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Monday November 14, 2005

Developing J2EE clients for Sun Application server In last post I wrote about EJB client for JBoss, today I would like to write introduction about J2EE clients for Sun Application server. You have two ways for devloping the client: using ACC or without it.
I guess that many users asks what this acronym stands for? ACC is Application Client Container. What is it? The Application client container includes a set of java classes, libraries and others files that are required for and distributed with Java clients programs that are executed in their JVM. The ACC manages the execution of J2EE app clients according to security, ... For instance, authentication techniques are provided by the client container and are note under control of the application client component. These security constraints are defined in deployment descriptor. I would like to develop this type of the client in next post.
Today, I will create simpler client that access EJB on remote server. This client doesn't use ACC. To access and EJB perform these steps:

• Instantiate Initial context with deafult constructor:

      InitialContext ctx = new InitialContext();
    

• In client code, look up the home object of your bean. Note, your bean should have remote interface since client is executed on different JVM and machine.

      Object obj = ctx.lookup("beanName");
      BeanHome home = (BeanHome)PortableRemoteObject.narrow(obj, BeanHome.class);
    

  You can find beanName in server specific DD sun-ejb-jar.xml, the element jndi-name.
• Add these libraries j2ee.jar and appserv-rt.jar on project classpath. They are avalaible in $SUN_APP_SERV/lib directory. Don't forget package these libraries with your project and then move on remote server.
• Last step is specify ORBHostname and ORBPort for communication with remote server. You should use these JVM arguments, right-click on project node and in Properties window go to Run. Here is JVM argument text box where you can specify these arguments. Note, these arguments are valid running project in NetBeans.

       -Dorg.omg.CORBA.ORBInitialHost=ORBHostname -Dorg.omg.CORBA.ORBInitialPort=ORBPort
     

  ORBHostname is the Application server hostname and ORBPort is port for ORB port, default 3700.
  I'm using this bash script for running clients on remote machines:

       #!/bin/sh
       JAVA_HOME="/usr/java/jdk1.5.0_02"
       J2EE_LIB="/lib"
       export JAVA_HOME
       CLASS_PATH="$J2EE_LIB/j2ee.jar:$J2EE_LIB/appserv-rt.jar:MyClient.jar"
       ARGS="-Dorg.omg.CORBA.ORBInitialHost=Hostname -Dorg.omg.CORBA.ORBInitialPort=3700"
       $JAVA_HOME/bin/java $ARGS -cp $CLASS_PATH pkg.Main
       exit 0
     

• Run client on remote machine.