Simplify XML processing with VTD-XML

Summary
As the enabling technology for next-generation Web-based applications, XML is both easy and straightforward to learn and use. Unfortunately, the same thing cannot be said about the current state of XML processing: the Document Object Model and the Simple API for XML are both too slow, inefficient, and difficult to use. Providing a broadly useful and advanced option that goes beyond DOM and SAX, VTD-XML is the next-generation XML processing model that simplifies both XML programming and selection of an XML processing model. By highlighting some of the key technical strengths of VTD-XML using the latest performance benchmark numbers and code examples, this article demonstrates that VTD-XML has the potential to finally take the "monkey" off the back of enterprise architects constantly struggling with the decision of whether to use DOM or SAX.

http://www.javaworld.com/javaworld/jw-03-2006/jw-0327-simplify.html

Log4j example

**here has four examples about how to utilize log4j.

the core of log4j is log4j.properties, we can do some configuration in this property files, including log message format, output file name, appender

setting and so on.

1. com.ptc.demo.log4j.module1.Module1Test: write log information to console
2. com.ptc.demo.log4j.module2.Module2Test: write log information to log files and rotate the log file by day
3. com.ptc.demo.log4j.module3.Module3Test: write log information to log files and rotate the log file by file size
4. com.ptc.demo.log4j.module4.Module4Test: write log information to log file (in HTML format)


---------------------
output message
---------------------
2006-03-24 13:50:03,015 DEBUG com.ptc.demo.log4j.module1.Module1Test.sortByAsc(Module1Test.java:26) - [ant, cat, dog, dophin, tiger, zebra]
2006-03-24 13:50:03,015 DEBUG com.ptc.demo.log4j.module1.Module1Test.sortByDesc(Module1Test.java:41) - [zebra, tiger, dophin, dog, cat, ant]



log4j.properties
=========================================================================
#module1 -- output to console
log4j.category.com.ptc.demo.log4j.module1=DEBUG,module1
log4j.appender.module1=org.apache.log4j.ConsoleAppender
log4j.appender.module1.layout=org.apache.log4j.PatternLayout
log4j.appender.module1.layout.ConversionPattern=%d %5p %l - %m%n


#module2 -- output to log and rotate by day
log4j.category.com.ptc.demo.log4j.module2=DEBUG,module2
log4j.appender.module2=org.apache.log4j.DailyRollingFileAppender
log4j.appender.module2.threshold=debug
log4j.appender.module2.File=C:\module2.log
log4j.appender.module2.DatePattern='.'yyyyMMdd
log4j.appender.module2.Append=true
log4j.appender.module2.layout=org.apache.log4j.PatternLayout
log4j.appender.module2.layout.ConversionPattern=%d %5p %l - %m%n


#module3 -- output to log and rotate by file size
log4j.category.com.ptc.demo.log4j.module3=DEBUG,module3
log4j.appender.module3=org.apache.log4j.RollingFileAppender
log4j.appender.module3.threshold=debug
log4j.appender.module3.File=C:\module3.log
#rotate size = 500 KB
log4j.appender.module3.MaxFileSize=500KB
#keep three backup files
log4j.appender.module3.MaxBackupIndex=3
log4j.appender.module3.layout=org.apache.log4j.PatternLayout
log4j.appender.module3.layout.ConversionPattern=%d %5p %l - %m%n


#module4 -- output to log and by HTML format
log4j.category.com.ptc.demo.log4j.module4=DEBUG,module4
log4j.appender.module4=org.apache.log4j.FileAppender
log4j.appender.module4.File=C:\module4.html
log4j.appender.module4.Append=true
log4j.appender.module4.layout=org.apache.log4j.HTMLLayout
=========================================================================


class file (each class file has the same content and only has different class name)
=========================================================================
package com.ptc.demo.log4j.module1;

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.Collections;

import org.apache.log4j.Logger;

/**
*
* @author Albert
*
*/
public class Module1Test {

private static Logger logger = Logger.getLogger(Module1Test.class.getName());

/**
* sorting by ascending
* @param str
*/
public void sortByAsc(String str[]){
List list = Arrays.asList(str);
Collections.sort(list);
logger.debug(list);
}

/**
* sorting by descending
* @param str
*/
public void sortByDesc(String str[]){
List list = Arrays.asList(str);
Collections.sort(list, new Comparator(){
public int compare(Object obj1, Object obj2){
return ((String)obj2).compareTo((String)obj1);
}
}
);
logger.debug(list);
}

/**
* @param args
*/
public static void main(String[] args) {
Module1Test module1Test = new Module1Test();

String str[] = new String[]{"dog","ant","zebra","cat","tiger","dophin"};
module1Test.sortByAsc(str);
module1Test.sortByDesc(str);
}

}
=========================================================================

Exception Handling

The following are some of the generally accepted principles of exception handling:

1. If you can’t handle an exception, don’t catch it.
2. If you catch an exception, don’t swallow it.
3. Catch an exception as close as possible to its source.
4. Log an exception where you catch it, unless you plan to rethrow it.
5. Structure your methods according to how fine-grained your exception handling must be.
6. Use as many typed exceptions as you need, particularly for application exceptions.


"Best Practices in EJB Exception Handling"
http://www-106.ibm.com/developerworks/java/library/j-ejbexcept.html

"Best Practices for Exception Handling"
http://www.onjava.com/pub/a/onjava/2003/11/19/exceptions.html

"Designing with Exceptions"
http://www.javaworld.com/jw-07-1998/jw-07-techniques.html

"Exceptions in Java"
http://www.javaworld.com/jw-07-1998/jw-07-exceptions.html

"Exceptional Practices, Part 1"
http://www.javaworld.com/javaworld/jw-08-2001/jw-0803-exceptions.html

"Exceptional Practices, Part 2"
http://www.javaworld.com/javaworld/jw-09-2001/jw-0914-exceptions.html

"When catching exceptions, don't cast your net too wide"
http://www.javaworld.com/javaworld/javatips/jw-javatip134.html

"Use nested exceptions"
http://www.javaworld.com/javaworld/javatips/jw-javatip91.html

"Beware the dangers of generic exceptions"
http://www.javaworld.com/javaworld/jw-10-2003/jw-1003-generics.html

[Info] Abator: code generator for iBATIS

Abator is a code generator for iBATIS. Abator will introspect a database table (or many tables) and will generate iBATIS artifacts that can be used to access the table(s). This lessens the initial nuisance of setting up objects and configuration files to interact with database tables. Abator seeks to make a major impact on the large percentage of database operations that are simple CRUD (Create, Retrieve, Update, Delete). You will still need to hand code SQL and objects for custom queries, or stored procedures.


http://ibatis.apache.org/abator.html

Plug memory leaks in enterprise Java applications

Strategies for detecting and fixing enterprise memory leaks

Summary
Because Java uses automatic garbage collection, developers think Java programs are free from possible memory leaks. Although automatic garbage collection solves the main cause of memory leaks, they can remain in a Java program. Specifically, such memory leaks in complex multitiered applications can be extremely daunting to detect and plug. This article analyzes the main causes of memory leaks in Java Enterprise Edition (Java EE) applications, and suggests strategies for detecting them. (3,200 words; March 13, 2006)

By Ambily Pankajakshan

http://www.javaworld.com/javaworld/jw-03-2006/jw-0313-leak.html

[Info] Tons of Java opensources

http://java-source.net/open-source

[Troubleshooting] The deployment framework was unable to register with the Data Replication Service

Description
Deployer:149204]The deployment framework was unable to register with the Data Replication Service.


Resolution
確認一下，在/etc/hosts裡頭是否有127.0.0.1 localhost
若無，請加上127.0.0.1 localhost
並且需重開機才能生效

[Troubleshooting] MailSendException: Could not send mails: 501 illegal character(s) in domain string

[Scenario]
As I wrote a Java code, and used JavaMail to send email. But it threw this kind of exception message:
org.springframework.mail.MailSendException: Could not send mails: 501 : illegal character(s) in domain string

[Solution]
Because the computer's host name is Big5, so it will throw this kind of exception. This problem had been resolved, as I change my host name to English, and restart my computer.

[Info] MaxPermSize and how it relates to the overall heap

MaxPermSize and how it relates to the overall heap

Many people have asked if the MaxPermSize value is a part of the overall -Xmx heap setting or additional to it. There is a GC document on the Sun website which is causing some confusion due to a somewhat vague explanation and an errant diagram. The more I look at this document, the more I think the original author has made a subtle mistake in describing -Xmx as it relates to the PermSize and MaxPermSize.

First, a quick definition of the "permanent generation".

"The permanent generation is used to hold reflective data of the VM itself such as class objects and method objects. These reflective objects are allocated directly into the permanent generation, and it is sized independently from the other generations." [ref]



Yes, PermSize is additional to the -Xmx value set by the user on the JVM options. But MaxPermSize allows for the JVM to be able to grow the PermSize to the amount specified. Initially when the VM is loaded, the MaxPermSize will still be the default value (32mb for -client and 64mb for -server) but will not actually take up that amount until it is needed. On the other hand, if you were to set BOTH PermSize and MaxPermSize to 256mb, you would notice that the overall heap has increased by 256mb additional to the -Xmx setting.

So for example, if you set your -Xmx to 256m and your -MaxPermSize to 256m, you could check with the Solaris 'pmap' command how much memory the resulting process is taking up.

i.e.,

$ uname -a
SunOS devnull 5.8 Generic_108528-27 sun4u sparc
SUNW,UltraSPARC-IIi-cEngine

$ java -version
java version "1.3.1_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1_02-b02)
Java HotSpot(TM) Client VM (build 1.3.1_02-b02, mixed mode)

---------------------------------------------
$ java -Xms256m -Xmx256m -XX:MaxPermSize=256m Hello &
$ pmap 6432
6432: /usr/java1.3.1/bin/../bin/sparc/native_threads/java -Xms256m -Xmx256m

total 288416K
---------------------------------------------
Notice above that the overall heap is not 256m+256m yet? Why? We did not specify PermSize yet, only MaxPermSize.


---------------------------------------------
$ java -Xms256m -Xmx256m -XX:PermSize=256m -XX:MaxPermSize=256m Hello &
$ pmap 6472
6472: /usr/java1.3.1/bin/../bin/sparc/native_threads/java -Xms256m -Xmx256m

total 550544K
---------------------------------------------

Now we see the overall heap grow, -Xmx+PermSize. This shows conclusive proof that PermSize and MaxPermSize are additional to the -Xmx setting.


Link

[Troubleshooting] Managed Server cannot boot after password of admin user has been changed from admin console

DESCRIPTION:
If you change the password of the admin user from the admin console without running managed servers, the managed servers cannnot boot because of an authentication error of the admin user.

Resolution:
Security data e.g., password) is stored in the Embedded LDAP by default and it is replicated from the admin server to the managed servers. If there is an inconsistency of the security data between the admin and managed servers, the error will occur.
In order to refresh all replicated data at boot time, you need to set 'Refresh Replica At Startup' from the Admin Console. You can set this property by following the following steps in the Admin console:
Domain --> Security --> Embedded LDAP Server.

[Info] Spring PropertyPlaceholderConfigurer

How many times have you been on a project, and people are talking about where to share configuration data?

Do I use some constants? What about a config file (XML, properties, etc)?

Sometimes it isn't easy to know what to do, and you sometimes end up with duplicate information.

For example, what if you want to share database information between your code, your ant build, and anything else?

With Spring, you can use their really nice PropertyPlaceholderConfigurer, and easily share a properties file. You can simply share one properties file for all of your build info as well as Spring sharing, or you can of course seperate things out, and have multiple 's in your build script.

So, the steps for sharing the data:......

http://www.almaer.com/blog/archives/000449.html

[novelty] lipstick indicator & Lipstick Theory

lipstick indicator
An indicator based on the theory that a consumer turns to less-expensive indulgences, such as lipstick, when she (or he) feels less than confident about the future. Therefore, lipstick sales tend to increase during times of economic uncertainty or a recession.


Lipstick Theory
This theory is also applied in medical industry.
"The Lipstick Theory: When a woman who is battling cancer starts to put on lipstick, she is on the road to recovery."
- William Cahan, M.D., Memorial Sloan Kettering Cancer Center

Is Ajax gonna kill the web frameworks?

The Java eco system has zillions of web frameworks from JSF, Tapestry, Struts, WebWork, Spring WebFlow to things like JSP/JSTL/Velocity etc. There's probably a new web framework born every day in Java some place.

However if the world really does go Ajax or some kinda client technology very Ajax like - will that cause these traditional HTML/HTTP web frameworks to become legacy?

Web frameworks spend most of their time doing things like, dealing with HTTP and HTML, maintaining client side state on the server - handing intermediate form submissions & validation, templating/rendering issues and binding business objects to HTML form controls etc.

These days Ajax has template engines, XPath/XSLT engines, SOAP stacks, XForms implementations and so forth all done on the client side. You can do clever things like hide the JavaScript from your HTML page and use CSS to bind the JavaScript to the markup.

There's even a JavaScript version of Ruby on Rails that runs in the browser! :)

So is the web application of the future going to be static HTML & JavaScript, served up by Apache with Ajax interacting with a bunch of XML based web services (maybe using SOAP, maybe just REST etc)? If so, do we really need a web framework thats focussed on HTTP and HTML, or are we just gonna end up developing a bunch of XML based web services and letting Ajax do all the templating, editing and viewing?

Is this the end of web frameworks as we know it?

http://radio.weblogs.com/0112098/2005/11/16.html

[Info] Linux 常用指令

殺光folder下所有檔案
rm -rf

解開tar檔到特定folder下
tar xvf project.tar -C

看目前的process
ps -ef

重開機
init 6

檢視Log
tail -f

解開gz檔
tar -zxvf jrockit-70sp5-j2se131-linux32.tar.gz

[Troubleshooting] java.lang.SecurityException: Unable to locate a login configuration

Environment
RedHet Enterprise Linux 2.1
WLS 6.1
Service Pack 7
JRocket 1.4

Problem
As I would like to startup weblogic, it will show this kind of error message
java.lang.SecurityException: Unable to locate a login configuration
at com.ibm.security.auth.login.ConfigFile.getAppConfigurationEntry(ConfigFile.java:221)
at javax.security.auth.login.LoginContext.init(LoginContext.java:171)
at javax.security.auth.login.LoginContext.(LoginContext.java:318)
at weblogic.security.internal.ServerAuthenticate.main(ServerAuthenticate.java:81)
at weblogic.t3.srvr.T3Srvr.run(T3Srvr.java:200)
at weblogic.Server.main(Server.java:35)

Solution
You can check this file http://www.genuitec.com/products/JDK14_WLS61.pdf
Owing to the certified JDK version in WLS 6.1 is 1.3, the JDK version is 1.4

[Info] Java Performance Tuning

http://www.javaperformancetuning.com/

[Info] WebLogic Server End-of-Life Calendar

You can check this link to ensure your product's status:
WebLogic Server End-of-Life Calendar


If it was retired, BEA do not provide technical support any more.

[Info] Hardware Capacity Management How-To

When you examine performance, a number of factors influence how much capacity a given hardware configuration will need in order to support WebLogic Server and a given application. The hardware capacity required to support your application depends on the specifics of the application and configuration. You should consider how each factor applies to your configuration and application.

Before continuing with this section, you may want to review the Standard Performance Evaluation Corporation which provides a set of standardized benchmarks and metrics for evaluating computer system performance.

[Troubleshooting] Apache HTTP Server cannot start

[Scenario]
有些時候，可能因為改了某些設定，如修改httpd.conf之後無法正常啟動

[Solution]
此時你可以執行Test Configuration來看錯誤訊息
開始→程式集→Apache HTTP Server→Configure Apache Server→Test Configuration

[Info] Struts+Spring+iBatis的輕量級J2EE開發

Struts+Spring+iBatis的輕量級J2EE開發