
 <property name="defaultAutoCommit" value="true" />
 <property name="maxActive" value="10" />
 <property name="maxIdle" value="10" />
 <property name="minIdle" value="0" />
 <property name="initialSize" value="10" />
</bean>

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
 <property name="dataSource" ref="dataSource" />
 <property name="defaultTimeout" value="120" />
</bean>
 
<tx:annotation-driven 
 transaction-manager="transactionManager"
 mode="proxy"
 proxy-target-class="true"
/>

<bean id="sqlMapClient" class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
 <description>default SqlMapClient bean for DAOs</description>
 <property name="configLocation" value="classpath:_pathto_/sql-map.xml" />
  
 <property name="dataSource" ref="dataSource" />
 <!-- Default setting is specified for clarity. -->
 <property name="useTransactionAwareDataSource" value="true"/>
 <!-- Default setting is specified for clarity. -->
 <property name="transactionConfigClass">
  <value type="java.lang.Class">com.ibatis.sqlmap.engine.transaction.external.ExternalTransactionConfig
 </property>

</bean>

At the above sample, the default setup for useTransactionAwareDataSource and transactionConfigClass properties is specified for clarity.

ExternalTransactionConfig would set the "SetAutoCommitAllowed" property of SqlMapClient to false, in contrast to the iBATIS default, to always keep the original autoCommit value as provided by the connection pool.

For more information, refer API documentation of SqlMapClientFactoryBean, specially setDataSource, setUseTransactionAwareDataSource, and setTransactionConfigClass methods.

Annotation Based JMX in Spring Framework 2.5

(2008-08-04)

In spring framework 2.5, to use annotation based JMX

The position of the JMX bean definition in bean config
The type of proxy

is important.

Readings on Information Technoloby

2011-04-20T13:27:00.121+09:00

Computer Science/Programming

Type System in Wikipedia

Java SE

Java EE

Be careful with Singleton Session Bean (01/31/2010)
J2EE Transaction Frameworks: Building the Framework (04/26/2001)

Spring

AOP

Testing Frameworks

Logging Frameworks

Templating Frameworks

FreeMarker

HTML

Named Entity

CSS

JavaScript

jQuery

jQuery Plugins

jsTree
a javascript based, cross browser tree component. It is packaged as a jQuery plugin.
jQuery plugin: Treeview

jQuery plugin: Validation

XML

RELAX NG

Database

Sybase

Wiki

Lightweight markup conversion using Eclipse WikiText.
WikiText provides Ant tasks to convert markups to HTML, DocBook, Eclipse help or XSL-FO
Restarting Redmine without restarting Apache

Textile

UNIX, Linux

Cygwin User's Guide

Shell

Bash: about .bashrc, .bash_profile, .profile, /etc/profile, etc/bash.bashrc and others

Diagrams for Spring Framework

2011-04-15T02:25:00.012+09:00

Resources

Task Executors

Tips on MySQL

2011-03-29T12:38:00.007+09:00

Readings and References

MySQL 5.0 : server option and variable reference

Notable Options

MySQL 5.0

Maybe the most common options to customize are storage engine, character set, location of data and log files with your MySQL instance.

You can change location of your data files using datadir option. But you should copy the entire contents of the data directory under the installation of your MySQL to the new location.
Default storage engine and character set for your schemas and tables can be specified using default-storage-engine and character-set-server options.
In case of InnoDB, you can specifiy the location of log files and their archives using innodb_log_group_home_dir and innodb_log_arch_dir options.

datadir = D:\home\mysql\5.0\data/
default-storage-engine = innodb
lower_case_table_names = 2

character-set-server = utf8
character-set-filesystem = utf8
collation-server = utf8_general_ci

innodb_data_file_path = ibdata1:30M:autoextend
innodb_log_group_home_dir = D:\home\mysql\5.0\log/
innodb_log_arch_dir = D:\home\mysql\5.0\log/

Naming Schema Namespace and Location

2011-03-18T09:32:00.016+09:00

Samples on Well-known Schemas

Schema for	Schema file	Applied to	Namespace	Location
J2EE web application 2.4 deployment descriptor	web-app_2_4.xsd	web.xml	http://java.sun.com/xml/ns/j2ee	http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd
J2EE web application 2.5 deployment descriptor	web-app_2_4.xsd	web.xml	http://java.sun.com/xml/ns/javaee	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd
EJB 2.1 deployment descriptor	ejb-jar_2_1.xsd	ejb-jar.xml	http://java.sun.com/xml/ns/j2ee	http://java.sun.com/xml/ns/j2ee/ejb-jar_2_1.xsd
EJB 3.0 deployment descriptor	ejb-jar_3_0.xsd	ejb-jar.xml	java.sun.com/xml/ns/javaee	http://java.sun.com/xml/ns/javaee/ejb-jar_3_0.xsd
Spring 2.5 IoC configuration	spring-beans-2.5.xsd	...	http://www.springframework.org/schema/beans	http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
Spring 3.0 IoC configuration	spring-beans-3.0.xsd	...	http://www.springframework.org/schema/beans	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
Spring 2.5 AOP configuration	spring-aop-2.5.xsd	...	http://www.springframework.org/schema/aop	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
Spring 3.0 AOP configuration	spring-aop-3.0.xsd	...	http://www.springframework.org/schema/aop	http://www.springframework.org/schema/aop/spring-aop-3.0.xsd

Related Element and Attribute

Example : Spring 3.0 IoC configuration

Schema : spring-beans-2.5.xsd

<xsd:schema targetNamespace="http://www.springframework.org/schema/beans">
  <xsd:import namespace="http://www.w3.org/XML/1998/namespace"/>
...
</xsd:schema>

XML

<beans xmlns="http://www.springframework.org/schema/beans" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:aop="http://www.springframework.org/schema/aop" 
 xsi:schemaLocation="
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"
 default-lazy-init="false">
...
</beans>

Example : EJB 3.0 deployment descriptor

Schema : ejb-jar_3_0.xsd

<xsd:schema xmlns="http://www.w3.org/2001/XMLSchema"
    targetNamespace="http://java.sun.com/xml/ns/javaee"
    xmlns:javaee="http://java.sun.com/xml/ns/javaee"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified"
    attributeFormDefault="unqualified"
    version="3.0">
...
</xsd:schema>

XML

<ejb-jar xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/ejb-jar_3_0.xsd"
    version="3.0">
...
</ejb-jar>

Readings on Eclipse Programming

2011-03-15T00:11:00.014+09:00

Overall

Help Center

Development Conventions and Guidelines

Tutorials & Articles

Eclipse resources at eclipse.org

Platform & RCP

API

Tutorials & Articles

EMF

API

EMF 2.6 API Specification

Tutorials & Articles

Eclipse Modeling Framework(EMF) Tutorial by Lars Vogel
openArchitectureWare User Guide
contains EMF tutorial, Xtext tutorial, samples and so on.
EMF Tutorial on Robowiki

GEF

Tutorials & Articles

Eclipse Zest Tutorial by Lars Vogel

Mylyn

Tutorials & Articles

Generic Web Templates Connector

Tips on Security with Java

2011-03-09T14:09:00.006+09:00

Symmetric encryption based Encryptor/Decryptor

Most of cases with moderate requirement on security, I think, private key based encryption is well-suited. Non-secure encoding such as Base64 or Quoted-Printable encoding seems dangerous but, public key based encryption seems too costly.
I couldn't find well-shaped and trusty library on private key based encryption until recently. Today I have found such a one within Spring Security.

Spring Security provides

private key based bytes encryptor, text encryptor
factory class for encryptors
key generators to provide keys to encryptor
password encoders which use one way encoding algorithm such as hashing.

The API is not so complicated as javax.crpyto but enough for general purpose.

For more details, you can refer the followings.

Constructing BigDecimal

2010-12-28T17:26:00.004+09:00

The code is :

public void testDoubleToBigDecimalViaString(){
  
  double d = 0.1;
  double e = 0.11;
  double f = e - d;
//  MathContext mc1 = MathContext.DECIMAL32;
//  MathContext mc2 = MathContext.UNLIMITED;
  MathContext mc1 = new MathContext(7);
  MathContext mc2 = new MathContext(34);
  
  BigDecimal bd1 = new BigDecimal(d);
  BigDecimal bd2 = new BigDecimal(String.valueOf(d));
  
  System.out.println("bd1 = " + bd1.toString());
  System.out.println("bd2 = " + bd2.toString());

  BigDecimal bd9 = new BigDecimal(d, mc1);
  BigDecimal bd10 = new BigDecimal(String.valueOf(d), mc1);
  
  System.out.println("bd9 = " + bd9.toString());
  System.out.println("bd10 = " + bd10.toString());

  BigDecimal bd11 = new BigDecimal(d, mc2);
  BigDecimal bd12 = new BigDecimal(String.valueOf(d), mc2);
  
  System.out.println("bd11 = " + bd11.toString());
  System.out.println("bd12 = " + bd12.toString());
  
  
  
  BigDecimal bd3 = new BigDecimal(f);
  BigDecimal bd4 = new BigDecimal(String.valueOf(f));
  
  System.out.println("bd3 = " + bd3.toString());
  System.out.println("bd4 = " + bd4.toString());

  BigDecimal bd5 = new BigDecimal(f, mc1);
  BigDecimal bd6 = new BigDecimal(String.valueOf(f), mc1);
  
  System.out.println("bd5 = " + bd5.toString());
  System.out.println("bd6 = " + bd6.toString());

  BigDecimal bd7 = new BigDecimal(f, mc2);
  BigDecimal bd8 = new BigDecimal(String.valueOf(f), mc2);
  
  System.out.println("bd7 = " + bd7.toString());
  System.out.println("bd8 = " + bd8.toString());
}

The result with Sun JDK 1.6 is :


bd1 = 0.1000000000000000055511151231257827021181583404541015625
bd2 = 0.1
bd9 = 0.1000000
bd10 = 0.1
bd11 = 0.1000000000000000055511151231257827
bd12 = 0.1
bd3 = 0.00999999999999999500399638918679556809365749359130859375
bd4 = 0.009999999999999995
bd5 = 0.01000000
bd6 = 0.01000000
bd7 = 0.009999999999999995003996389186795568
bd8 = 0.009999999999999995

Thread Dump

2010-12-14T01:28:00.007+09:00

Generating Thread Dump

Sun JDK

The following is quoted from J2SE 5.0 Troubleshooting and Diagnostic Guide.

1.16 Ctrl-Break Handler

On Solaris or Linux the HotSpot VM will print a thread dump to the application's standard output if the Ctrl and \ keys are pressed. The thread dump consists of the thread stack for all Java threads in the VM. On Windows the equivalent key sequence is the Ctrl and Break keys. The thread dump doesn't terminate the application – it continues after the thread information is printed.
On Solaris and Linux a thread dump is also printed if the J2SE process receives a QUIT signal. So kill -QUIT <pid> causes the process with id <pid> to print a thread dump to its standard output.
In addition to the thread stacks, the ctrl-break handler also executes a deadlock detection algorithm. If any deadlocks are detected then it prints out additional information on each deadlocked thread.

IBM Java SDK

The following is quoted from IBM Java SDK Diagnostics Guide 6.

Chapter 25. Using Javadump

...

The signal for Linux, AIX and z/OS is SIGQUIT. Use the command kill -QUIT n to send the signal to a process with process id (PID) n. Alternatively, press CTRL+\ in the shell window that started Java.(CTRL+V on z/OS.)
The signal for AIX is SIGQUIT. Use the command kill -QUIT n to send the signal to a process with process id (PID) n. Alternatively, press CTRL+\ in the shell window that started Java.
In Windows, the dump is initiated by using CTRL+Break in the command window that started Java.
The signal for i5/OS is SIGQUIT. Use the command kill -QUIT n to send the signal to a process with process id (PID) n. The PID for a particular JVM can be found in the joblog for the job (JVAB56D: Java Virtual Machine is IBM Technology for Java. PID(x)), or using the "ps" command from qsh or an i5/OS PASE shell.
The JVM will continue operation after the signal has been handled.

Obtaining Clue on OOM(OutOfMemory) Error

OutOfMemoryError is one of the most terrible problems. To prevent it from occurring again, it is very important to identify the cause. The heap dump at the time of error maybe provide the most exact cause to the error. With JDK 1.5 or higher, you can use the following options with JVM to obtain the heap dump at the time when OutOfMemoryError ocurrs.


-XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=path-of-dump-to-generate

One thing that needs to be considered more is that the above options derive how much overhead or side effects. I don't have any idea about it, and so I have no confidence where the above options can be safely used in production environment. To confirm using in production environment, more thorough research is necessary.

HotSpot VM Tuning

2010-12-09T10:44:00.010+09:00

Articles

Tuning HotSpot Java virtual machines (Solaris & HP-UX) (from documentation of WebSphere 7.0)
Sun HotSpot JVM tuning parameters (Solaris and HP-UX) (from documentation of WebSphere 7.0)
My Favorite Hotspot JVM Flags

Identifying Current/Min/Max Size of Young and Old Generation

You can identify details of memory usage such as min./max. size of old generation, current size of eden space and current size young generation on a running VM instance using jstat command.

For example, the VM launched with the following option.


-Xms128m -Xmx256m -XX:MaxPermSize=256M -server -XX:+UseParallelGC -XX:NewRatio=2 -XX:SurvivorRatio=8

Shows the following information with jstat -gccapacity -h5 3680 5s.


C:\lang\jdk1.6\bin>jstat -gccapacity -h5 3680 5s
 NGCMN    NGCMX     NGC     S0C   S1C       EC      OGCMN      OGCMX       OGC         OC      PGCMN    PGCMX     PGC
    PC     YGC    FGC
 43648.0  87360.0  43648.0 4480.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     48     3
 43648.0  87360.0  43648.0 4480.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     48     3
 43648.0  87360.0  43648.0 4480.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     48     3
 43648.0  87360.0  43648.0 4480.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     48     3
 43648.0  87360.0  43648.0 4480.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     48     3
 NGCMN    NGCMX     NGC     S0C   S1C       EC      OGCMN      OGCMX       OGC         OC      PGCMN    PGCMX     PGC
    PC     YGC    FGC
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 NGCMN    NGCMX     NGC     S0C   S1C       EC      OGCMN      OGCMX       OGC         OC      PGCMN    PGCMX     PGC
    PC     YGC    FGC
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3
 43648.0  87360.0  43648.0 4352.0 4416.0  34752.0    87424.0   174784.0   116608.0   116608.0  16384.0 262144.0 103936.0
 103936.0     49     3

You can identify the above statistics in visual form using visualgc. visualgc is provided as a plugin of VisualVM.

References

Notable Principles of J2EE Specs

2010-12-08T10:19:00.023+09:00

Session Bean's Business Interface of EJB 3.x

from Enterprise JavaBeans Version 3.1 EJB Core Contracts and Requirements

The interface msut not extend the javax.ejb.EJBObject or javax.ejb.EJBLocalObject interface.
If the business interface is a remote business interface, the argument and return value must be a valid type for RMI/IIOP. The remote business interface is not required or expected to be a java.rmi.Remote interface. The throw clause should not include the java.rmi.RemoteException. The method of the business interface may only throw the java.rmi.RemoteException if the interface extends java.rmi.Remote.
The interface is allowed to have superinterfaces.
If the interface is a remote business interface, its method must not expose local interface types, timers or timer handles, or the managed collection classes that are used for EJB 2.1 entity beans with container-managed persistence as arguments or results.
The bean class must implement the interface or the interfaces must be designated as a local or remote business interface of the bean by means of the Local and Remote annotation or in the deployment descriptor. The following rules apply:
- If the bean does not expose any other client view (Local, Remote, Non-interface, 2.x Remote Home, 2.x Local Home, Web Service) and the bean class implements a single interface, that interface is assumed to be the business interface of the bean. This business interface will be a local interface unless the interface is designated as a remote business interface by use of Remote annotation on the bean class or interface or by means of the deployment descriptor.
- A bean class is permitted to have more than one interface. If a bean class has more than one interface-excluding the interface listed below-any business interface of the bean class must be explicitly designated as a business interface of the bean by means of the Local or Remote annotation on the bean class or interface or in the deployment descriptor.
- The following interfaces are excluded when determining whether the bean class has more than one interface: java.io.Serializable; java.io.Externalizable; any of the interfaces defined by javax.ejb package.
- The same business interface cannot be both a local and a remote business interface of the bean. It is also an error if the Local and/or Remote annotations are specified both on the bean class and on the referenced interface and the values differ.
- While it is expected that the bean class will typically implement its business interface(s), if the bean class uses annotations or the deployment descriptor to designate its business interface(s), it is not required that the bean class also be specified as implementing the interface(s).

Application Exception of EJB 3.x

from Enterprise JavaBeans Version 3.1 EJB Core Contracts and Requirements

Application exceptions that are checked exceptions may be defined as such by being listed in the throws clauses of the method of the bean's business interface, no-interface view, home interface, component interface, and web service endpoint. An application exception that is an unchecked exception is defined as an application exception by annotating it with the ApplicationException metadata annotation, or denoting it in the deployment descriptor with the application-exception element.

ApplicationException

rollback

true

application-exception

rollback

true

rollback

application-exception

rollback

ApplicationException

Specification for Exception Handling with EJB

System Exception with EJB 2.x

from Chapter 18. Exception Handling of Enterprise JavaBeans Specification Version 2.1

When bean method runs in the context of the caller's transaction

This case may happen with Required, Mandatory, and Supports attributes.

Container's action

Log the exception or error.
Mark the transaction for rollback.
Discard instance.
Throw javax.transaction.TransactionRolledbackException to remote client or throw javax.ejb.TransactionRolledbackLocalException to local client.

Note that while TransactionRolledbackLocalException can nest cause exception, TransactionRolledbackException can't.

Client's view

Receives javax.transaction.TransactionRolledbackException or javax.ejb.TransactionRolledbackLocalException.
Continuing transaction is fruitless.

When bean method runs in the context of a transaction that the container started immediately before dispatching the business method.

This case may happen with Required and RequiresNew attributes.

Container's action

Log the exception or error.
Rollback the container started transaction.
Discard instance.
Throw RemoteException to remote or web service client or throw EJBException to local client.

Note that both RemoteException and EJBException can nest cause exception.

Client’s view

Receives RemoteException or EJBException. If the client executes in a transaction, the client’s transaction may or may not be marked for rollback.

When bean method runs with an unspecified transaction context.

This case may happen with the NotSupported, Never, and Supports attributes.

Container's action

Log the exception or error.
Discard instance.
Throw RemoteException to remote or web service client or throw EJBException to local client.

Client’s view

Receives RemoteException or EJBException.
If the client executes in a transaction, the client’s transaction may or may not be marked for rollback.

System Exception with EJB 3.0

from Chapter 14. Exception Handling of Enterprise JavaBeans Specification Version 3.0

When bean method runs in the context of the caller's transaction

This case may happen with Required, Mandatory, and Supports attributes.

Container's action

Log the exception or error.
Mark the transaction for rollback.
Discard instance.
Throw javax.transaction.TransactionRolledbackException to remote client or throw javax.ejb.EJBTransactionRolledbackException to local client.

Note that EJBTransactionRolledbackException can nest cause exception.

Client's view

Receives javax.ejb.EJBTransactionRolledbackException.
Continuing transaction is fruitless.

When bean method runs in the context of a transaction that the container started immediately before dispatching the business method.

This case may happen with Required and RequiresNew attributes.

Container's action

Log the exception or error.
Rollback the container started transaction.
Discard instance.
Throw EJBException client.

Note that EJBException can nest cause exception.

Client’s view

Receives EJBException. If the client executes in a transaction, the client’s transaction may or may not be marked for rollback.

When bean method runs with an unspecified transaction context.

This case may happen with the NotSupported, Never, and Supports attributes.

Container's action

Log the exception or error.
Discard instance.
Throw EJBException to local client.

Client’s view

Receives EJBException.
If the client executes in a transaction, the client’s transaction may or may not be marked for rollback.

Mapping Requests to Servlets

from SRV.11 of Java Servlet Specification Version 2.4

URL path mapping urles

The container will try to find an exact match of the path of the request to the path of the servlet. A successful match selects the servlet.
The container will recursively try to match the longest path-prefix. This is done by stepping down the path tree a directory at a time, using the ’/’ character as a path separator. The longest match determines the servlet selected.
If the last segment in the URL path contains an extension (e.g. .jsp), the servlet container will try to match a servlet that handles requests for the extension. An extension is defined as the part of the last segment after the last ’.’ character.
If neither of the previous three rules result in a servlet match, the container will attempt to serve content appropriate for the resource requested. If a "default" servlet is defined for the application, it will be used.

Syntax for mapping definition

A string beginning with a ‘/’ character and ending with a ‘/*’ suffix is used for path mapping.
A string beginning with a ‘*.’ prefix is used as an extension mapping.
A string containing only the ’/’ character indicates the "default" servlet of the application. In this case the servlet path is the request URI minus the context path and the path info is null.
All other strings are used for exact matches only.

Example mapping

Path Pattern (`url-pattern`)	Servlet (`servlet-name`)
`/foo/bar/*`	`servlet1`
`/baz/*`	`servlet2`
`/catalog`	`servlet3`
`*.bop`	`servlet4`

Incoming Path	Servlet Handling Request
`/foo/bar/index.html`	`servlet1`
`/foo/bar/index.bop`	`servlet1`
`/baz`	`servlet2`
`/baz/index.html`	`servlet2`
`/catalog`	`servlet3`
`/catalog/index.html`	"default" servlet
`/catalog/racecar.bop`	`servlet4`
`/index.bop`	`servlet4`

Note that in the case of /catalog/index.html and /catalog/racecar.bop, the servlet mapped to “/catalog” is not used because the match is not exact.

Using VisualVM with IBM JDK

2010-12-07T10:01:00.019+09:00

You can use JMX to monitoring IBM JDK with VisualVM.
Java SE 5.0 introduced platform MBeanServer and IBM Java SDK 5.0 or higher naturally provide it. Platform MBeanServer includes various basic managed beans about memory, thread, garbage collection, class loading and so on^[1]. VisualVM can show such information with visual views.

Basically remote access of platform MBeanServer is not activated. You can enable it in several ways.
If you can control the start-up of the VM, you can enable remote access of platform MBeanServer by setting com.sun.management.jmxremote.por system property in command line to launch VM. If you are in position where you can control the system properties, you can programmatically load JMX connector server and expose it using RMI registry.

Method 1. Enabling built-in JMX agent using system properties

You can enable built-in JMX agent of Java runtime with the following system properties explicitly in start-up command of JVM.

-Dcom.sun.management.jmxremote.port=3333
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=false

With VisualVM, you should add new local or remote application using [File > Add JMX Connection] menu item. The connection string has the form of hostname:port such as localhost:3333 or 203.201.71.31:3333.

For more about built-in JMX agent, refer readings 2 below. If more secure setup for remote access to the platform MBeanServer is necessary, it would be really helpful.

Method 2. Exposing platform MBeanServer using JMXConnectorServer programmatically.

When you can not control the start-up command of the JVM, you can expose platform MBeanServer through JMXConnectorServer instance in your code. The JMXConnectorServer should be exposed using RMI registry.

The following code sample shows core steps, acquiring platform MBeanServer, creating JMXConnectorServer instance, creating RMI registry and starting JMXConnectorServer.

   ...

   //acquiring platform MBeanServer
   MBeanServer mbs = ManagementFactory.getPlatformMBeanServer(); 

   //creating JMXConnectorServer instance
   JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://" 
         + InetAddress.getLocalHost().getHostAddress() + ":9999/server");
   JMXConnectorServer cs = JMXConnectorServerFactory.newJMXConnectorServer(url, null, mbs);
  
   //creating RMI registry
   Registry reg = LocateRegistry.createRegistry(9999);
  
   //starting JMXConnectorServer
   cs.start();

   ...

With VisualVM, you should add new local or remote application using [File > Add JMX Connection] menu item. The connection string has the form of service:jmx:rmi:///jndi/rmi://host-address:port/service such as service:jmx:rmi:///jndi/rmi://203.201.71.31:9999/server.
Now you can identify JVM argument or system properties, monitor memory or garbage collection, class loading statistics, thread in timeline, and so on with VisualVM.

If you want stop the remote access to the platform MBeanServer programmatically, just stop the JMXConnectorSever.

   ...

   //stoping JMXConnectorServer
   cs.stop();

   //unload RMI registry
   java.rmi.server.UnicastRemoteObject.unexportObject(reg,true);

   ...

As for me, the above code worked with IBM Java SDK 6.0 on Windows and IBM Java SDK 6.0 64bit on AIX 6.2.

Readings

Data Dictionary

2010-12-01T14:13:00.002+09:00

Data dictionary is data(meta-data) for a database. The structure, relationship and usage of schema objects are maintained at data dictionary.
The implementation and feature of data dictionary is different by database products.

Oracle

Oracle maintains tables and views for data dictionary under SYS user(schema). Plain users can access views according to their roles and privileges.
User accessible views are named with prefix of 'USER_', 'ALL_', or 'DBA_'.

Oracle also maintain data or statistics of database's activity and performance in so-called dynamic performance views. Actually they are views named with prefix of 'V_$' and also owned by SYS schema.
Oracle provides public synonyms named with prefix of 'V$' for users properly privileged.

References

DB2

DB2 UDB provides data dictionary under SYSCAT schema. SYSCAT.TABLES, SYSCAT.VIEWS, SYSCAT.COLUMNS, SYSCAT.INDEXES, SYSCAT.TRIGGERS are views describing the structure of database instance.

For dynamic behavior of database, DB2 UDB provides views under SYSSTAT schema.

References

DB2 System Catalog Views: Everything You Need to Know About Your DB Objects

Characteristics of Oracle

2010-12-01T13:51:00.002+09:00

Quoted identifier is case-sensitive in Oracle

For oracle, identifier such as table name or column name can be quoted with double quotation mark (").
Quoted identifier can be oracle reserved word such as comment, check, add, group, lock or set. But unlike non-quoted identifier, quoted identifier is case sensitive.

Empty string is treated as a `null`

Oracle treats a character value with a length of zero(empty string) as null.
So, the following statement would set null to descn column of produt of which id is 'PD100'.


insert into products (id, name, descn) values ('PD100', 'Vega', '');

Oracle says that this may not continue to be true in future releases, but it seems very difficult to change this feature.

http://download.oracle.com/docs/cd/E11882_01/server.112/e17118/sql_elements005.htm#i59110

JVM Tuning Foundation

2010-11-16T15:38:00.003+09:00

Types of Diagnostic Information in IBM JVM

Javadump (Thread dump)

The Javadump is sometimes referred to as a Javacore or thread dump in some JVMs. This dump is in a human-readable format produced by default when the JVM terminates unexpectedly because of an operating system signal, an OutOfMemoryError exception, or when the user enters a reserved key combination (for example, Ctrl-Break on Windows®). It can also be generated by calling com.ibm.jvm.Dump.JavaDump() from inside the application. A Javadump summarizes the state of the JVM at the instant the signal occurred. Much of the content of the Javadump is specific to the IBM JVM.

Heapdump

The JVM can generate a Heapdump at the request of the user (for example by calling com.ibm.jvm.Dump.HeapDump() from inside the application) or (by default) when the JVM terminates because of an OutOfMemoryError exception. You can specify finer control of the timing of a Heapdump with the -Xdump:heap option. For example, you could request a Heapdump after a certain number of full garbage collections have occurred. The default Heapdump format (phd files) is not human-readable and you process it using available tools such as Heaproots.

System dump (Core dump)

System dumps (also known as core dumps on Linux® platforms) are platform-specific files that contain information about the active processes, threads, and system memory. System dumps are usually large. By default, system dumps are produced by the JVM only when the JVM fails unexpectedly because of a GPF (general protection fault) or a major JVM or system error. You can also request a system dump by calling com.ibm.jvm.Dump.SystemDump() from your application. You can use the -Xdump:system option to produce system dumps when other events occur

Garbage collection data

A JVM started with the -verbose:gc option produces output in XML format that can be used to analyze problems in the Garbage Collector itself or problems in the design of user applications. Numerous other options affect the nature and amount of Garbage Collector diagnostic information produced. See Garbage Collector diagnostics for more information.

Trace data

The IBM JVM tracing allows execution points in the Java code and the internal JVM code to be logged. The -Xtrace option allows the number and areas of trace points to be controlled, as well as the size and nature of the trace buffers maintained. The internal trace buffers at a time of failure are also available in a system dump and tools are available to extract them from a system dump. Generally, trace data is written to a file in an encoded format and then a trace formatter converts the data into a readable format. However, if small amounts of trace are to be produced and performance is not an issue, trace can be routed to STDERR and will be pre-formatted.

The above are cited from the diagnostic guide of IBM Java SDK which you can find from here.

Useful DOS Commands

2010-11-09T20:27:00.003+09:00

pathping

On a windows, you can use pathping command to view the route to the specified IP address.


c:\>patfhping www.google.com

For more about pathping, refer the followings.

Tips on JDBC

2010-10-19T14:20:00.014+09:00

JDBC Drivers by DBMS Product

The followings are starting pages for JDBC drivers for each DBMS product.

Oracle Database : http://www.oracle.com/technetwork/database/features/jdbc/index-091264.html
IBM DB2 : http://www-01.ibm.com/support/docview.wss?rs=71&uid=swg21363866
Microsoft SQL Server : http://msdn.microsoft.com/en-us/sqlserver/aa937724

Connection Properties of JDBC Driver

Oracle Database

Available connection properties of Oracle database's JDBC driver is described in API documentation of JDBC driver.
In case of Oracle database 11g, you can found them in the following page.

OracleDataSource.setConnectionProperties(java.util.Properties value)

IBM DB2

Available properties on JDBC driver for DB2 version 9.7 are described in the following page.

Properties for the IBM Data Server Driver for JDBC and SQLJ

Microsoft SQL Server

Setting the Connection Properties - SQL Server 2008 R2

Diagnosability in JDBC

Oracle Database

http://www.comp.dit.ie/btierney/oracle11gdoc/java.111/b31224/diagnose.htm

Oracle JDBC Driver

Compatibility of JDBC Driver

Tips on DB2

2010-09-15T14:08:00.012+09:00

Official Documents

Setup Related

Connectivity Related

Programming Related

Session and Context Related

Tuning Related

Tips on XML

2010-07-19T00:58:00.034+09:00

Common XLM Schemas

SAX2 Features and Properties

Making JAXP recognize RELAX-NG schema

Although JDK 1.5 and 1.6 are aware of RELAX-NG considering XMLConstants.RELAXNG_NS_URI, JDK 1.5 and JDK 1.6 don't include RELAX-NG implementation. So, if you use RELAX-NG as a schema for the validation API of JAXP, you should include RELAX-NG implementation to use in your classpath and set system variable to use it before the validation code.


   ...
   System.setProperty("javax.xml.validation.SchemaFactory:" + XMLConstants.RELAXNG_NS_URI, 
         "com.thaiopensource.relaxng.jaxp.CompactSyntaxSchemaFactory");

   SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.RELAXNG_NS_URI);
   ...

The most well-known RELAX-NG implementation in Java seems to be jing.

Define empty element using XML Schema

Declaring Empty Elements

Built-in Datatypes of XML Schema

A value of '100.0' is invalid with xsd:integer or it's subtypes because xsd:integer is defined with it's fractionDigits is 0.

Meaning of Fundamental Element of XML Schema

simpleType, complexType, simpleContent, complexContent, ... all these are very confusing. So, you need to understand the exact meaning or usage of each element and tell the differences between them.

`simple types`

Elements that contain numbers (and strings, and dates, etc.) but do not contain any subelements are said to have simple types.

`complex types`

Elements that contain subelements or carry attributes are said to have complex types.

`simpleContent`

The simpleContent element can specify attributes for simple types.
The simpleContent element can specify attribute types via extension or restrict existing attribute types via restriction to simple types or to complex types with simple content.

`complexContent`

The complextContent element can specify nested element types. This includes the special case of zero element, also known as 'empty content'. The comlextContent also provides functionality that permits text interspered with elements, also known as 'mixed content'.

Thread-safeness of Factories in JAXP

Factory classes in JAXP such as SAXParserFactory, DocumentBuilderFactory, SchemaFactory are not thread-safe.

DocumentBuilder

DOM related core classes in JAXP, in other words DocumentBuilderFactory, DocumentBuilder, and Document are not thread-safe. Mutator methods such as DocumentBuilderFactory.setSchema(), DocumentBuilderFactory.setFeature(), DocumentBuilderFactory.setIgnoringComments(), DocumentBuilderFactory.setNamespaceAware(), DocumentBuilderFactory.setValidating(), DocumentBuilder.setEntityResolver(), and DocumentBuilder.setErrorHandler() means those classes are not thread-safe.

DocumentBuilderFactory or DocumentBuilder object may be relatively resource demanding. So, they should not be instantiated every time you build a document. But they are not thread-safe, so they should be confined properly.
In usual case where your application need parsing method for your specific documents, you would better provide public parser method that create document object and reuse document builder factory and document builder internally.


public class ApplicationDocumentParsers{

   protected DocumentBuilder orderDocBuilder;
   protected DocumentBuilder paymentDocBuilder;
   protected DocumentBuilder deliveryDocBuilder;

   public ApplicationDocumentParsers(){

      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
      dbf.setNamespaceAware(true);
      dbf.setValidating(false);
      dbf.setXIncludeAware(false);

      //initiate document builders
      dbf.setSchema("order.xsd");
      this.orderDocBuilder = dbf.newDocumentBuilder();

      dbf.setSchema("payment.xsd");
      this.paymentDocBuilder = dbf.newDocumentBuilder();

      dbf.setSchema("delivery.xsd");
      this.deliveryDocBuilder = dbf.newDocumentBuilder();

   }

   public Document parseOrderDoc(InputStream is){
      return this.orderDocBuilder.parse(is);
   }

   public Document parsePaymentDoc(InputStream is){
      return this.paymentDocBuilder.parse(is);
   }

   public Document parseDeliveryDoc(InputStream is){
      return this.deliveryDocBuilder.parse(is);
   }

I think there maybe threa-safe or immutable document builder or document builder factory but, I haven't still found well-known one.

javax.xml.validation

SchemaFactory class is not thread-safe, but Schema class is immutable and thread-safe.

Meaning and Pronunciation of Xerces

As for me who is not native with English, the word starting with 'x' is very unfamiliar and can't even imagine how to pronounce such words. Although I have used Apache Xerces for more than 5 years, I recently become to know the exact pronunciation of 'Xerces'. This may be silly to those who use English as their mother tongue, most of application developers around me are same with me. Anyway you can hear the pronunciation and read the meaning of 'Xerces' at the following pages.

Resources on JAXB

There aren't so much books, tutorials or articles about JAXB as JAXP. Specially, it's much difficult to find in-depth materials on JAXB 2.0.
The followings are the one I have found to be useful.

Embedding Schematron to XML Schema

Schematron can defines complex rules such as relations between values of elements which can't be expressed with XML Schema. But defining the whole schema of an XML document using Schematron is too expensive and improper. So, defining basic structure and rules using XML Schema and more complex rules using Schematron seems to be good strategy.

Then, maintaining a pair of schema files for a XML document is somewhat bothering. Is it possible to merge two schema files into one ?

The following article explains how to embedding constraints expressed with Schematron syntax into the XML Schema file. The basic idea is using element.

Extending XML Schemas

Resources on XML Catalog

Document type declaration, public identifier, system identifier

Syntax

document-type-declaration = (external-subset, internal-subset)|external-subset|internal-subset

document-type-delaration = '<!DOCTYPE' root-element-name external-subset? ('[' internal-subset ']')? '>'

external-subset = ('PUBLIC' public-identifier system-identifier)|('SYSTEM' system-identifier')

public-identifier : identifier which is meant to be universally unique within its application scope.
system-identifier : is typically a fragmentless URI reference which is intended to identify a document type which is used exclusively in one application.

Sample

XHTML 1.0

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
                         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

Web application deployment descriptor for Servlet 2.3

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" 
                            "http://java.sun.com/dtd/web-app_2_3.dtd">

IoC configuration of Spring framework 2.0

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN"
            "http://www.springframework.org/dtd/spring-beans-2.0.dtd">

SQL map of iBATIS 2.0

<!DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
                        "http://ibatis.apache.org/dtd/sql-map-2.dtd">

DocBook 5.0

<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V5.0/EN"
               "http://www.oasis-open.org/docbook/xml/5.0/docbook.dtd" [
<!ENTITY chap1 SYSTEM "chap1.xml">
<!ENTITY chap2 SYSTEM "chap2.xml">
]>

XML Schema Documentation Tools

xsddoc
The xsddoc subproject is a XML Schema documentation generator for W3C XML Schemas.
xs3p
The XS3P schema documentation generator is simply an XSLT stylesheet, which generates HTML documentation from an XSD schema file.

Small Tips

Type extension using <xs:extension> element can't override the type of the element in base type.
- How to override a Xml Schema element ?
- XML Schema extension Element

Tips on Eclipse

2010-07-09T00:12:00.008+09:00

Configuration

Eclipse runtime options

If you want to know what can you do with eclipse.ini file, refer the followings.

Runtime options for Eclipse 3.5

Task Tags for Java Souce and XML File on Eclipse 3.3

For eclipse 3.3 "Task Tags" for java source file are enabled by default with 3 basic tags (TODO, FIXME, XXX) but task tags for XML file are not enabled. To enable task tags for XML file, change the settings on [Windows > Preference > Web and XML > Task Tags] menu.

Optimization

Optimizing `eclipse.ini`

You can find interesting wrtings on eclipse.ini to increase the performance of Eclipse at the following page.

http://stackoverflow.com/questions/142357/what-are-the-best-eclipse-34-jvm-settings#144349

Troubleshooting

Eclipse doesn't start-up.

"The workspace exited with unsaved changes in the previous session; refreshing workspace to recover changes." at .metadata/.log

Tips on JBoss

2010-05-28T10:15:00.017+09:00

Fundamental

Startup parameter http://community.jboss.org/wiki/JBossRunParameters
Enabling remote access to JBoss 4.2 : http://jlorenzen.blogspot.com/2007/10/enabling-remote-access-to-jboss-42.html
Class loading configuration : http://community.jboss.org/wiki/ClassLoadingConfiguration
Explains how-to setup class loading isolation of J2EE modules using <loader-repository> element in jboss-app.xml, jboss.xml or jboss-web file.
Configuring the Deployment Scanner in conf/jboss-service.xml : https://community.jboss.org/wiki/ConfiguringTheDeploymentScannerInConfjbossSystemxml

Data Access

Config data-source : http://community.jboss.org/wiki/configdatasources
Config data-source and monitor connection pools : http://www.mastertheboss.com/en/jboss-server/96-jboss-datasource-configuration.html

Performance

Readings on tuning JBoss are listed here.

Security

Encrypt passwords of data-sources : http://community.jboss.org/wiki/encryptingdatasourcepasswords
Config JCA login module : http://community.jboss.org/wiki/ConfigJCALoginModule

Networking

Identify and configure TCP/UDP port used : http://community.jboss.org/wiki/UsingJBossBehindAFirewall

EJB Programming

Naming Rules of Schema Objects by Database

2010-05-25T19:09:00.006+09:00

The max. length of identifiers

	Database	Table	View	Sequence	Synonym	Index	Constraint	Trigger	Procedure/Function	Database Link	Column	Alias
Oracle	8	30	30	30	30	30	30	30	30	128	-	-
MySQL 5.0	64	64	64	-	64	64	-	64	64	-	64	255
PostgreSQL 8.x	63	63	63	63	-	63	63	63	63	-	63	63

Symbols

2010-04-19T01:59:00.022+09:00

Punctuation

Name	Symbol	HTML 4.0 Entity	Remarks
parentheses	( )		round brackets, curved brackets, oval brackets
square brakets	[ ]		brakets
braces	{ }		curly brackets, flower brackets
guillemets	« »	« »
single quotation mark	‘ &rsquo	‘ &rsquo
double quotation mark	“ &rdquo	“ &rdquo
period	.		full stop, dot, point
ellipses	…	…
question mark	?
exclamation mark	!
comma	,
colon	:
semicolon	;
dash	– &mdash	– &mdash
hyphen	‐
apostrophe	'
slash	/		stroke

Typography

Name	Symbol	HTML 4.0 Entity	Remarks
tilde	~	&tilde;
grave accent	`
at sign	@
number sign	#		pound sign, hash mark
percent	%
caret	^
circumflex	ˆ	&circ;	hat
ampersand	&	&
asterisk	*	&lowast;	star
underscore	_		understroke
backslash	\
vertical bar	\|		pipe, stick, vertical slash, thick colon
pilcrow	¶	¶	paragraph mark, paragraph sign
bullet	•	•
section sign	§	§
prime	′	′	minutes, feet
double prime	″	″	seconds, inches
therefore sign	∴	&there4;

Readings

1st on AspectJ

2010-04-08T09:55:00.003+09:00

Semantics and Syntax Reference

Automatic Number of Headers in HTML

2010-03-11T02:08:00.024+09:00

You can generate the number of headers(h1 ... h6) in HTML using couner-reset, counter-increment, content properties and :before pseudo element of CSS2.
But this feature is not supported with Internet Explorer 6 and 7.

To localize the numbering, you can demarcate the area using division which has id provperty.
The following sample shows how you can do it very intuitively.

<style type="text/css">
#go-out-with-her { counter-reset:step; }
#go-out-with-her h5:before{
   content:counter(step) ". ";
   counter-increment:step;
}
</style>

<div id="go-out-with-her">
<h5>Choose a movie</h5>
<p>The movie maybe one of the most common ...</p>

<h5>Choose time</h5>
<p>
... Friday or Saturday would be the most proper day.  
Avoid Sunday or too hot day. A slightly rainy day could be positive...
</p>

<h5>Choose a theater</h5>
<p>
... You should think in advance where to go after the movie. 
A nice restaurant or a park ...
</p>

<h5>Call her</h5>
<p>
... Avoid Monday.... Three or four days before would be nice...
</p>

<h5>Prepare a small gift</h5>
<p>
The present should not too expensive, big or uncommon. 
Well-known book, CD could be nice.
</p>
</div>

The above source would be look like the following in the browser.

Choose a movie

The movie maybe one of the most common ...

Choose time

... Friday or Saturday would be the most proper day. Avoid Sunday or too hot day. A slightly rainy day could be positive...

Choose a theater

... You should think in advance where to go after the movie. A nice restaurant or a park ...

Call her

... Avoid Monday.... Three or four days before would be nice...

Prepare a small gift

The present should not too expensive, big or uncommon. Well-known book, CD could be nice.

The following CSS rules can be applied more generally.

div.post-body { 
  counter-reset:step-for-h4
}
div.post-body h4:before{
  content:counter(step-for-h4) ". ";
  counter-increment:step-for-h4;
}
div.post-body h4 { 
  counter-reset:step-for-h5 
}
div.post-body h5:before{
  content:counter(step-for-h4) ". " counter(step-for-h5) ". ";
  counter-increment:step-for-h5;
}
div.post-body h5 { 
  counter-reset:step-for-h6 
}
div.post-body h6:before{
  content:counter(step-for-h4) ". " counter(step-for-h5) ". " counter(step-for-h6) ". ";
  counter-increment:step-for-h6;
}

For more readings.

Tips on Redmine

2010-02-25T14:35:00.014+09:00

The number in the parenthesis means the version of Redmine.

Features and Shortness

Features

The pages are based on 'XHTML 1.0 Transitional' (0.9.2)

Shortness

List syntax in wiki, especially with ordered list and nested list, can't provide to use blank lines between list items. (0.9.2)
For example, the following is not to be made simply with Wiki

1. Spring Framework
  - Dependency injection.
  - Application module or component model.

2. iBATIS
  - Data assess.
  - Separation of source and SQL statement.
  - Effective and easy syntax for dynamic query.
  - No resource leakage due to unclosed ResultSet or Statement object.

Each project can't define its own set of issue status. All the project in the Redmine have to share the same set of issue status. (0.8.4)
Writing directly HTML tags in Wiki or Forum is not allowed. (0.9.2)
~~Tracker and name of the issue can't be changed. Why? (0.9.2)~~
I was wrong. Changing tracker and name of an issue has been possible since 0.9.x
An issue can't be assigned to more than two members. (0.9.2)

Notable Redmine Plugins

Redmine DMSF : http://code.google.com/p/redmine-dmsf/
is slowly emerging Document Management System Features plugin for Redmine issue tracking system and is aimed to replace current Redmine's Documents module.
Wiki Extensions : http://www.r-labs.org/projects/r-labs/wiki/Wiki_Extensions_en
adds usefull wiki macros into your Redmine.

Installing Redmine on Windows

2010-02-12T14:18:00.021+09:00

Installation Procedure

Redmine, which is one of the most promising collaboration software including wiki, issue tracking, forum and etc., is based on Ruby. When you install it, you need some packages for ruby and use commands in ruby's world. So, for those who have no experience on Ruby, the installation guide at Redmine's homepage is not enough.

To install Redmine on windows, you should work the following steps. I intalled Redmine 0.9.2 with them. Redmine, as of 0.9.2, supports MySQL 4.1+, PostgreSQL 8 and SQLite 3. MySQL is supposed in the followings. You can easily apply the steps for database for PostgreSQL and SQLite.

Install Ruby using Ruby installer.
Adjust RubyGems.
Install Rake.
Install Rails.
Install internationalization package.
Install MySQL API module for Ruby.
Download and extract Redmine binaries.
Create user and database for Redmine in MySQL.
Setup database configuration of Redmine.
Generate a session store secret.
Update PATH variable of Windows.
Build database schema.
Build default configuration data into the database.
Test the installation.

Install Ruby using Ruby installer.

You can find Ruby Installer for Windows in the following location. : http://rubyinstaller.org/
Ruby Installer is .exe file which make it easy to installing Ruby on windows. It includes RubyGems which is packaging tool for Ruby based applications.
From 0.8.x to 1.1.x of Redmine, Ruby 1.8.6 or 1.8.7 is necessary and 1.9.x is not supported.
After you install Ruby using Ruby Installer, you can find ruby.exe and gem.bat in the bin directory under the Ruby's home.
Ruby Installer will add the bin directory (eg. c:\ruby\bin) to PATH variable of your windows.

You need to install several packages before installing redmine. Those includes rake, rails, and rack. According to the version of the Redmine for you to install, each package has limitation for its version. For this, refer to the official installation guide of Redmine.

During installation, you can identify the packages installed in your machine using the following command.


c:\ruby\bin>gem list -l

It seems to be no problem to install different versions of the same package at the same machine. Applications or packages of ruby seem to be able to find proper version among more than one versions of the necessary package in the machine.

Adjust RubyGems.

You should use RubyGems 1.4.2 or less to install Redmine 1.1.2 correctly. Using RubyGems 1.5.2 with Redmine 1.1.2 would fail when building database schema.

The RubyGems would be installed with Ruby. The version of RubyGems can be identified like this.

c:\ruby\bin>gem -v

If the installed version of the RubyGems is higher than the one required by Redmine, you can downgrade the RubyGems using commands like following.

c:\ruby\bin>gem -v
1.5.2
c:\ruby\bin>gem install rubygems-update -r -v=1.4.2
...
c:\ruby\bin>update_rubygems
...
c:\ruby\bin>gem -v
1.4.2

Install Rake.

Rake is build tool for Ruby. It's like make for Unix or Ant for Java.
You can install Rake using RubyGems's remote installation without manually downloading binaries to your local computer.

c:\ruby\bin>gem install rake -r

Actually, you can run gem.bat in any directory, 'cause Ruby Installer will add the bin directory to the PATH variable.
In the above sample command, -r option means remote installation where the RubyGems would download the wanted packages from the remote site.

Install Rails.

Rails is that famous application framework for Ruby. It is also called Ruby on Rails or RoR.

Redmine 1.1.x requires Rails 2.3.5, so, you have to specify the version of the Rails to install with -v option.

c:\ruby\bin>gem install rails -r -v=2.3.5

Note that the RubyGems also install Rack 1.0.1 during installing Rails 2.3.5. Rack is a web server interface of the ruby for ruby frameworks.

Install internationalization package.

Redmine 1.1.2 with MySQL 5.0 needs 0.4.2 not higher version of i18n package.


c:\ruby\bin>gem install i18n -r -v=0.4.2

Install MySQL API module for Ruby.

First make query for available mysql package. The following command will show the latest version of mysql.

c:\ruby\bin>gem list mysql -r

There may be different mysql packages not only by version but also by platform. If so, you should specify the platform using --platform option.

c:\ruby\bin>gem install mysql -r -v 2.8.1 --platform x86-mswin32

Download and extract Redmine binaries.

You can get Redmine in zip format from here.
You can just extract it any directory you like such as c:\appls\redmine.

Create user and database for Redmine in MySQL.

If you don't have MySQL already, install and setup MySQL 5.0.
You should create a database for Redmine, create a user and then grant proper privilege to the user. You can use the following SQL statements after logging-in as an administrator

create database redmine character set utf8;
create user 'redmine'@'localhost' identified by 'passwordforredmine';
grant all privileges on redmine.* to 'redmine'@'localhost';

Setup database configuration of Redmine.

For this, refer official installation guide of Redmine

Generate a session store secret.

If you don't have session_store.rb in config\initializers\ directory under Redmine home directory (eg. c:\appls\redmine\), you should generate it first. You should run Rake at Redmine home directory.


c:\appls\redmine>rake generate_session_store


And now, you can generate secret.

C:\appls\redmine>rake config/initializers/session_store.rb RAILS_ENV=production



Update PATH variable of Windows.


Ruby's mysql pacakge needs libmysql.dll at runtime. Previously the dll was included in Ruby installer but at some time, it became excluded.

Originally, libmysql.dll is located in the bin directory of MySQL installation.

So, you need to update PATH variable of your Windows to include MySQL's bin directory.



Build database schema.

You should run your MySQL first. And then, use the following Rake command at Redmine home directory.

C:\appls\redmine>rake db:migrate RAILS_ENV=production


Build default configuration data into the database.

While still your MySQL is running,

C:\appls\redmine>rake redmine:load_default_data RAILS_ENV=production


Test the installation.

While still MySQL is running, start your Redmine.

C:\appls\redmine>ruby script/server webrick -e production


Access the login page : http://localhost:3000/login

Try to login built-in default account : admin:admin



References

  Official installation guide for Redmine : http://www.redmine.org/wiki/redmine/RedmineInstall
  A concise blog article to install Redmine on Windows : http://www.codeweblog.com/at-windows-on-the-installation-of-redmine/

  Ruby Installer homepage : http://rubyinstaller.org/
  RubyGems manual : http://docs.rubygems.org/
  Rack : http://rack.rubyforge.org/



Prefixes for Place-value Notations
2010-02-08T11:13:00.019+09:00


  Case
  Base
  Prefix
  Format
  Example


  HTML/XML Character Entities
  decimal
  &#
  &#nnnn
  
  &#169 for copyright symbol.

  &#913 for Greek capital letter alpha. 
  


  HTML/XML Character Entities
  hexadecimal
  &#x
  &#xhhhh
  
  &#xA9 for copyright symbol.

  &#x391 for Greek capital letter alpha. 
  


  CSS Colors
  hexadecimal
  #
  #hhhhhh or #hhh
  
  #000000 for black, #ffffff for white,

  #800080 for purple, #808000 for olive,

  #ffa400 for orange
  


  Unicode Code Points
  hexadecimal
  U+
  U+hhhh, U+hhhhh or U+hhhhhh
   
  


  Unicode Escape Sequence for Character and String Literals
  hexadecimal
  \u
  \uhhhh
  
  \u0008 for backspace BS,

  \u0022 for double quote "

  \u005c for backslash \ 
  


  Octal Escape Sequence for Character and String Literals
  octal
  \
  \ooo
  
  \10 for backspace BS,

  \42 for double quote "

  \134 for backslash \ 
  




Tips on vi
2009-12-23T17:08:00.013+09:00
Readings


  vi Reference
  Vim documentation
  Vim Quick Reference Card
  Vim options list



  Changing character-set of the file currently open in the editor (Korean)


Show options

To show all options and their current values, use the following command.

:set all

To confirm the specific optiona, use the following command.

:set option-name?




View files in hex format

Command to change to hex view.
:%!xxd

Command to change to normal(ascii) view.
:%!xxd -r


On some platforms where xxd is not available, you may try to use od (octal dumping program) command like this.

:%!od -A d -x


For more about od, refer the following

   http://www.opengroup.org/onlinepubs/9699919799/utilities/od.html



Confirm and change current encoding in vi editor

With vi open, you can confirm the encoding used to display the current text of file with the following command.

:set encoding?


If the current coding is not proper with the file to read, you can change the encoding using set encoding command like the following.

:set encoding utf-8

The above sample is when changing to utf-8.

To list available encodings, you can use the following command.

:help encoding-names




Show line numbers

To show line numbers with vi editor, you can use the following command.

:set number

To hide line numbers, use the following command.

:set nonumber




Tips on Windows
2009-11-18T17:46:00.013+09:00
Readings : References, Tutorials, Articles


  Windows XP Professional : Command-line reference



  The Disk is write-protected. Remove the write-protection
  How to Disable Write Access to USB Hard Disk and Flash Key Drives
  Change the Favorites Folder Location
  IE7 in Vista: Folder Redirection for Favorites on the Same Machine
  How to change FileZilla settings save path
  Editing configuration of Mozilla applications



Mozilla applications


  Managing bookmarks of Firefox
  Firefox : Export bookmarks to bookmarks.html each time the browser shuts down
  Calendar : How do I save my calendar file on a local/network drive
  Thunderbird and Exchange / OWA
  mozillaZine : Outlook Web Access




Excel


  Excel Function Reference (in Korean)
  Excel Date & Time Calculations
  Generate Gantt like chart in Excel (Korean)




Creating or modifying windows service

To create, delete, start or stop a window service, you can use sc command (sc.exe).

The following articles describe the command in detail.


http://support.microsoft.com/kb/251192
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/sc.mspx?mfr=true


A typical example to register new service is like this.

c:\> sc create svn
        binpath= "C:\svn\bin\svnserve.exe --service -r C:\repos"
        displayname= "Subversion Server"
        depend= Tcpip
        start= auto


Note that the equal sign(=) between option name and option value should follow right after option name without any space and should have at least one space before option value.  So, if you write depend=Tcpip with the above example, it wouldn't work.


Delete cached password for network drive

At DOS console, run the program like the following.
C:\>control userpasswords2



Find the PID of the process occupying specified TCP/UDP port

At DOS console, run the netstat and filter the result using findstr command.

The example is :

C:\>netstat -nao | findstr 1098


Useful Command-line Tools

pathping

On a windows, you can use pathping command to view the route to the specified IP address.

c:\>patfhping www.google.com
 

For more about pathping, refer the followings.

   http://www.computerhope.com/pathping.htm
   http://en.wikipedia.org/wiki/PathPing



tasklist

Windows equivalent for ps.

For example, you can find the program or process using PID of 1544, using tasklist like the following.



For complete description of tasklist, refer http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/ntcmds_o.mspx?mfr=true


Tips on Oracle for Non-admin User
2009-11-17T10:02:00.030+09:00
Readings : References, Tutorials, and Articles


  Oracle Database 10g Documentation Library
  System Privileges of Oracle Database 10g
 



Finding roles and privileges of a user or current session.

With more emphasis on securities, default privileges for a regular(non-DBA) user is very restrictive.  As of Oracle database 10.2, CONNECT and RESOURCE which are typical predefined roles for a regular user don't include create view and create synonym privileges.


So often, you should have to check what roles and privileges are given for a user. You can do that using the following statements.

-- finding all roles for the current session
SELECT * FROM SESSION_ROLES;

-- finding all privileges for the current session
SELECT * FROM SESSION_PRIVS;



Required roles to access dynamic performance (V$) views.

To access the dynamic performance views such as V$SESSION, V$PARAMETER and V$LOCK as well as static dictionary views of DBA such as DBA_TABLES, DBA_SEQUENCES and DBA_SYNONYMS, the user need SELECT_CATALOG_ROLE

DBA user can grant the role to the user using the following statement.


GRANT select_catalog_role TO :username;



Finding the values of parameters currently in effect.

Checking the context of current operation is really one of the most basic thing you can do in any circumstances.
With Oracle, that is parameters. You can identify the current value of SGA max size, max sessions, optimizer mode or other settings throughout the parameter.

SELECT * FROM V$PARAMETER ORDER BY name;


V$PARAMETER is one of public synonyms in default installation.


Identifying the character-set of the Oracle instance

Use the following statement.

select * from nls_database_parameters
where parameter = 'NLS_CHARACTERSET';



Changing the password of the user

Use the following statement.


ALTER USER :username IDENTIFIED BY :password;


Be cautious not to mark single quotation mark around values of :username and :password. The following is simple example.


ALTER USER hr IDENTIFIED BY hr88rh;



When you are connected to Oracle using SQL*Plus, you can use password command to change your password.


The following is sample command line when changing password of hr user

SQL>password
Changing password for hr
Old password :
New password : 
Retype new password :
Password changed




Viewing information about users

About current user, access the following dictionary views.



   View
   Description


   USER_USERS
   Describes only the current user.


   ALL_USERS
   Lists users visible to the current user, but does not describe them.


   USER_TS_QUOTAS
   Describes tablespace quotas for current user.


   USER_RESOURCE_LIMITS
   Displays the resource limits for the current user.


   USER_PASSWORD_LIMITS
   Describes the password profile parameters that are assigned to the user.




More privileged users can use the following views to access the information of all users.




   View
   Description


   DBA_USERS
   Describes all users of the database.


   DBA_TS_QUOTAS
   Describes tablespace quotas for users.


   DBA_PROFILES
   Displays all profiles and their limits.


   V$SESSION
   Lists session information for each current session, includes user name.




Use connect command of SQL*Plus without tnsnames.ora



  How to connect SQLPlus without tnsnames.ora
  



Identifying execution plan of query

Using DBMS_XPLAN.DISPLAY_CURSOR function

The execution plan of last executed query in plan table can be printed out using DBMS_XPLAN.DISPLAY_CURSOR function.


DBMS_XPLAN package was introduced at Oracle 9i, but DISPLAY_CURSOR function was added with Oracle 10g.

DBMS_XPLAN.DISPLAY_CURSOR function accesses V$SESSION, so the user need to have SELECT_CATALOG_ROLE role to correctly execute select * from table(DBMS_XPLAN.DISPLAY_CURSOR)

select employee_id, first_name || ' ' || last_name as name, department_id, job_id, manager_id  
from hr.employees  
where job_id = 'SA_REP'  
and manager_id in (146, 147);  

select * from table(DBMS_XPLAN.DISPLAY_CURSOR);


If you want to see just execution plan and not to actually execute the query.  You can use EXPLAIN PLAN statement.

explain plan for
select employee_id, first_name || ' ' || last_name as name, department_id, job_id, manager_id  
from hr.employees  
where job_id = 'SA_REP'  
and manager_id in (146, 147);  

select * from table(DBMS_XPLAN.DISPLAY_CURSOR);



Using autotrace with SQL*Plus

When using SQL*Plus, you can turn on autotrace feature for the current session using SET AUTOTRACE ON command.


After the autotrace is enabled, execution of query would display normal result data and the execution plan right after it. 

To use this feature, you must create a PLAN_TABLE table in your schema and then have the PLUSTRACE role granted to you.

SQL>SET AUTOTRACE ON
SQL>SELECT employee_id, first_name || ' ' || last_name as name, department_id, job_id, manager_id
2 FROM hr.employees
3 WHERE job_id = 'SA_REP'  
4 AND manager_id IN (146, 147);  


If you want to see just execution plan and not to actually execute the query, you can use SET AUTOTRACE TRACEONLY command.

SQL>SET AUTOTRACE TRACEONLY
SQL>SELECT employee_id, first_name || ' ' || last_name as name, department_id, job_id, manager_id
2 FROM hr.employees
3 WHERE job_id = 'SA_REP'  
4 AND manager_id IN (146, 147);  



Readings


  DBMS_XPLAN of Oracle Database 10.2
  Tracing Statements of Oracle Database 10.2
  EXPLAIN PLAN statement of Oracle Database 10.2





Loading P6Spy Configuration File at Custom Position
2009-10-20T20:01:00.009+09:00

P6Spy automatically loads configuration file named spy.properties on one of the top directories in classpath at initialization. For example, if your classpath is '/foo:/foo/bar.jar', /foo/spy.properties would be automatically configured.


But if you should use different name or position, for example /foo/spy-test.properties or /foo/baz/qux/spy.properties, you can use spy.properties system property to set the position and name of property file relative to classpath.

For example, if you want to load /foo/baz/qux/spy-sql.properties file with classpath of '/foo:/foo/bar.jar'., you can use command-line like the following. Note that the value should be relative to classpath. It is not /foo/baz/qux/spy-sql.properties but baz/qux/spy-sql.properties. 

java -Dspy.properties=baz/qux/spy-sql.properties MyApplication.java




You can also specify the property file with custom position and name using p6.home system property. Refer the 'Command Line Options' section of the official document(http://www.p6spy.com/documentation/other.htm#common). But in this case, you should specify the absolute path of the property file, which is less portable.

In case of JUnit 4.x test case, you can set the system property in BeforeClass method which would be executed before loading P6Spy.

public class MyTest{
   @BeforeClass
   public static void setUpBeforeClass() throws Exception{
      System.setProperty("spy.properties", "baz/qux/spy-sql.properties");
   }

   @Test
   public void testMyMethod(){
      //...
   }

   //...
}


There are few interesting article about integrating Spring framework and P6Spy.


  http://templth.blogspot.com/2004/11/integrate-p6spy-with-spring.html
  http://atog.be/2005/07/12/p6spy-and-spring.html


The configuration of P6Spy could be more flexible using above tip. When I have finished the testing, I will write it also.



Ant Task to Process XSLT Including XInclude
2009-10-20T14:07:00.011+09:00

Ant's built-in task xslt seems to have problem to transform XML documents which use XInclude.  With simple documents and xslt based script, I couldn't correct result with the following warning message saying that it couldn't process XInclude.


[xslt] Element include in namespace 'http://www.w3.org/2001/XInclude' encountered in book, 
but no template matches.



I had searched Google to find the same cases and solutions for a few hours, but I couldn't found the helpful one.



But, using java task of Ant, I can write working script for documents using XInclude.

The following is my script.


 <artifact:dependencies pathId="dependency.classpath" filesetId="dependency.fileset">
  <dependency groupId="xerces" artifactId="xercesImpl" version="2.9.1" />
  <dependency groupId="xalan" artifactId="xalan" version="2.7.1" />
  <dependency groupId="saxon" artifactId="saxon" version="6.5.3" />
  <dependency groupId="net.sf.docbook" artifactId="docbook-xml" 
    version="5.0-all" classifier="resources" type="zip" />
  <dependency groupId="net.sf.docbook" artifactId="docbook-xsl" 
    version="1.74.3" classifier="resources" type="zip" />
  <dependency groupId="net.sf.docbook" artifactId="docbook-xsl" 
    version="1.74.3" classifier="ns-resources" type="zip" />
  <dependency groupId="net.sf.docbook" artifactId="docbook-xsl-xalan" version="1.0.0" />
  <dependency groupId="net.sf.docbook" artifactId="docbook-xsl-saxon" version="1.0.0" />
  <dependency groupId="org.apache.xmlgraphics" artifactId="fop" version="0.93"/>
 </artifact:dependencies>

 <target name="build-spec-xhtml-using-java-saxson-6">
  <delete file="${target.base}/spec/xhtml/spec.html"/>
  <java classname="com.icl.saxon.StyleSheet" fork="yes" 
        dir="." failonerror="true">
   <classpath refid="dependency.classpath" />
   <sysproperty key="javax.xml.parsers.DocumentBuilderFactory"
    value="org.apache.xerces.jaxp.DocumentBuilderFactoryImpl"/>
   <sysproperty key="javax.xml.parsers.SAXParserFactory"
    value="org.apache.xerces.jaxp.SAXParserFactoryImpl"/>
   <sysproperty key="org.apache.xerces.xni.parser.XMLParserConfiguration"
    value="org.apache.xerces.parsers.XIncludeParserConfiguration"/>
    
   <arg line="-o ${target.base}/spec/xhtml/spec.html"/>
   <arg line="-l"/>
   <arg line="./spec/spec.docbook"/>
   <arg line="${docbook.xsl.dir}/xhtml/docbook.xsl"/>

   <!-- parameters for XSLT -->
   <arg line="toc.max.depth=3"/>
   <arg line='generate.toc="book toc,title,figure,table,example,equation"'/>
   <arg line="use.extensions=1"/>
   <arg line="part.autolabel=1"/>
   <arg line="chapter.autolabel=1"/>
   <arg line="section.autolabel=1"/>
   <arg line="section.label.includes.component.label=1"/>
   <arg line="section.autolabel.max.depth=4"/>
   <arg line="appendix.autolabel=A"/>
   <arg line="chunker.output.indent=yes"/>
   <arg line="chunker.output.encoding=UTF-8"/>
   <arg line="html.stylesheet=docbook-freebsd.css"/>
   <arg line="generate.id.attributes=1"/>
   <arg line="para.propagates.style=1"/>
   <arg line="entry.propagates.style=1"/>
   <arg line="emphasis.propagates.style=1"/>
   <arg line="phrase.propagates.style=1"/>
  </java>
 </target>



For more information, refer the followings.


  http://www.sagehill.net/docbookxsl/Xinclude.html#XercesXinclude
  http://www.sagehill.net/docbookxsl/Parameters.html#ParameterSyntax
  http://www.sagehill.net/docbookxsl/Xinclude.html#XercesXinclude
  http://saxon.sourceforge.net/saxon6.5.2/using-xsl.html
  http://ant.apache.org/manual/CoreTasks/java.html



Java System Properties for JAXP (Java API for XML Parsing)
2009-10-19T21:09:00.013+09:00
javax.xml.parsers.SAXParserFactory


  Parser
  Value


  Xerces
  org.apache.xerces.jaxp.SAXParserFactoryImpl




javax.xml.parsers.DocumentBuilderFactory


  Parser
  Value


  Xerces
  org.apache.xerces.jaxp.DocumentBuilderFactoryImpl




javax.xml.transform.TransformerFactory


  XSLT Processor
  Value


  Xalan
  org.apache.xalan.processor.TransformerFactoryImpl


  Xalan bundled in JDK 1.5
  com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl


  Xalan XSLTC
  org.apache.xalan.xsltc.trax.TransformerFactoryImpl


  Saxon 6.x
  com.icl.saxon.TransformerFactoryImpl


  Saxon 7.x and 8.x:
  net.sf.saxon.TransformerFactoryImpl




Guidelines for Technical Writing
2009-10-09T14:46:00.007+09:00

Developer guide and education is more important than expected to the learning curve and performance of the application developer.


Use formal style in statement.

. Try to use intuitive and easy-to-read statement.
. Try to use exact and consistent words and terms.


Write guidelines from the viewpoint of application developer.

. Don't describe framework internal which application developers may not know.
. Keep consistent viewpoints.


Design the subjects and overall structure before writing details.

. Write down the table of contents first.


Adopt overview and detail pattern.

. There are patterns also in documentation.


Use lists and tables as possible.

. Lists are effective for describing process, arranging important points and cautions.
. Tables are effective for summarizing key-value style or hierarchical contents.


Don't use images as possible.

. Images are hard to maintain and update.
. Images are easy to understand at first sight but tend to shade details and exactness.
. Images are prone to waste volume of documents and make it difficult to transform documents.


Use non-trivial and consistent examples.

. Trivial examples can't make developers move fast to actual application.
. Examples should be flexible and scalable as the framework grows.
. Think of PetClinic sample appl. in spring framework's reference and PetStore sampl appl. in iBATIS' manual.


Try to derive and find out principles and techniques for excellent documentation.

. Be creative.


Establish effective and efficient documentation system.

. Think of docbook, wiki or other solutions and best practices.




Performance of iBATIS
2009-09-30T23:54:00.012+09:00
Lock occurs at com.ibatis.common.beans.ClassInfo#getInstance in case of cacheEnabled = true

In heavy traffic , lock occurs at com.ibatis.common.beans.ClassInfo#getInstance in case of cacheEnabled = true.
It seems to be happend because of "double synchronized"


https://issues.apache.org/jira/browse/IBATIS-508?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12683961



The following is interesting article related to the above issue. 


http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html


The above article says that we'd better use java.util.concurrent.ConcurrentHashMap (in JDK 5) rather than Collections.synchronizedMap, Hashtable or synchronized block.


Here is another article worth reading.


http://www.sun.com/bigadmin/features/articles/jvm_tuning_study.jsp#Ibatis





Race conditions in Throttle lead to thread blockage popping items from ThrottledPools under stress.

com.ibatis.common.util.Throttle seems to be a mechanism for iBATIS to control concurrent load, but causes few problems. Throttle is removed entirely in 2.3.1.


https://issues.apache.org/jira/browse/IBATIS-249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12491675







The test I involved showed 20% enhancement of throughput under high congestion after removing wait and notify from com.ibatis.common.util.Throttle and applying ConcurrentHashMap to com.ibatis.common.beans.ClassInfo.getInstance(). The tested application was stock trading application which had about 12,000 lines in all and consisted of 8 stateless local session beans using iBATIS 2.3 for data access. The application had about 12,000 lines. The application was on a IBM machine which had 10 PowerPC POWER6 CPUs and 16GB RAM. The stress test showed 2,400TPS before and 2,900TPS after the fixing.



Oracle BLOB/CLOB Handling of iBATIS
2009-09-30T10:33:00.005+09:00

The followings are tested and applied with iBATIS 2.3 and Oracle 10g. In case of iBATIS 3, is there anyone who tested the same thing ?




Oracle CLOB columns can be mapped string fields like VARCHAR2 columns without additional type handler or explicit Java/JDBC type description. In fact this feature is completely the benefit of enhancement of Oracle JDBC driver. Oracle JDBC driver higher than 10.2 provides functionality to handle CLOB column like varchar cloumn and it will work with Oracle database 9i as well as Oracle database 10g or higher. About this you can refer the following article.


http://www.oracle.com/technology/sample_code/tech/java/codesnippet/jdbc/clob10g/handlingclobsinoraclejdbc10g.html





Oracle BLOB column can be mapped byte[] field without custom handler using JDBC type and Java type description in result map definition or parameter map definition. This feature needs iBATIS 2.0.9 or higher and recent Oracle JDBC driver.
Unlike the above article, the javaType="[B" should be described explicitly in my case.

http://opensource.atlassian.com/confluence/oss/display/IBATIS/How+do+I+use+a+BLOB+or+CLOB




Session Limits on Oracle
2009-09-29T18:25:00.004+09:00
Oracle manages the global(instant level) limit for concurrent session and can be configured to manage per-user session limit through profile


Global concurrent session limit

The SESSIONS of initialization parameter specifies the max. number of sessions that can be created in the system at the same time. The OPEN_CURSORS and SESSIONS specify the max. number of concurrent open cursors for the system.


http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/initparams191.htm#i1133629
http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/initparams138.htm#CHDFEAFG






Per-user concurrent session limit

Using profile, Oracle can be configured to manage resource limits to a specific user. The configurable resources include SESSIONS_PER_USER, CPU_PER_SESSION, CPU_PER_CALL, and so on.


http://download.oracle.com/docs/cd/B19306_01/network.102/b14266/authoriz.htm#i1009631
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_6010.htm#i2065930



Tips on WebSphere
2009-09-22T12:27:00.032+09:00
Articles on WebSphere


Using Spring and Hibernate with WebSphere Application Server

Get the most out of your open source environment using WebSphere Application Server V6 through V7.



Characteristics of WebSphere
Transaction timeout of JTS doesn't throws any exception.

JTS throws no exception when transaction timeout occurs and so, the transaction would not roll-backed only with transaction timeout. The method timeout or something else should notify the container to roll-back the transaction.
This is explicitly documented with WebSphere 5.1, but 7.0 seems to have same feature.
http://publib.boulder.ibm.com/infocenter/wasinfo/v4r0/topic/com.ibm.support.was40.doc/html/Java_Transaction_Service__JTS_/swg21207635.html

JBoss 4.2 has the same behavior with it's default JTA (com.arjuna.ats.jbossatx.jta.TransactionManagerService) in the default config. I can't find any plausible parameter to change the behavior. (Is there anyone who knows whether it is the specified behavior for transaction timeout in JTA or JTS specification.)



The container throws org.omg.CORBA.TRANSACTION_ROLLBACK exception which can't nest the cause to itself.

When the unchecked exception is thrown in enterprise bean, the container intercepts it and throw TRANSACTION_ROLLBACK exception to remote client. The TRANSACTION_ROLLBACK can't nest the cause exception, so, the client can't trace the whole stack of the exception.
This would be critical to architectures of which the front layer draws all the exceptions and handle them, because the real exception can't be delivered to front layer.
This is explicitly documented with WebSphere 5.1, but 7.0 seems to have same feature.
http://publib.boulder.ibm.com/infocenter/wasinfo/v4r0/topic/com.ibm.support.was40.doc/html/WebSphere_Application_Server/swg21110173.html

The above problem can be solved by explicitly specifying JDBC level statement timeout.

In case of using iBATIS, you can specify the sql-map client scope value using defaultStatementTimeout attribute of setting element in sqlmap-config.xml file, or statement scope value using timeout attribute of select, update, delete or insert element of each sql map file.
If you are not using iBATIS or something like it, I think you may specify global value using JDBC driver specific parameter.



The container starts loading apache commons-logging configured to JDK logging.

This is in fact not a bug but a really normal case. The application that use apache commons-logging has to load its own commons-logging module by configuring the class loader priority and providing its own commons-logging.properties file.

http://publib.boulder.ibm.com/infocenter/wasinfo/v6r0/index.jsp?topic=/com.ibm.websphere.express.doc/info/exp/ae/ctrb_classload_jcl_conf.html



The container wrapping run-time exception from the local enterprise bean into UnknownLocalException which is a subclass of EJBException.

The following article from IBM say this is according to EJB 2.0 specification. I haven't checked this with other J2EE server like WebLogic or JBoss.
http://www-01.ibm.com/support/docview.wss?uid=swg21199310




Naming Service

   Accessing naming context for server cluster.
   Looking up an EJB home or business interface with JNDI.



Startup Beans
With startup beans of WebSphere, you can make some specific logic would be executed in the startup time or stop time. You can use startup beans at application level or module level.

   WebSphere Application Server v6 Startup Beans
   WebSphere Application Server Version 7.0 - Startup Beans



Questions
2009-09-15T10:12:00.004+09:00
Questions ???



How to combine two beans at design time in different container. (2009-09-15)




Tips on Maven
2009-09-05T13:29:00.077+09:00
Overview


  Maven Getting Started Guide : http://maven.apache.org/guides/getting-started/index.html
  POM Reference : http://maven.apache.org/pom.html



  Maven Build Lifecycle : http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html
  Maven Plugin List : http://maven.apache.org/plugins/
  Maven Shared Components : http://maven.apache.org/shared/
  mvn Command Line Options : http://www.sonatype.com/books/mvnref-book/reference/running.html#running-sect-help-option




Readings : references, tutorials and articles


  XML Schema and description for Maven POM file(maven-4.0.0.xsd).
  Maven Model 3.0 API
  Maven Core 3.0 API
  API of MavenProject class
  The mvn Command


Sonatype books

  Maven the Complete Reference
  Developing with Eclipse and Maven
  Maven by Example
  Maven Cookbook
  Repository Management with Nexus


Maven assemblies

   Guide to creating assemblies
   Maven Assembly Descriptor Reference
   Maven the Complete Reference/Maven Assemblies


Maven snapshot repositories


Repository - SNAPSHOT Handling
Maven Concepts Repositories
Guide to deploying 3rd party JARs to remote repository
Setting Up a Maven Repository


Deployment process and security


  <servers> element in settings.xml
  Password encryption
  Maven Wagon
  Uploading a directory using sftp with Maven



Site process


  Creating a site
  XML Schema Reference for the site descriptor
  Configuring the site descriptor
  Maven Project Info Reports Plugin
  Customizing Site Appearance
  Doxia Modules Guide
  doxia-module-markdown
  How to use confluence format? (in Maven site generation)



Release process


  Using the Maven Release plugin: Things to know
  Archiva Release Process (Real-world sample of Maven release plugin)


Property and Interpolation


  POM Expression evaluation




misc

  Multiple Module Projects with Eclipse
  Attach Library Sources and Javadocs

Guides to download sources and javadocs of artifacts
  Running Maven Checkstyle plugin safely with multi module project.

Using just propertyExpansion much simpler than http://maven.apache.org/plugins/maven-checkstyle-plugin/examples/multi-module-config.html
  Defining custom Maven build command for any project.

Specify ${project_loc} at 'Base directory' field and select 'Run' item at 'Display in favorites menu' field in 'Common' tab.
  reportPlugins doesn't inherit more information from pluginManagement.
  Naked Objects' Sister Projects 1.0: Developers Guide
  How do I get m2eclipse to recognize $M2_OPTS?







Referencing Maven project properties of List type


//@todo



This syntax works within pom.xml and Ant build files using Maven Ant plugin. But this doesn't working with resource filtering of Maven. I can't find any explain or reason for this. Is it a bug?


   ...
   <artifact:pom id="this-pom" file="${basedir}/pom.xml"/>
   <xsddoc out="${this-pom.reporting.outputDirectory}/xsddocs"
      verbose="true">
      <fileset dir="${this-pom.build.resources[0].directory}" 
         includes="**/*.xsd"/>
   </xsddoc>
   ...



Build Lifecycle, Build Phase, Plugin and Goal




  Plugin Prefix Resolution
  




Simple tips and troubleshooting


  The value of Maven property "project.build.directory" in normal case is ${basedir}/target. You can confirm this using the following command line : "mvn help:evaluate -Dexpression=project.build.directory".
 
  



  Solving "org.apache.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 60" exception when running site:site goal

Simply add a dependency on a newer version(eg. 3.8) of icu4j
  Solving "[ERROR] Unable to determine if resource ... exists in .." error.

Or just add <dependency.locations.enabled>false</dependency.locations.enabled> into the <properties> element of POM file.
    
  Using <addClasspath> when you have no dependencies fails with FileNotFoundException

Configuring to add classpath to MANIFEST file can cause unreasonable exception when running maven-jar-plugin without compile or run-time scope dependency. If you run package with -X option, you can identify exception whose stack goes like this.




  




Dependency on local library not in Maven repository and with no POM file


Sometimes your project may have dependency on a JAR file that is not registered to any of Maven repositories and so have no it's own POM file. In this case, you can use <systemPath> element to specify your module's dependency on it.



Note that systemPath could be specified only with system scope. You should specify groupId, artifactId, and version 'cause they are mandatory but you can specify any value and don't need pom file.


Escaping expression interpolation

It may necessary not to interpolate Maven expression in resources. In other words, you just want to leave ${some-property} as it is. For this, you can specify the escape string with escapeString parameter of maven-resource-plugin. You can also define maven.resources.escapeString property in your POM file.


For more refer this page : http://maven.apache.org/plugins/maven-resources-plugin/resources-mojo.html#escapeString



Client configuration


The location of client configuration files for subversion is dependent on operating system.


  Windows : %USERPROFILE%\Application Data\Subversion\config
  Linux : ~/.subversion/config


Configurable options are described here : http://svnbook.red-bean.com/en/1.5/svn.advanced.confarea.html#svn.advanced.confarea.opts.config



Working with Subversion working copy in format of ver. 1.7


The default configuration of Maven release plugin(maven-release-plugin) up to ver. 2.2.2 or Maven scm plugin(maven-scm-plugin) up to ver. 1.6 can't work correctly with Subversion working copy in format of ver. 1.7.

To solve this problem, you should override the configuration of release plugin or scm plugin to use maven-scm-provider-svnjava and svnkit 1.7.





For now, svnkit 1.7 has no release and is in snapshot version.


If you let the plugins use svnkit 1.3.x which is default setting as of now, you would meet the exceptions like the following.





For more, refer the followings,

  Maven SCM Subversion Provider - Java Impl.
  
  svnkit download
   




Loading Log4j Configuration File at Custom Position
2009-08-15T01:49:00.010+09:00

Log4j automatically loads configuration file named log4j.properties or log4j.xml on one of top directories in classpath at initialization. For example, if your classpath is /foo:/foo/bar.jar, /foo/log4j.properties would be automatically configured.

But if you should use different name or position, for example /foo/log4j-test.properties or /foo/baz/qux/log4j.properties, there are two methods.

Using log4j.configuration system property

Load the application specifying explicitly the Log4j configuration file to use using log4j.configuration system property.
java -Dlog4j.configuration=baz/qux/log4j.properties MyApplication.java


Note that the value should be relative to classpath. It is not /foo/baz/qux/log4j.properties but baz/qux/log4j.properties.


Using Configurator.configure method

Before configruing proper Configurator, call static LogManager.resetConfiguration method.
import org.springframework.core.io.ClassPathResource;
...
Properties props = new Properties();
props.load((new ClassPathResource("baz/qux/log4j.properties"))
           .getInputStream());
org.apache.log4j.LogManager.resetConfiguration();
org.apache.log4j.PropertyConfigurator.configure(props);  



about SqlMapClientFactoryBean of Spring Framework
2009-08-13T11:09:00.008+09:00

SqlMapClientBean of springframework creates SqlMapClient with EXTERNAL transaction management by default and internally wrap the given data source to TransactionAwareDataSourceProxy.

So, the typical setup for iBATIS SqlMapClient bean in spring configuration would be like the following.


<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
 <property name="driverClassName" value="oracle.jdbc.OracleDriver" />
 <property name="url" value="jdbc:oracle:thin:@127.0.0.1:1521:XE" />
 <property name="username" value="_user_" />
 <property name="password" value="_passwd_" />
 <property name="defaultAutoCommit" value="true" />
 <property name="maxActive" value="10" />
 <property name="maxIdle" value="10" />
 <property name="minIdle" value="0" />
 <property name="initialSize" value="10" />
</bean>

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
 <property name="dataSource" ref="dataSource" />
 <property name="defaultTimeout" value="120" />
</bean>
 
<tx:annotation-driven 
 transaction-manager="transactionManager"
 mode="proxy"
 proxy-target-class="true"
/>

<bean id="sqlMapClient" class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
 <description>default SqlMapClient bean for DAOs</description>
 <property name="configLocation" value="classpath:_pathto_/sql-map.xml" />
  
 <property name="dataSource" ref="dataSource" />
 <!-- Default setting is specified for clarity. -->
 <property name="useTransactionAwareDataSource" value="true"/>
 <!-- Default setting is specified for clarity. -->
 <property name="transactionConfigClass">
  <value type="java.lang.Class">com.ibatis.sqlmap.engine.transaction.external.ExternalTransactionConfig
 </property>

</bean>


At the above sample, the default setup for useTransactionAwareDataSource and transactionConfigClass properties is specified for clarity.

ExternalTransactionConfig would set the "SetAutoCommitAllowed" property of SqlMapClient to false, in contrast to the iBATIS default, to always keep the original autoCommit value as provided by the connection pool.

For more information, refer API documentation of SqlMapClientFactoryBean, specially setDataSource, setUseTransactionAwareDataSource, and setTransactionConfigClass methods.



Hierarchical Queries
2009-07-30T21:25:00.024+09:00

There are two types of hierarchical queries handling tree structure data in adjacency list model. (table has recursive relationship using foreign key on parent_id column)

One is (START WITH) CONNECT BY clause provided by Oracle and the other is recursive WITH clause(recursive common table expressions).

Although CONNECT BY clause is much more intuitive, robust and simple, WITH clause is ANSI-SQL standard syntax.


CONNECT BY clause

Supported by : Oracle 9i +, DB2 9.7 (the latest version)
Hierarchical Queries of Oracle Database 10g


SELECT ~ 
FROM ~ 
WHERE ~
START WITH parent_id IS NULL
CONNECT BY PRIOR id = parent_id


Recursive WITH clause

Supported by : DB2, SQL Server 2005+, PostgreSQL 8.4 (the latest version)
ANSI-SQL syntax

http://www.ibm.com/developerworks/data/library/techarticle/dm-0510rielau/


http://msdn.microsoft.com/en-us/library/ms175972.aspx


http://www.postgresql.org/docs/8.4/interactive/queries-with.html

 

Examples by Database

The structure of the table for the example statements below is defined by the following DDL.

create table category(
 id varchar2(10) not null,
 name varchar2(60) not null,
 parent_id varchar2(10),
 seq number(5, 0),
 descn varchar2(2000),
 constraint pk_category primary key (id),
 constraint fk_cateogry_1 foreign key (parent_id) references category(id)
);


Oracle 9i or higher

The basic query is : 
select id, name, parent_id, seq, descn, 
from category
start with parent_id is null
connect by prior id = parent_id



Oracle 9i provides LEVEL pseudo-column, SYS_CONNECT_BY function and ORDER SIBLINGS BY clause which can be used in hierarchical queries.

select id, name, parent_id, seq, level, descn, 
       sys_connect_by_path(id, '//') as id_path,
       sys_connect_by_path(name, '//') as name_path
from category
start with parent_id is null
connect by prior id = parent_id
order siblings by seq, name



Oracle 10g provides additional CONNECT_BY_ISLEAF pseudo-column, CONNECT_BY_ISCYCLE pseudo-column and CONNECT BY NOCYCLE. 
select id, name, parent_id, seq, level, descn, 
       sys_connect_by_path(id, '//') as id_path,
       sys_connect_by_path(name, '//') as name_path,
       connect_by_isleaf as is_leaf
from category
start with parent_id is null
connect by nocycle prior id = parent_id and level >= 5
order siblings by seq, name


Microsoft SQL Server 2005 or higher

The basic hierarchical query is 

with v_category("id", "name", "level", parent_id) as (
   select "id", "name", 1 as "level", parent_id
   from category 
   where id is null
   union all
   select a."id", b."level" + 1, a.parent_id
   from category as a inner join v_category as b on a.parent_id = b."id"
)
select "id", "name", "level", parent_id
from v_category



Readings


Adjacency list model


Subquery factoring in Oracle 9i


Recursive Subquery Factoring Examples of Oracle 11.2

Oracle at last added recursive feature to existing with clause.


DB2 9.7: Run Oracle applications on DB2 9.7 for Linux, Unix, and Windows



misc

MySQL (up to 6.0, latest version) still doesn't support hierarchical query.




About Tomcat
2009-06-26T13:27:00.003+09:00
Resources


The Context Container for Tomcat 5.5


Class Loader of Tomcat 5.5


How do I configure Tomcat to support remote debugging?


FAQ for Tomcat and Eclipse WTP(Web Tools Platform)







Useful Tools for PDF Files
2009-06-24T00:59:00.004+09:00
Tweak PDF

Homepage : http://www.coolpdf.com/tweakpdf.html
Current Ver. : 1.33
Feature : (from homepage)

With the freeware utility Tweak PDF, you are allowed to set the initial view preferences of a PDF document, such as whether to center window of the PDF file when opened, whether to display document title, to fit window, to hide menubar, to hide toolbar, and to hide window UI. When window UI is made hidden, a PDF file is just like a PowerPoint slide zoomed to full screen. You can even set the page mode of a PDF document, such as show PDF files in full screen mode, outlines mode, thumbnail mode, or simply without any special mode. Page Layout also comes as an option for you to tweak. PDF document properties such as title, subject, author, keywords can be modified with Tweak PDF.



You can even tweak PDF version from 1.0 to 1.5 for compatibility concerns, and shrink PDF files by setting the compression level and choosing the compression algorithm.




Free PDF Writer

Homepage : http://www.pdfill.com/freewriter.html
Current Ver. : 6.0
Feature : (from homepage)

- PDF Optimization

- PDF Description

- PDF Security

- PDF View Preference

- PDF Presentation

- PDF Rotate and Crop

- Output Options

- Post Process Options




Free PDF Tools

Homepage : http://www.pdfill.com/pdf_tools_free.html
Current Ver. : 6.0
Feature : (from homepage)

- Merge

- Split and Reorder

- Encrypt and Decrypt with Security Options

- Rotate and Crop

- Reformat

- Header and Footer

- Watermark by Stylized Text

- Watermark by Image

- Convert Images to PDF

- Convert PDF into images

- PDF Form Fields: Delete, Flatten, List

- Convert  PostScript(PS) File into PDF





Readings on Tuning
2009-06-18T02:57:00.011+09:00
Readings on Tuning General with Java


  Java command line debug options
  Debugging with the Maven Jetty Plugin in Eclipse
  Uncovering Memory Leaks Using NetBeans Profiler
  Java memory leaks -- Catch me if you can (2006)
  IBM Monitoring and Diagnostic Tools for Java - Health Center




Oracle JDBC Driver Tuning
When tuning application which connect database using Oracle JDBC driver, you should refer the following documents.


Oracle 10.2 JDBC Developer's Guide and Reference/Statement Caching
Oracle 10.2 JDBC Developer's Guide and Reference/Implicit Connection Caching
Oracle 10.2 JDBC Developer's Guide and Reference/Performance Extensions
Oracle 10.2 JDBC Developer's Guide and Reference/OCI Connection Pooling
Oracle 10.2 JDBC Developer's Guide and Reference/Coding Tips




JBoss Tuning


  Tuning and Slimming JBossAS
  
  JBoss Performance Tuning part 1
  
  JBoss Performance Tuning part 2
  




WebSphere Tuning


  WebSphere AS 7.0 Performance Tuning
  
  OS Tuning for WebSphere AS 7.0
  



WebLogic Tuning


  WebLogic 10.3 Performance and Tuning
  
  WebLogic 9.2 Performance and Tuning
  




Linux Tuning


  System Tuning Info for Linux Servers
  



Windows Tuning


  Windows 2000 Performance Tuning
  



About JForum
2009-04-21T15:50:00.008+09:00
Limitation(as of version 2.1.8)

Doesn't support inlined images.
Doesn't support wiki formatting.
Doesn't support xhtml template perfectly. : Seems to need lots of customization.
Doesn't support inlined SVG(Scalable Vector Graphics) part(<svg></svg>).


Tips

Removing links to moved topics in the original forum : http://www.jforum.net/posts/preList/4195/17273.page





Removing preceding clip icon for the topics which have attachments in topic listing page : 

Comments out the following line in templates/default/forum_show.htm file.

<#if topic.hasAttach() && attachmentsEnabled>
<img src="${contextPath}/templates/${templateName}/images/icon_clip.gif" align="middle" alt="[Clip]" /></#if>





SQL Comments Syntax for Oracle, DB2, MySQL and so on
2009-04-08T22:12:00.005+09:00



DBMS
Block Comments
Line Comments


Oracle
/* comments text */
-- comments text


DB2
 
-- comments text


SQL Server (2000+)
/* comments text */
-- comments text


MySQL (4.0+)
/* comments text */

  -- comments text

  # comments text



PostgreSQL
/* comments text */
-- comments text






Actually /* */ and -- are SQL standard syntax and have following characteristics.
Block Comments

Format : /* comments text */
Can be located any position of statement.
Can span multiple lines.
Can be nested.


Line Comments

Format : -- comments text
Can start in the middle of line but always extends to the end of line.
Can't span multiple lines.
Needs at least single space after '--'



Remarkable Eclipse Plugins
2009-04-07T15:37:00.024+09:00


   Plug-in
   Site
   Description


   SpringSource Tool Suite
   http://www.springsource.com/developer/sts
   
      
      Spring framework development tools
      
   


   Hibernate Tools for Eclipse and Ant
   http://www.hibernate.org/subprojects/tools.html
   
      
      Hibernate development tools
      
   


   AJDT
   http://www.eclipse.org/ajdt/
   
      
      AspectJ development tools
      
   


   Google Plugin for Eclipse
   
      http://code.google.com/appengine/docs/java/tools/eclipse.html
   
   
      
      development tools for GWT and Google App Engine
      
   


   Vex
   
      http://marketplace.eclipse.org/content/vex/click
   
   
      
      visual editor for XML
      
   


   Mylyn WikiText
   
      http://wiki.eclipse.org/Mylyn/WikiText
   
   
      
      tools for parsing, editing and presenting lightweight markup
      
   


   m2eclipse
   http://eclipse.org/m2e/
   
      
      Maven plug-in
      
   


   Subclipse
   http://subclipse.tigris.org/
   
      
      Subversion client
      
   


   DBViewer Plugin
   http://www.ne.jp/asahi/zigen/home/plugin/dbviewer/
   
      
      General database client
      
   


   jOra
   http://jora.luenasoft.de/
   
      
      Oracle database client
      
   


   JadClipse
   http://sourceforge.net/projects/jadclipse/
   
      
      Java decompiler
      
   


   LogViewer
   http://code.google.com/a/eclipselabs.org/p/logviewer/
   
      
      File viewer
      
   


   Properties Editor
   http://propedit.sourceforge.jp/index_en.html
   
      
      File editor
      
   


   JDepend4Eclipse
   http://andrei.gmxhome.de/jdepend4eclipse/
   
      
      Code analysis
      
   


   Regex Util
   http://myregexp.com/eclipsePlugin.html
   
      
      testing/editing regular expressions flavor of the Sun Java standard API (java.util.regex)
      
   


   Eclipse Hex Editor Plugin (EHEP)
   http://ehep.sourceforge.net/
   
      
      File editor
      allows user to view or modify any file in hex mode.
      
   


   Eclipse launcher for VisualVM
   http://visualvm.java.net/eclipse-launcher.html
   
      
      monitoring and profiling Eclipse projects using VisualVM
      
   




jOra

Oracle Database Client


This program provides not only typical components for application programmer such as schema browser, SQL editor and executor but also some components for DBA such as session viewer and parameter viewer.

This program is for only Oracle database and so provides Oracle friendly components, stored procedure editor and PL/SQL editor.


Components are :

Connections View
Database Explorer
Schema Browser
SQL Worksheet
SQL Script Editor
SQL History
SQL Monitor
DMBS Output-View
Stored Procedure Editor
PL/SQL Editor
Outline View
Sessions View
Parameters View


You can find more detailed features in this page. but it is in German.



M2Eclipse


As of me, the previous plugin M2Eclipse(http://m2eclipse.sonatype.org/) by Sonatype is still better than the current m2e(http://eclipse.org/m2e/) by Eclipse.


To get the last M2Eclipse by Sonatype, access the following update sites.


  Maven Integration for Eclipse Update Site : http://m2eclipse.sonatype.org/sites/m2e/
  Maven Integration for Eclipse Extras Update Site : http://m2eclipse.sonatype.org/sites/m2e-extras/




Comparisons of Collaborative Software
2009-04-07T13:51:00.003+09:00
The Definition : 'Collaborative Software'



Comparison of major Wiki softwares : TWiki, Confluence, XWiki



Object Detection of JavaScript
2009-04-07T03:25:00.010+09:00

When you need to check the existence of the specific property or method of an object before you use it, you can use if statement like followings.


...
<script>
function iniPage(){

   // forms with name of 'upload' is expected to have file type input by convention.
   if(this.document.forms['upload']){
      this.document.forms['upload'].enctype = "multipart/form-data";
   }
   ...
}

function onSubmit(form){
   //if recordSubmit function is defined.
   if(window.recordSubmit && form.name){
      window.recordSubmit(location.host, hocation.pathname, form.name);
   }
   ...
}
...
</script>



At the first function, if a form with name of 'upload' exists, its enctype would be set to multipart/form-data. At the second function, if 'recordSubmit' is defined in the script and the delivered parameter has 'name' property, the 'recordSubmit' function will be executed before form's submit.



If(condition) statement returns false when the 'condition' corresponds one of the followings.


Logical false, Null, 0, Empty string, Object doesn't exist, Undefined property




For primitive type or string type properties, if statement also returns false in case of their value is zero or empty. So, it is more clear and safe to use typeof operator and if statement all together.

...
<script>
function onMakeOrder(form){

   if(typeof form.elements['requestDate'] != "undefined"){
      if(!isValidRequestDate(form.elements['requestDate'].value)){
         alert("The request date is not valid");
         return false;
      }
   }
   ...
}

</script>



Useful Shortcuts of Eclipse
2009-04-05T22:19:00.011+09:00


  Binding
  Command
  When
  Description


  F5
  Refresh
  In Windows
  
    
    Refresh the selected items
    
  


  Ctrl + Space
  Content Assist
  In Dialogs and Windows
  
    
    Popup to provide contextual proposals
    
  


  Ctrl + I
  Indent Line
  Editing Java Source
  
    
    Adjust indentations of lines in selected block
    
  


  Ctrl + L
  Go to Line
  Editing Text
  
    
    Go to a specified line of text
    
  


  Ctrl + G
  Declaration in Workspace
  Editing in Structured Text Editors
  
    
    Search for declarations of the selected element in the workspace
    
  


  Ctrl + /
  Toggle Comment
  
    Editing SQL, Editing Properties Files, 
    Editing JavaScript Source, Editing Java Source
  
  
    
    Toggle comment the selected lines
    
  


  Ctrl + Shift + F
  Format
  Editing in Structured Text Editors
  
    
    Format selection
    
  


  Ctrl + Shift + G
  References in Workspace
  In Windows
  
    
    Search for references to the selected element in the workspace
    
  


  Ctrl + Shift + M
  Add Import
  Editing Java Source
  
    
    Create import statement on selection
    
  


  Ctrl + Shift + R
  Open Resource
  In Windows
  
    
    Open an editor on a particular resource
    
  


  Alt + Shift + J
  Add Javadoc Comment
  In Windows
  
    
    Add a Javadoc comment stub to the member element
    
  


  Alt + Left
  Backward History
  In Windows
  
    
    Activate previous resource in editor history.
    
  


  Alt + Right
  Forward History
  In Windows
  
    
    Activate next resource in editor history.
    
  




More readings

  10 Eclipse Navigation Shortcuts Every Java Programmer Should Know



About MySQL on Red Hat Enterprise Linux 4
2009-03-25T11:09:00.007+09:00
Checking Installation
Use rpm command like following
root# rpm -q -a | grep mysql
mysql-server-4.1.12-3.RHEL4.1
mysql-4.1.12-3.RHEL4.1
php-mysql-4.3.9-3.8
mysql-devel-4.1.12-3.RHEL4.1


Installed Directory

Server program : /etc/init.d/mysql
Client programs (mysql, mysqladmin, mysqlshow, and so on) : /usr/bin/
Default config file : /etc/my.cnf
Data files : /var/lib/mysql/


Starting Server
Use the following command 
root# /sbin/chkconfig mysqld on
root# /etc/init.d/mysqld start
root# ps -ef | grep mysql

The command executed by root account would delegate the execution of /usr/libexec/mysqld to mysql account.

Stopping Server
Use the following command.
root# /etc/init.d/mysqld stop



Resetting Root Password
When you forgot password of root user in MySQL, you can use the following commands after stopping the running process of mysqld if any.
mysql# /usr/bin/mysqld_safe --skip-grant-tables &
mysql# /usr/bin/mysqladmin -u root flush-privileges password "newpasswd"

After that restart the server in normal mode and you can connect as a root user using newpasswd.

For more information, refer formal documentation of MySQL : How to Reset the Root Password


Comparison of HSQLDB, H2, SQLite
2009-03-17T12:38:00.028+09:00


  Item
  HSQLDB (1.8)
  H2(1.1.109)
  SQLite (3.6.22)


  Lanaguage
  Java
  Java
  C


  Supports Client/Server Mode
  Yes
  Yes
  No


  Supports Embedded Mode
  Yes
  Yes
  Yes


  Supports In-Memory Databases
  Yes
  Yes
  Yes


  Provided Transaction Isolation Mode
  Read Uncommitted
  Read Committed, Serializable
  Unclear


  Supports Foreign Key Constraint
  Yes
  Yes
  Yes
(≥ 3.6.19)


  Supports View Object
  Yes
  Yes
  Yes


  Supports Sequence Object
  Yes
  Yes
  No


  Supports User-defined Procedure/Function
  Yes
  No
  No


  Supports Trigger
  Yes
  Yes
  Yes


  Supports Inner Join
  Yes
  Yes
  Yes


  Supports Left Outer Join
  Yes
  Yes
  Yes


  Supports Right Outer Join
  Yes
  Yes
  No


  Supports Full Outer Join
  Yes
  Yes
  No


  Supports ORDER BY Clause
  Yes
  Yes
  Yes


  Supports GROUP BY/HAVING Clause
  Yes
  Yes
  Yes


  Supports Paginated Query
  Yes
(offet m fetch n lows)
  Yes
(limit n offset m)
  Yes
(limit n offset m)



  Provides C API
  No
  No
  Yes


  Provides JDBC Driver
  Yes
  Yes
  by 3rd party


  Provides ODBC Driver
  under development
  Yes
  No


  Explicitly Supported by Hibernate 3.3
  Yes
  Yes
  No


  Explicitly Supported by DbUnit 2.4
  Yes
  Yes
  No


  Explicitly Supported by Power*Architect 0.9.13-RC1
  Yes
  No
  No






Other comparisons

  Database Comparison Table : H2, HSQLDB, DERBY, PostgreSQL, MySQL by Sukhvinder Singh






Features of HSQLDB (1.8)
from http://hsqldb.org/web/hsqlFeatures.html

JAVA

    100% Java
    Support JDK 1.1.x, 1.2.x, 1.3.x, 1.4.x, 1.5.x, 1.6.x
    Extensive JDBC interface support with batch statement and scrollable ResultSet functionality
    Full JDBC DatabaseMetaData and ResultSetMetaData support
    Java stored procedures and functions
    Full support for PreparedStatement objects to speed up query processing 

SQL

    Relational Database Management System, with the object capabilities of Java
    Very extensive support for SQL:2003 Standard syntax, including most optional features
    Supports all base data types of the SQL Standard, including BINARY, BIT, BOOLEAN, date-time, INTERVAL, BLOB, CLOB
    Supports user-defined DOMAIN types, including type constraints
    Fast SELECT, INSERT, DELETE, UPDATE and MERGE operations
    INNER, LEFT OUTER, RIGHT OUTER and FULL joins
    UNION, EXCEPT, INTERSECT, including use of parentheses, limits and offsets
    Scalar (single value) SELECTS, row and correlated subqueries including IN, EXISTS, ANY, ALL
    Views, Temp tables and sequences
    Primary key, unique and check constraints on single or multiple columns 
    Referential Integrity (foreign keys) on multiple columns with full cascading options (delete, update, set null, set default)
    ORDER BY, GROUP BY and HAVING
    COUNT, SUM, MIN, MAX, AVG and statistical aggregate functions
    Full support for SQL expressions such as CASE .. WHEN .. ELSE .. , NULLIF etc.
    SQL standard autoincrement column support plus sequences
    Transaction COMMIT, ROLLBACK and SAVEPOINT support
    Multiple schemata per database
    Triggers, implemented as Java classes, or as SQL statements
    Database security with passwords, user rights and roles with GRANT and REVOKE
    Extensive set of ALTER TABLE commands, including change of table column type 

Persistence

    In-memory tables for fastest operation
    Disk based tables for large data sets
    Text tables with external file data sources such as CSV files
    Disk tables (CACHED TABLE) up to 8GB and text tables up to 2GB each
    Size of each string or binary item only limited by memory
    Database dump as SQL script with or without data 

Deployment

    Embedded (into Java applications) and Client-Server operating modes
    Three client server protocols: HSQL, HTTP and HSQL-BER - can run as an HTTP web server - all with SSL option
    Can be used in applets, read-only media (CD), inside jars, webstart and embedded applications
    Multiple databases per JVM 

Utilities

    Powerful and compact java command line and GUI tools for database management
    Tranfer tool for conversion of databases to / from other popular database managment systems







Features of H2 (1.1.109)
from http://www.h2database.com/html/features.html

Main Features

    Very fast database engine
    Free, with source code
    Written in Java
    Supports standard SQL, JDBC API
    Embedded and Server mode, Clustering support
    Strong security features
    The PostgreSQL ODBC driver can be used
    Multi version concurrency

Additional Features

    Disk based or in-memory databases and tables, read-only database support, temporary tables
    Transaction support (read committed and serializable transaction isolation), 2-phase-commit
    Multiple connections, table level locking
    Cost based optimizer, using a genetic algorithm for complex queries, zero-administration
    Scrollable and updatable result set support, large result set, external result sorting, functions can return a result set
    Encrypted database (AES or XTEA), SHA-256 password encryption, encryption functions, SSL

SQL Support

    Support for multiple schemas, information schema
    Referential integrity / foreign key constraints with cascade, check constraints
    Inner and outer joins, subqueries, read only views and inline views
    Triggers and Java functions / stored procedures
    Many built-in functions, including XML and lossless data compression
    Wide range of data types including large objects (BLOB/CLOB) and arrays
    Sequence and autoincrement columns, computed columns (can be used for function based indexes)
    ORDER BY, GROUP BY, HAVING, UNION, LIMIT, TOP
    Collation support, users, roles
    Compatibility modes for IBM DB2, Apache Derby, HSQLDB, MS SQL Server, MySQL, Oracle, and PostgreSQL.

Security Features

    Includes a solution for the SQL injection problem
    User password authenticated uses SHA-256 and salt
    User passwords are never transmitted in plain text over the network (even when using insecure connections)
    All database files (including script files that can be used to backup data) can be encrypted using AES-256 and XTEA encryption algorithms
    The remote JDBC driver supports TCP/IP connections over SSL/TLS
    The built-in web server supports connections over SSL/TLS
    Passwords can be sent to the database using char arrays instead of Strings

Other Features and Tools

    Small footprint (smaller than 1 MB), low memory requirements
    Multiple index types (b-tree, tree, hash)
    Support for multi-dimensional indexes
    CSV (comma separated values) file support
    Support for linked tables, and a built-in virtual 'range' table
    EXPLAIN PLAN support, sophisticated trace options
    Database closing can be delayed or disabled to improve the performance
    Web-based Console application (English, German, partially French and Spanish) with autocomplete
    The database can generate SQL script files
    Contains a recovery tool that can dump the contents of the data file
    Support for variables (for example to calculate running totals)
    Automatic re-compilation of prepared statements
    Uses a small number of database files
    Uses a checksum for each record and log entry for data integrity
    Well tested (high code coverage, randomized stress tests)



Notable Maven Repositories, Plug-ins and Skins
2009-03-15T21:23:00.046+09:00

Maven Repositories

Sonatype Nexus Open Source Version

   http://repo.expertvill.net/

Main Repositories

   http://mvnrepository.com/

JBoss Maven Repository

    1. JBoss Maven Snapshot Repositories

    2. JBoss Maven Release Repositories

    JBoss Maven repsoitories include hibernate releases and snapshots.
  
SUN Jars Repository

    http://maven.apache.org/guides/mini/guide-coping-with-sun-jars.html
  
DocBook Repository

    http://docbook.sourceforge.net/maven/repository/

    About configuring pom.xml, refer http://wiki.docbook.org/topic/Maven.
  


Notable Maven plug-ins

  Resource Plugin : http://maven.apache.org/plugins/maven-resources-plugin/
  
  Eclipse Plugin : http://maven.apache.org/plugins/maven-eclipse-plugin/
  
  Doxia Plugin : http://maven.apache.org/doxia/doxia/doxia-maven-plugin/
  
  JBoss Plugin : http://mojo.codehaus.org/jboss-maven-plugin/
  
  Jetty Plugin : http://docs.codehaus.org/display/JETTY/Maven+Jetty+Plugin
  
  IzPack Plugin : http://izpack.codehaus.org/izpack-maven-plugin/
  
  Properties Plugin : http://mojo.codehaus.org/properties-maven-plugin/

Provides goals to read and write properties from and to files.
  
  Build Number Plugin : http://mojo.codehaus.org/buildnumber-maven-plugin/

Designed to get a unique build number for each time you build your project.
  
  Versions Plugin : http://mojo.codehaus.org/versions-maven-plugin/

Manages the versions of artifacts in a project's POM.
  
  Timestamp Plugin : http://code.google.com/p/maven-timestamp-plugin/

Provides formatted timestamps for maven builds.
  
  Spring BeanDoc Plugin : http://mojo.codehaus.org/maven-springbeandoc-plugin/

Generates pretty reports for Spring configuration files.
  
  Graphviz Plugin : http://graphviz-maven-plugin.bryon.us/

Uses the Graphviz library to render .dot files into images.
  
  Replacer Plugin : http://code.google.com/p/maven-replacer-plugin/

Replace tokens within a file with a given value and fully supports regular expressions.
  
  FreeMarker Pre Processor(FMPP) Plugin : http://code.google.com/p/freemarkerpp-maven-plugin/

Allows to process FreeMarker templates, inject data into those templates in order to produce code, artifacts, reports or anything desired. 
  
  Expression Plugin : https://github.com/jdcasey/expression-maven-plugin

Allow users to resolve expressions interactively.
  


Code analysis tools plug-in

  FindBugs Plugin : http://mojo.codehaus.org/findbugs-maven-plugin/
  Checkstyle Plugin : http://maven.apache.org/plugins/maven-checkstyle-plugin/

Generates a report regarding the code style used by the developers.
  
  Dependency Graph Plugin : http://el4j.sourceforge.net/plugins/maven-depgraph-plugin/

Draws a dependency graph of the project the mojo is executed in.
  
  Sonar Plugin : http://mojo.codehaus.org/sonar-maven-plugin/

Enables to analyze and report metrics on source code.
  


Collaboration tools plug-in

  Confluence Plugin : http://code.google.com/p/maven-confluence-plugin/

Documents a project (using maven site style) and send result to a live confluence site.
  
  Redmine Plugin : http://www.nuiton.org/embedded/jredmine/maven-jredmine-plugin/
  


Source configuration management tools plug-in

  SVN Revision Number Plugin : http://code.google.com/p/maven-svn-revision-number-plugin/

Retrieves the revision number and the status of the Subversion working copy directory and sets project properties that can be used later in the build process.
    
      To work with working copy of SVN 1.7 or higher, you should setup dependencies for this plugin to use svnkit 1.7.0-SNAPSHOT. For this refer : http://code.google.com/p/maven-svn-revision-number-plugin/issues/detail?id=10
      
    
  






Notable Maven skins

  Fluido skin : http://code.google.com/p/fluido-skin/

rounded corners and code syntax highlight



Tips on Ant
2009-03-09T01:08:00.047+09:00
Readings : References, Articles and Tutorials


  Ant Manual
  External Tools and Tasks



  Using Antlib props in Ant 1.8
  
  How can I do something like <property name="prop" value="${${anotherprop}}"/> (double expanding the property)?
  


Pattern to Specify Files and Directories

  
Ant User Manual : Directory-based Tasks



Notable Ant Tasks


  The Apache Ant Libraries Subproject

  Ant-Contrib Tasks
  Maven Ant Tasks
  WebLogic Server 9.0 Ant Tasks to configure and use a server domain
  WebLogic Server 11.1 Ant Tasks to configure and use a server domain
  WebLogic Server 11.1 Ant Tasks to deploy applications and modules : wldeploy

  Ant tasks for markup conversion in Mylyn WikiText
     
      API for MarkupToHtmlTask class.
      API for MarkupToDocbookTask class.
    
  Antelope
  Input task
  AntForm/AntMenu

  AntForm provides an Ant task (see usage) for setting property values through a Swing-based form.
  
  FMPP Ant task
  


Using Saxon in Ant XSLT Task

If you don't read the following article, you would do really lots of trial and error to use Saxon XSLT processor with XSLT task of Ant.


  
http://saxon.wiki.sourceforge.net/Calling+Saxon+from+Ant



Listing members of fileset or path-like structure line by line

For eye-checking or reporting purpose, sometimes it is necessary to list members of fileset each one in it's line.

You can do this using pathconvert and echo tasks.


The following is snippet used to list non-java files in source directories of Maven projects (which are multi-module form).



You can also list path-like structure line by line using <pathconvert> task.




Actually <pathconvert> can also be applied to dirset, filelist, or propertyset as well. For details, refer http://ant.apache.org/manual/Tasks/pathconvert.html


Including another path-like structure within a path-like structure

If you want include a path-like structure to another, you can use <path refid="..."> like this.




Note that you should not use <pathelement path="...">. The value of path attribute in pathelement is expected to be string corresponding to path not id of path-like structure.

The following would cause error.





If you really want to use pathelement all the way, you can use toString function.

The following would work.





Note that ${java.class.path} which can be evaluated from default system properties of Java is just string corresponding to classpath and maven.plugin.classpath which is defined implicitly with maven-antrun-plugin is id of path-like structure.

So, you should use them like the following.





Printing environment variables


To identify all the environment variables and their values defined within the process the current Ant build is running, you can use
echo task with environment attribute.





The above property task makes properties for all the environment variables in current process with the property names prefixed by 'env'.



DATE, TIME, and TIMESTAMP of SQL Standard
2009-02-28T14:06:00.009+09:00

The followings are definition of DATE, TIME, and TIMESTAMP data type of SQL standard.


These are somewhat confusing to Java developers, because Date class of JDK represents a specific instant in time, with millisecond precision and there's no basic classes(except java.sql.Date, java.sql.Time which are restricted to JDBC) that represent pure date and pure time separately.


-  DATE - contains the <datetime field>s YEAR, MONTH, and DAY;

-  TIME - contains the <datetime field>s HOUR, MINUTE, and SECOND;

-  TIMESTAMP - contains the <datetime field>s YEAR, MONTH, DAY, HOUR, MINUTE, 
               and SECOND.


The above definition is from SQL-92 standard draft which you can get from here.



Print Classpath in Ant Build File
2009-02-20T10:18:00.014+09:00
Sometimes, it can be convenient to print out classpath to console to confirm it is correctly setup in Ant build file.

For this, you can use the expression ${toString:pathreference} like the following example

<?xml version="1.0" encoding="UTF-8"?>
<project name="shop1-hibernate-export" default="echo-env" basedir="."
 xmlns:artifact="antlib:org.apache.maven.artifact.ant">

 ...

 <!-- Get Maven Dependency -->
 <artifact:pom id="project.pom" file="${project.home}/pom.xml"/>
 <artifact:dependencies pomRefId="project.pom" pathId="dependency.classpath"/>
 
 <!-- Ant4Eclipse Tasks Definitions -->
 <taskdef resource="net/sf/ant4eclipse/antlib.xml" /> 
 <getEclipseClasspath pathId="eclipse.classpath" project="../../../../../.."/>

 <path id="project.classpath">
  <path refid="dependency.classpath"/>
  <path refid="eclipse.classpath"/>
 </path>

 <target name="echo-env">
  <echoproperties/>
  <echo>${toString:project.classpath}</echo>
 </target>

 <target name="generate-ddl">

 </target>

</project>



Tips for OpenOffice.org 3
2009-01-21T10:02:00.011+09:00
Toggle off auto formatting of date string

Symptom : 

Date string such as 01/23, 2009-01-23, or 1.23 is converted to more natural date format automatically after typing.
Recipe : 

Go to [Tools > Options...] menu and select [OpenOffice.org Writer > Table] section. In the dialog, uncheck "Number recognition" option.


Bottom-line mismatch between pure English line and line containing both English and Asian letter.

....not solved


View page headings panel and styles/formatting panel

Check [Format > Styles and Formatting] menu
Check [Edit > Navigator] menu


Cascaded numbering for heading style

Use [Tools > Outline Numbering ...] menu
In Numbering tabs, you can assign number format (1, 2, 3, ..., A, B, C, ..., or i, ii, iii, ...), cascading level (1.1.1, 1.1.1.1 for example) and start number for each level. Levels from 1 to 10 correspond styles from Heading 1 to Heading 10 respectively.



Using Stored Procedure/Function with iBATIS
2008-12-19T11:30:00.030+09:00
This is simple example for using stored function with iBATIS.



Recently I implemented number generating module using oracle stored function and iBATIS with lots of trial/error more than I expected. It's because I couldn't find a complete working example. The example in official manual from iBATIS is not sufficient , the example from the book 'iBATIS in Action' is not correct(I didn't check the corrections from the Manning site), and the search results from Goole didn't include excellent examples for me.



The following exmaple is using number table to generate number for construct new primary key for specified table.



The number table has following structure
CREATE TABLE test.PS_NUMBER (
  table_name VARCHAR2(50) NOT NULL,
  next_no NUMBER(20) NOT NULL,
  CONSTRAINT pk_number PRIMARY KEY (table_name)
);

To prevent same number is given in highly concurrent situation with Oracle database, SELECT ~ FOR UPDATE should be used.

But iBATIS dosen't provide ways to execute both select statement and update statement at the same time(as I know), I decided to use stored procedure. Because it is possible to lock the table row in case of server failure right after the first select(for update) statement is executed but before second update statement is excuted.



The stored procedure is like following
CREATE OR REPLACE FUNCTION gen_num_for_table(table_name_in IN VARCHAR2)
  RETURN NUMBER
  IS
  next_no_out NUMBER;
BEGIN
  SELECT next_no INTO next_no_out
  FROM ps_number
  WHERE table_name = table_name_in
  FOR UPDATE WAIT 3;

  UPDATE ps_number SET next_no = next_no + 1
  WHERE table_name = table_name_in;

  RETURN next_no_out;
END gen_num_for_table;


Now, for server applications the SQL Map is like following



The statement part should be enclosed with curly brackets({}) and the statement is proceeded by '? = call' in case of function. In case of procedure, just start with 'call'. These are same syntax with java.sql.CallableStatement. Acually, iBATIS will execute callable statement using specified statement and parameterMap.
The parameterMap should be specified surely. The order of parameter is important. In case of function, the first parameter is for return value and so should have 'OUT' mode attribute. For each parameter, jdbcType should be specified explicitly, so as to be interpreted to CallableStatment.registerOutParameter method with correct parameter and setXXX of CallableStatement.



Finally the application using above sql map is like following

public int generateNumberForTable(String tableName) throws Exception{

  java.util.Map map = new java.util.HashMap();
  map.put("table_name", tableName);

  this.sqlMapClient.queryForObject("Common.generateNumberForTable", map);

  return (Integer)map.get("next_no");
}


The input is given using map object as is expected from SQL Map definition. The important thing is that the result is not given as a return value of queryForObject method but is put in the map with the key specified in SQL Map definition.



For your information, the equivalent codes using plain JDBC would be like following. It could help you understand how the above codes would work.
public int generateNumberForTable(String tableName) throws Exception{
   Connection conn = null;
   CallableStatement cstmt = null;

   try{
      DataSource ds = this.sqlMapClient.getDataSource();
      conn = ds.getConnection();
      cstmt = conn.prepareCall("{? = call gen_num_for_table(?)}");
      cstmt.registerOutParameter(1, java.sql.Types.INTEGER);
      cstmt.setString(2, tableName);

      cstmt.executeQuery();

      return cstmt.getInt(1);
   }catch(Exception ex){
      ex.printStackTrace(System.err);
      throw ex;
   }finally{
      if(cstmt != null){ try{ cstmt.close();}catch(Exception ex2){} }
      if(conn != null){ try{ conn.close();}catch(Exception ex2){} }
   }
}


For more readings.

iBatis and Stored Oracle procedures/functions
This is the article that I found after this writing and I think it gives you more information about iBATIS and Oracle stored procedure/function. I didn't execute personally the code in that article and I didn't understand what is 'ORACLECURSOR' type in the example code, but as a whole you can find hints or guide from the article.



Useful UNIX Commands and Shell Scripts
2008-11-12T11:35:00.034+09:00
Often-used Solaris Commands
Really concise and useful



http://www.themis.com/supp/suppfaqs/faqs_solaris.htm#q36


View files in octal or hexadecimal format - od
You can view non ascii base files in hexadecimal format using od command.

% od -A d -x journal.log


For more about od, refer the following.

   http://www.opengroup.org/onlinepubs/9699919799/utilities/od.html
   http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.cmds/doc/aixcmds4/od.htm



Find files with specified name and list them with full path
If you want to find files with extension of 'jar' and print them with full path, use find command with -exec operator like the following.

% find . -name '*.jar' -exec ls -l {} \;

For more about find command and -exec operator including strange '{}' or '\;' in the above example, refer the followings.

   http://www.opengroup.org/onlinepubs/9699919799/utilities/find.html
   http://docstore.mik.ua/orelly/unix3/upt/ch09_01.htm



Find files containing the specified word



List files using find command excluding files with 'Permission denined'


When executing find command in simplest format, you may get lots of lines just saying that 'Permission denied'. Most cases, those are not what you want, and lots of permission denied lines can disturb you identifying the wanted result.


You can use stderr redirection to cut out permission denied files (or directories).




  How can I exclude all “permission denied”-messages from “find .”? (from stackoverflow)
  Redirection on Wikipedia







Sorting the file system usage result from the du command

You can sort the output of du command applying pipe to sort command.


% du -m | sort -n


For more about du and sort, read the followings.


   du - estimate file space usage
   sort - sort, merge, or sequence check text files



Finding large files


To find large files(not directories) under current directory and list them in pages, use the following command.


% find . -type f -exec du -k {} 2>/dev/null \; | sort -nr | more



To filter out small files, you can use size option with find command, or to filter out some subdirectories you can redirect the result to grep command.

The following command will list files whose size are more than 1 mega-byte under current directory recursively except the subdirectories starting with 'svn' in order of their size.


% find . -type f -size +1000000c -exec du -k {} 2>/dev/null \; | sort -nr | grep -E "\./svn.*" -v




Identifying the shell of your current login

To identify what shell a user is set to use by default, you can check 'SHELL' variable.



As the above example shows, SHELL variable contains the login default shell type not the one currently in use.



Identifying the product of Linux installed

For Linux, /etc/issues file contains more detailed information on what Linux product it is.





Identifying TCP/IP ports currently in use.


You can identify TCP/IP ports currently in use using netstat command. The options of netstat is slightly different among operating systems.



For UNIX,



For Linux,

You need root privilege to take effect of -p option


For Windows,



For more about netstat, refer topics in Wikipedia.



Paginated Query
2008-11-03T09:29:00.022+09:00
The statements to retrieve partial rows from selected data are like followings according to the DBMS.




Oracle (8i or higer)
Use ROW_NUMBER() function and subquery. In some cases, such as hierarchical query (START WITH ~ CONNECT BY ~ clause) using ORDER SIBLINGS BY, ROW_NUMBER() function can't be used in subquery, so in those cases, ROWNUM with double-nested subquery can be used.


Syntax : 
SELECT *
FROM (
   SELECT ROW_NUMBER() OVER (ORDER BY ~) AS row_no, ~
   FROM ~ 
   WHERE ~ )
WHERE row_no BETWEEN m AND n

Example :
select *
from(
  select row_number(order by product_name) as row_no,
      product_id, product_name, price, manufacturer
  from tb_product
  where category_id = 101)
where row_no between 21 and 30



Microsoft SQL Server (2005 or higher)

Syntax : 
WITH ~ AS(
   SELECT ~ , ROW_NUMBER() OVER(~) AS row_no
   FROM ~
   WHERE ~
)
SELECT ~
FROM ~
WHERE row_no BETWEEN m AND n

Example : 
with v_product as (
   select row_number() over(order by product_name) as row_no,
      product_id, product_name, price, manufacturer
   from tb_product
   where category_id = 101)
select *
from v_product
where row_no between 21 and 30



MySQL

Syntax :
SELECT ~ 
FROM ~ 
WHERE ~ 
ORDER BY ~
LIMIT offset, row_count

Example : 
select product_id, product_name, price, manufacturer
from tb_product
where category_id = 101
order by product_name
limit 20, 10


The query with both LIMIT clause and ORDER BY clause sort the result before limit unlike Oracle so, you need not use subquery.


PostgresSQL

Syntax : 
SELECT ~ 
FROM ~ 
WHERE ~ 
ORDER BY ~ 
LIMIT row_count OFFSET offset

Example : 
select product_id, product_name, price, manufacturer
from tb_product
where category_id = 101
order by product_name
limit 10 offset 20


The query with both LIMIT/OFFSET clause and ORDER BY clause sort the result before limit unlike Oracle so, you need not use subquery.


Informix

Syntax : 
SELECT SKIP offset FIRST row_count selection_list
FORM ~
WHERE ~
ORDER BY ~



Readings


  Limiting result rows of SELECT (from Wikipedia)



UNIQUE constraint of Microsoft SQL Server and CHECK constraint of MySQL
2008-09-24T00:53:00.006+09:00
Micsoft SQL Server allows only one null value for the column having UNIQUE constraint, as with any other(non-null) value.  This is quiet different from Oracle.



MySQL provides CHECK contraint syntax in its SQL, but it doesn't really check the contraint in run-time, at leat as of version 5.0. The syntax is for compatibility of the SQL.


Maximum Length of VARCHAR Type in Major DBMS
2008-09-22T15:10:00.012+09:00

Oracle 8 ~ 10g : 4,000 Byte
Microsoft SQL Server : 8,000 Byte (not sure)
MySQL 5.0.3 before : 255 Byte
MySQL 5.0.3 or higher : 65,535 Byte



Default TCP/IP Port of Microsoft SQL Server 2005 Express
2008-09-22T14:47:00.005+09:00
After Install, the default settings for Microsoft SQL Server 2005 Express are different from those which are expected in previous versions.

TCP/IP  is not enabled for the Server
The default TCP port is not 1433 (which is default previous versions)

So, if you would make JDBC connections from your applications, you should setup followings first.

Enable TCP/IP for the serve : 

Load SQL Server Configuration Manager, in SQL Server 2005 Network Configuration/Protocols for SQLEXRPRESS dialog, make enable TCP/IP (SQLEXPRESS is instance name of SQL Server, so is dependent on your installation)

Check the TCP port of your server : 

In above SQL Server 2005 Network Configuration/Protocols for SQLEXRPRESS dialog, double click TCP/IP item. At the loaded dialog, seek into IP Addresses tab, IP All section, and TCP Dynamic Ports and that is TCP port for JDBC connection.

Those may be same with SQL Server 2005.


DbUnit with Oracle
2008-09-11T09:05:00.013+09:00
When using DbUnit with Oracle, the followings are recommened to avoid exceptions or something like that.


Provide the schema name when creating the database connection.
Use the OracleDataTypeFactory.
Disable FEATURE_QUALIFIED_TABLE_NAMES
Enable FEATURE_SKIP_ORACLE_RECYCLEBIN_TABLES


IDatabaseConnection conn = new OracleConnection(ds.getConnection(), "MYSCHEMA");
DatabaseConfig config = conn.getConfig();
config.setFeature(DatabaseConfig.FEATURE_QUALIFIED_TABLE_NAMES, false);
config.setFeature(DatabaseConfig.FEATURE_SKIP_ORACLE_RECYCLEBIN_TABLES, true);
config.setProperty(DatabaseConfig.PROPERTY_DATATYPE_FACTORY, new OracleDataTypeFactory());



Using Keyword with Table Name and DbUnit
2008-08-18T23:13:00.004+09:00
DbUnit 2.2 doesn't support automatic identifier quotation for auto generated DDLs or DMLs.



So, using with MySQL where table name may be keyword like 'order', 'lower-case-table-names' system variable of MySQL should be set to '0' on Unix or '2' on Windows and FEATURE_QUALIFIED_TABLE_NAMES of DbUnit should be set to 'true'.



Note that 'lower-case-table-names' is not dynamic variable, so it should be set at start-up like using my.ini.


Annotation Based JMX in Spring Framework 2.5
2008-08-04T16:22:00.005+09:00
In spring framework 2.5, to use annotation based JMX


The position of the JMX bean definition in bean config
The type of proxy

is important.


Blocking Remote Images in Thunderbird 2
2008-08-04T15:59:00.005+09:00
In Thunderbird 2, the blocking of remote image to protect privacy is active by default. Sometimes this could be annoying.  To change this behavior, you should use "advanced configuration" which is located at "General" tab of "Advanced" section in option dialog.  At that dialog,


Click "Config Edit..." button, then a new dailog would pop up.
Fill in "remote" in "Filter" textbox and you could see "mailnews.message_display.disable_remote_image" preference which is set to true.
Double click the above preference, and it would change to false.

DBMS	Block Comments	Line Comments
Oracle	/* comments text */	-- comments text
DB2		-- comments text
SQL Server (2000+)	/* comments text */	-- comments text
MySQL (4.0+)	/* comments text */	-- comments text # comments text
PostgreSQL	/* comments text */	-- comments text

Case	Base	Prefix	Format	Example
HTML/XML Character Entities	decimal	&#	&#nnnn	&#169 for copyright symbol. &#913 for Greek capital letter alpha.
HTML/XML Character Entities	hexadecimal	&#x	&#xhhhh	&#xA9 for copyright symbol. &#x391 for Greek capital letter alpha.
CSS Colors	hexadecimal	#	#hhhhhh or #hhh	#000000 for black, #ffffff for white, #800080 for purple, #808000 for olive, #ffa400 for orange
Unicode Code Points	hexadecimal	U+	U+hhhh, U+hhhhh or U+hhhhhh
Unicode Escape Sequence for Character and String Literals	hexadecimal	\u	\uhhhh	\u0008 for backspace BS, \u0022 for double quote " \u005c for backslash \
Octal Escape Sequence for Character and String Literals	octal	\	\ooo	\10 for backspace BS, \42 for double quote " \134 for backslash \

View	Description
USER_USERS	Describes only the current user.
ALL_USERS	Lists users visible to the current user, but does not describe them.
USER_TS_QUOTAS	Describes tablespace quotas for current user.
USER_RESOURCE_LIMITS	Displays the resource limits for the current user.
USER_PASSWORD_LIMITS	Describes the password profile parameters that are assigned to the user.

View	Description
DBA_USERS	Describes all users of the database.
DBA_TS_QUOTAS	Describes tablespace quotas for users.
DBA_PROFILES	Displays all profiles and their limits.
V$SESSION	Lists session information for each current session, includes user name.

XSLT Processor	Value
Xalan	`org.apache.xalan.processor.TransformerFactoryImpl`
Xalan bundled in JDK 1.5	`com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl`
Xalan XSLTC	`org.apache.xalan.xsltc.trax.TransformerFactoryImpl`
Saxon 6.x	`com.icl.saxon.TransformerFactoryImpl`
Saxon 7.x and 8.x:	`net.sf.saxon.TransformerFactoryImpl`

Plug-in	Site	Description
SpringSource Tool Suite	http://www.springsource.com/developer/sts	Spring framework development tools
Hibernate Tools for Eclipse and Ant	http://www.hibernate.org/subprojects/tools.html	Hibernate development tools
AJDT	http://www.eclipse.org/ajdt/	AspectJ development tools
Google Plugin for Eclipse	http://code.google.com/appengine/docs/java/tools/eclipse.html	development tools for GWT and Google App Engine
Vex	http://marketplace.eclipse.org/content/vex/click	visual editor for XML
Mylyn WikiText	http://wiki.eclipse.org/Mylyn/WikiText	tools for parsing, editing and presenting lightweight markup
m2eclipse	http://eclipse.org/m2e/	Maven plug-in
Subclipse	http://subclipse.tigris.org/	Subversion client
DBViewer Plugin	http://www.ne.jp/asahi/zigen/home/plugin/dbviewer/	General database client
jOra	http://jora.luenasoft.de/	Oracle database client
JadClipse	http://sourceforge.net/projects/jadclipse/	Java decompiler
LogViewer	http://code.google.com/a/eclipselabs.org/p/logviewer/	File viewer
Properties Editor	http://propedit.sourceforge.jp/index_en.html	File editor
JDepend4Eclipse	http://andrei.gmxhome.de/jdepend4eclipse/	Code analysis
Regex Util	http://myregexp.com/eclipsePlugin.html	testing/editing regular expressions flavor of the Sun Java standard API (java.util.regex)
Eclipse Hex Editor Plugin (EHEP)	http://ehep.sourceforge.net/	File editor allows user to view or modify any file in hex mode.
Eclipse launcher for VisualVM	http://visualvm.java.net/eclipse-launcher.html	monitoring and profiling Eclipse projects using VisualVM

Binding	Command	When	Description
`F5`	Refresh	In Windows	Refresh the selected items
`Ctrl + Space`	Content Assist	In Dialogs and Windows	Popup to provide contextual proposals
`Ctrl + I`	Indent Line	Editing Java Source	Adjust indentations of lines in selected block
`Ctrl + L`	Go to Line	Editing Text	Go to a specified line of text
`Ctrl + G`	Declaration in Workspace	Editing in Structured Text Editors	Search for declarations of the selected element in the workspace
`Ctrl + /`	Toggle Comment	Editing SQL, Editing Properties Files, Editing JavaScript Source, Editing Java Source	Toggle comment the selected lines
`Ctrl + Shift + F`	Format	Editing in Structured Text Editors	Format selection
`Ctrl + Shift + G`	References in Workspace	In Windows	Search for references to the selected element in the workspace
`Ctrl + Shift + M`	Add Import	Editing Java Source	Create import statement on selection
`Ctrl + Shift + R`	Open Resource	In Windows	Open an editor on a particular resource
`Alt + Shift + J`	Add Javadoc Comment	In Windows	Add a Javadoc comment stub to the member element
`Alt + Left`	Backward History	In Windows	Activate previous resource in editor history.
`Alt + Right`	Forward History	In Windows	Activate next resource in editor history.

Item	HSQLDB (1.8)	H2(1.1.109)	SQLite (3.6.22)
Lanaguage	Java	Java	C
Supports Client/Server Mode	Yes	Yes	No
Supports Embedded Mode	Yes	Yes	Yes
Supports In-Memory Databases	Yes	Yes	Yes
Provided Transaction Isolation Mode	Read Uncommitted	Read Committed, Serializable	Unclear
Supports Foreign Key Constraint	Yes	Yes	Yes (≥ 3.6.19)
Supports View Object	Yes	Yes	Yes
Supports Sequence Object	Yes	Yes	No
Supports User-defined Procedure/Function	Yes	No	No
Supports Trigger	Yes	Yes	Yes
Supports Inner Join	Yes	Yes	Yes
Supports Left Outer Join	Yes	Yes	Yes
Supports Right Outer Join	Yes	Yes	No
Supports Full Outer Join	Yes	Yes	No
Supports ORDER BY Clause	Yes	Yes	Yes
Supports GROUP BY/HAVING Clause	Yes	Yes	Yes
Supports Paginated Query	Yes (offet m fetch n lows)	Yes (limit n offset m)	Yes (limit n offset m)
Provides C API	No	No	Yes
Provides JDBC Driver	Yes	Yes	by 3rd party
Provides ODBC Driver	under development	Yes	No
Explicitly Supported by Hibernate 3.3	Yes	Yes	No
Explicitly Supported by DbUnit 2.4	Yes	Yes	No
Explicitly Supported by Power*Architect 0.9.13-RC1	Yes	No	No

Thirdstage's Blog

Exception Handling of EJB

EJB 2.1

Exceptions from a Session or Entity Bean’s Business Methods

EJB 3.0

Exceptions from a Session Bean’s Business Interface Methods

Using SyntaxHighlighter in Redmine

Guildelines for Multi-moduled Maven Project

Guildelines for Multi-moduled Maven Project

Separate parent project from container project.

Define properties in the parent POM file as possible.

Define the following properties explicitly for clearness and control.

Define all plugins in the <pluginManagement> element of parent POM file.

Define repositories in the parent POM file as possible.

Define plugins to analyze or diagnose the sources or resources of the project as a reporting plugin as possible.

Start values for path with ${project.basedir}, ${project.build.directory}, ${project.build.outputDirectory} or so on

Use resources in target/classes not in src/main/resources, considering resource filtering.

Sample of Parent POM

Frameworks, Libraries, Tools, and Utilities

Frameworks

Logging

Templating

HTML/CSS

Libraries

JavaScript

Expression Language

Tools

Java Source Analysis

Java Performance Monitoring

Java Dump Analysis

Web Development

SQL Client/Database Management

ETL

Utilities

PC Diagnostic and Recovery

File Synchronization

Readings on Business Applications

Data-warehouse, BI

Tips on Regex

Readings : References, Tutorials and Articles

Special Characters of ERE (Extended Regular Expression)

Regex with Java

Formal rules for bracket expression

Capturing, Grouping and Backreferences

NOT operator in Regex

Nested pairs search

Lookaround : lookahead and lookbehind

Greedy, Reluctant, or Possessive Quantifiers

Servlet, JSP, JSTL, JSF and EL Compatibility

Servlet and JSP Versions

JSTL Compatibility

JSF Compatibility

EL Compatibility

References

My Styles

Styles for Redmine of my team

Access InitialContext by Application Server

Readings

JBoss

WebLogic

Investgating InitialContext

Concurrency and Transaction in Oracle

Locks Obtained by DML Statements in Oracle

Locking for SELECT statement

Locking for INSERT, UPDATE, DELETE, and SELECT ... FOR UPDATE statement

Tips on MyBatis

Thread-safety of SqlSession

General method to check properties of an object using Spring EL

Simple Code Patterns in Java

Typical code pattern for Regex API

Lazy initialization of field

Lazy initialization of instance field using double-checked locking

Lazy initialization of static field using initialization on demand holder class

More readings

More codes

CommonAnnotationBeanPostProcessor.findResourceMetadata method of Spring framework

Tips on Spring

Readings : References, Tutorials, Articles

Schemas for XML based configuration

Configuring Dependency in Maven to Use Auto-detecting and Name-based Auto-wiring of Beans with Spring 3.0

Define all plugins in the `<pluginManagement>` element of parent POM file.

Start values for path with `${project.basedir}`, `${project.build.directory}`, `${project.build.outputDirectory}` or so on

Use resources in `target/classes` not in `src/main/resources`, considering resource filtering.

Locking for `SELECT` statement

Locking for `INSERT, UPDATE, DELETE`, and `SELECT ... FOR UPDATE` statement

Thread-safety of `SqlSession`

`CommonAnnotationBeanPostProcessor.findResourceMetadata` method of Spring framework