Posts Tagged 'framework'

Apache Log4j

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Category: Framework

Published on Friday, 03 September 2004 00:00

Written by Administrator

Hits: 32006

Log4J: A logging framework for J2EE

Log4j homepage: http://jakarta.apache.org/log4j/

Reference book on log4j:

The Complete Log4j Manual by Ceki Gulcu Edition: Paperback

Introduction
Log4j is an open source tool (OSS) developed for inserting logs statements into your application and was developed by people at Apache fundation. It's speed and flexibility allows log statements to remain in shipped code while giving the user the ability to enable logging at runtime without modifying any of the application binary. All of this while not incurring a high performance cost/loss.

Requirements

• Log4j need at least a compatible JDK 1.1.x to run.
• The DOMConfigurator is based on the DOM Level 1 API. The DOMConfigurator.configure(Element) method will work with any XML parser that will pass it a DOM tree. The DOMConfigurator.configure(String filename) method and its variants require a JAXP compatible XML parser, for example Xerces or Sun's parser. Compiling the DOMConfigurator requires the presence of a JAXP parser in the classpath.
• The org.apache.log4j.net.SMTPAppender relies on the JavaMail API. It has been tested with JavaMail API version 1.2. The JavaMail API requires the JavaBeans Activation Framework package.
• The org.apache.log4j.net.JMSAppender requires the presence of the JMS API as well as JNDI.
• Log4j test code relies on the JUnit testing framework in order to maintain quality of release.

Why inserting log statement or rely on this (old) technology?

Why choosing Log4J? (From apache.org)

• log4j is optimized for speed. The system write has been rewrite for efficiency and is now asynchrone (compare to System.err)
• log4j is based on a named logger hierarchy. (category)
• log4j is fail-stop but not reliable.
• log4j is thread-safe. No interblocking thread, or memory leaks.
• log4j is not restricted to a predefined set of facilities.
• Logging behavior can be set at runtime using a configuration file. Configuration files can be property files or in XML format.
• log4j is designed to handle Java Exceptions from the start.
• log4j can direct its output to a file, the console, an java.io.OutputStream, java.io.Writer, a remote server using TCP, a remote Unix Syslog daemon, to a remote listener using JMS, to the NT EventLog or even send e-mail. (Appenders)
• log4j uses 5 levels, namely DEBUG, INFO, WARN, ERROR and FATAL.
• The format of the log output can be easily changed by extending the Layout class.
• The target of the log output as well as the writing strategy can be altered by implementations of the Appender interface.
• log4j supports multiple output appenders per logger
• log4j supports internationalization.
• It is used extensively by thousands of Java developers. If a flaw is discovered it gets fixed in the next release.
• The log4j code is likely to be better than code you'd write yourself and is l ikely to improve over time.
• Ports to other languages are: C++, Eifel, Perl, .NET, Python, Ruby…more than 57 languages are supported

Log4j concepts

Using Log4j in your code

It is not recommended to use log4j api directly, since who knows if a better logging framework won't do better in the future or if log4j won't modify its api's. The main idea is that when you aquire a 3rd party component, is to build a wrapper around it. It is even better if the wrapper contains an abstract factory: maybe in some case you wil have to use different class of logging (because of performance, licence...)

Log4j Guidelines
The FAQ of log4J is a must to read, here are the most important points:

1. Respect Levels!
   Respect levels and categorize the logs according to severity and messages size. Please define a special logger (restricted to a package) that can be switch off and that do not write to much statement in log output.
2. Meaningful statements
   Create code with System.err.println or System.out.println If you are doing some internal reviews of your code, please try to write some meaningful information in logs. Avoid log of type: "I am here", "here 1", "here 2" and so on..
3. Classwide static logger
   It is recommended to provide a class wide logger access point, if you need to do a lot of output in a class or hierarchy. Define a protected Logger in the parent hierarchie
   

   public class Mamals { protected static LoggerWrapper logger = LogFactory.getLog(Mamals.class); ... }

   and use it in all children

   public class Human extends Mamals { public Human() { super(); logger.debug("init"); } }

4. Increase speed
   Log4J is not slow, it is even faster than System.out or System.err (System.err or System.out are synchronous while NOT with log4j, the cost in times comes more from costs during formating messages!
   If you know that you must heavily formatted the output message, do not use the following:
   

   l.debug("Cash balance is " + cashvalue);

   use instead

   if(myLogger.isDebugEnabled()) { myLogger.debug("Cash balance is " + cashBalance.toXML()); }

5. How to name Loggers?
   You can name loggers by locality. It turns out that instantiating a logger in each class, with the logger name equal to the fully-qualified name of the class, is a useful and straightforward approach of defining loggers. This approach has many benefits:

• It is very simple to implement.
• It is very simple to explain to new developers.
• It automatically mirrors your application's own modular design.
• It can be further refined at will.
• Printing the logger automatically gives information on the locality of the log statement.

However, this is not the only way for naming loggers. A common alternative is to name loggers by functional areas. For example, the "database" logger, "RMI" logger, "security" logger, or the "XML" logger. You are totally free in choosing the names of your loggers. The log4j package merely allows you to manage your names in a hierarchy. However, it is your responsibility to define this hierarchy. Note by naming loggers by locality one tends to name things by functionality, since in most cases the locality relates closely to functionality.

Remote logging over TCP
Read carefully: http://jakarta.apache.org/log4j/docs/api/org/apache/log4j/net/SocketAppender.html and
http://jakarta.apache.org/log4j/docs/api/org/apache/log4j/net/SocketHubAppender.html

Starting the server .Chainsaw
Chainsaw is a graphical logging client, where you can see, sort and filter logs data.
Documentation can be read here: http://jakarta.apache.org/log4j/docs/api/org/apache/log4j/chainsaw/package-summary.html and it is a part of log4j.jar

1. Log4 gives you the ability to send messages to a remote location over a socket for logging purposes. The org.apache.log4j.net.SocketAppender and org.apache.log4j.net.SocketServer classes are the key classes used in remote logging.
2. Modify all logger in your log4j.xml to use a SocketApender as appender, Once you have loaded this configuration, all messages will be written to the machine and port that you specify.
3. Start the client application (Chainsaw), this program will receive logs and show them in a swing GUI

On the server side (where your application create logs), you will need to run log4j's SocketServer class. You can create a configuration file with configuration information similar to the following: The whole applcation is in DEBUG mode

1. Set up your CLASSPATH on both the client and server to contain log4j.jar
2. Run the SocketServer at the command line. The command line syntax for the SocketServer is as follows:
   java org.apache.log4j.net.SocketServer portNumber configurationFile configurationDirectory
   start the server:

Start your application, without doing any change in your code or recompiling it, you can now log data remotely!

Configuring log4j

Location of configuration file
The configuration files of log4j must be in classpath, if more than one are in classpath, the first found will be used. Log4j require to have a compatible parser in classpath in order to read the configuration file. As default, Logj use Crimson.jar

Location of DTD
The DTD is needed in order to initialize log4j, 2 solutions are available:

Extending log4j

Defining your application specific loggers, appenders and layouts
You can look at the Log4j API to see how to implement a logger, appender and layout.

Conclusions

One of the strength of log4j is that is do not require to recompile the java code to binary classes to change considerably the ouput amount in logs. You can add logging statements in your code, and without changing the code shipped, change at runtime the amount of log output. Thus the major behaviour logging strategies are done in this file (it can be a properties file or a XML file). You should store this file in the classpath of your application.

Annexes

Example of configuration files:

Resources

• Join the Eclipse Platform community and download the Platform at eclipse.org. The Eclipse Platform source code is licensed under the Common Public License. At eclipse.org, you'll also find a glossary of terms and descriptions of Eclipse projects, along with technical articles and newsgroups. The Eclipse Platform white paper details the major components and functions of Eclipse.
• http://jakarta.apache.org/log4j/ Homepage:
• http://jakarta.apache.org/log4j/docs/api/index.html JAVADOC:
• http://jakarta.apache.org/log4j/docs/FAQ.html FAQ:
• http://www.onjava.com/pub/a/onjava/2002/08/07/log4j.html?page=1 Tutorials
• http://jakarta.apache.org/log4j/docs/api/org/apache/log4j/performance/Logging.html Read the following, it show difference of speed among appenders and layout, Performance of logging when logging is turned on is determined by the cost of walking the logger hierarchy. Typical cost of a hierarchy walk is in the range 5 to 15 microseconds. Actual logging is in order of 100 to 300 micro-seconds.
  

Apache Maven Cargo deploy with Tomcat 7

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Category: Apache Maven

Published on Friday, 27 May 2011 20:33

Written by Administrator

Hits: 3677

Following the post about Deploy to Tomcat 6 using Maven, here is a ready to use example with the main differences explained in the table below

And finally a snippet of an Apache Maven pom.xml ready to use in a profile, so you can reuse this profile like a method call

<profile>
 <id>deployTomcat</id>
<activation>
  <activeByDefault>false</activeByDefault>
</activation>
<build>
 <plugins>
    <plugin>
     <groupId>org.codehaus.cargo</groupId>
     <artifactId>cargo-maven2-plugin</artifactId>
     <version>1.1.0</version>
    <configuration>
     <wait>true</wait>
     <container>
      <containerId>tomcat7x</containerId>
      <type>remote</type>
     </container>
     <configuration>
      <type>runtime</type>
      <properties>
       <cargo.remote.uri>
         ${tomcat.url}
       </cargo.remote.uri>
       <cargo.remote.username>
          ${tomcat.user}     
       </cargo.remote.username>
        <cargo.remote.password>
          ${tomcat.pwd}
        </cargo.remote.password>
      </properties>
      </configuration>
      <deployer>
       <type>remote</type>
       <deployables>
       <deployable>
        <groupId>${deploy.groupid}</groupId>
        <artifactId>${deploy.artifactid}</artifactId>
        <type>war</type>
        <properties>
         <context>${deploy.context}</context>
        </properties>
       </deployable>
      </deployables>
     </deployer>
    </configuration>
    <executions>
     <execution>
      <id>verify-deploy</id>
      <phase>pre-integration-test</phase>
      <goals>
       <goal>deployer-undeploy</goal>
       <goal>deployer-deploy</goal>
      </goals>
     </execution>
    </executions>
    </plugin>
 </plugins>
</build>
</profile>

Place as many profiles as you have machine to deploy in settings.xml and declare some variables as properties, as shown below:

<profile>
 <id>serverA</id>
 <activation>
    <activeByDefault>false</activeByDefault>
 </activation>
 <properties>
    <tomcat.url>http://host.com/manager/text</tomcat.url>
    <tomcat.user>admin</tomcat.user>
    <tomcat.pwd>admin</tomcat.pwd>
    <!-- these properties must be defined
       as system property or -D -->
    <!-- - deployable.artifactid:
         artifactId of web application to be deployed -->
    <!-- - deployable.context: web context name -->
 </properties>
</profile>

So you can run, and traget multiple host by just exchanging the name of the profile serverA to something else.

mvn integration-test –PdeployTomcat,serverA
   –Ddeployable.artifactid=demo
   -Ddeploy.groupid=com.mycompany
   –Ddeployable.context=showcase

new KDE project: PHONON

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Category: Latest

Published on Saturday, 29 April 2006 00:00

Written by Administrator

Hits: 6249

Apache Maven profiles order in multi modules projects

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Category: Apache Maven

Published on Saturday, 07 August 2010 17:27

Written by Administrator

Hits: 9792

In which order are Apache Maven profiles executed? are Apache Maven profiles ordered? how can you insured that Apache Maven profiles are activated in the right order?

You normally don’t end up with these questions, issues may only appear if

• Some profiles are dependent each other,
• Some profiles can not run in any order,

The use case behind this article is very simple, as I have a a continuous build were:

• 5 web applications have  to be deployed into a remote tomcat in phase pre-integration-test,
• 2 databases are created for test cases in phase generate-test-resources
• 1 more database is created and needed for runtime, done in phase pre-integration-test
• One of these web applications is able to inject data into database using web services, a profile do this in a profile in phase pre-integration-test
• Selenium test cases are run in phase integration-test

All these steps are done using several Apache Maven pom profiles.

As it is a bit complicated to explain, lets first refresh some Apache Maven concepts

Read more: Apache Maven profiles order in multi modules projects

Apache Maven Archetype for Joomla

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Category: Joomla

Published on Friday, 17 August 2012 09:22

Written by Administrator

Hits: 930

Got this email from Cyprian Sniegota, he did develop a Maven Archetype for easing development of Joomla extensions. His archetype currently support the creation of a skeleton for components, modules, plugins and templates.

I noticed some time ago that you described combination of Joomla! and Maven. Few weeks ago i wrote joomla-maven-plugin with skeleton projects (sources: bitbucket.org/deviapps) based on php-maven.org work.
Here is short description http://deviapps.com/create-joomla-extension-with-maven and 5 min video (in Polish so far) http://www.youtube.com/watch?v=aE8w9EZciTg
I hope you will be interested.

Thanks to him for having written this project. I will also try to Maven-ize what Joomla has done with Ant in the future (I prefer now crystal clear software lifecycle )

When using Maven jetty:run, CSS and JavaScript files are never updated

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Category: Apache Maven

Published on Monday, 31 May 2010 18:08

Written by Administrator

Hits: 7986

I was getting mad because jetty was refusing to redeploy my static files (xhtml, css) in Eclipse until I find the reason

The Jetty Web Server provides a HTTP server and Servlet container capable of serving static and dynamic contend either from a standalone or embedded instantiations.

Jetty buffers static content for webapps such as html files, css files, images etc and uses memory mapped files to do this if the NIO connectors are being used. The problem is that on Windows, memory mapping a file causes the file to be locked, so that the file cannot be updated or replaced. This means that effectively you have to stop Jetty in order to update a file.

To fix this, add a line with to your maven-jetty-plugin configuration:

org.mortbay.jetty 
maven-jetty-plugin 
6.1.5
   
  ... 
  src/main/resources/webdefault.xml 
  

The default webdefault.xml file is found in the lib/jetty.jar at org/mortbay/jetty/webapp/webdefault.xml. Extract it to a convenient disk location and edit it to change useFileMappedBuffer to false:

 
    useFileMappedBuffer 
     false 
   

Copy the changed file into src/main/resources/ of your project.

The problem is explained more in Jetty's documentation.

Maven reusing test classes across multi modules projects

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Category: Apache Maven

Published on Friday, 18 July 2008 00:00

Written by Administrator

Hits: 31561

Maven clearly differentiate "productive code"  in each module src/main/* from unit test code in src/test/*.
In a typical multi-module projects like the one below:

componentA
|
|-moduleA
|         /src/main/java
|         /src/main/resources
|         /src/test/java
|         /src/test/resources
|-moduleB
|         /src/main/java
|         /src/main/resources
|         /src/test/java
|         /src/test/resources

Note1: Eclipse do not support multi module project as only one level of code sharing is allowed. So we have
3 eclipse projects/maven projects with a pom.xml:

• componentA with a packaging pom, and 2 module aggregated
• moduleA, parent is ../componentA/pom.xml
• moduleB   parent is ../componentA/pom.xml

Note2: eclipse has only one Class Loader, meaning that code in /src/main/java  and /src/test/java  is also exported
as dependencies between modules, while in Maven, code is not shared!

So as default by adding a dependencies in moduleB/pom.xml to moduleA, you'll only inherit moduleA src/main/java
and src/main/resources

Read more: Maven reusing test classes across multi modules projects

Better readability of source code

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Category: My Homepage

Published on Friday, 17 June 2005 00:00

Written by Administrator

Hits: 7700

I just activated the mambots Geshi (standard in Mambo 4.5.2 ) on my Homepage, now all code in my pages (between <pre> and </pre> ) will be automaticaly highlighted and colored. More than 38 languages are now supported on my homepage!

actionscript - ada - apache - asm - asp - bash - c - c_mac - caddcl - cadlisp - cpp - csharp - css - delphi - html4strict - java - javascript - lisp - lua - mpasm - nsis - objc - oobas - oracle8 - pascal - perl - php-brief - php - python - qbasic - smarty - sql - vb - vbnet - visualfoxpro - xml

I will post later post an update for Mambo 4.5.2, instead of Geshi 1.0.4 You will soon be able to use Geshi 1.0.7 and an extended Mambot for Your personal use.

Enjoy ;-)

private long startStatistics() {
		long before = System.currentTimeMillis();
		if (logger.isDebugEnabled()) {
			logger.debug("Start conversion " );
		}
		return before;
	}