Chapter 38. Interoperability between JOnAS and CORBA
This chapter describes the basic interoperability between JOnAS and CORBA using RMI-IIOP.
38.1. Accessing an EJB Deployed on a JOnAS Server by a CORBA Client
38.1.1. JOnAS Configuration
No modification to the EJB code is necessary. However, the EJB should be deployed for the iiop protocol (for example, when the build.xml is created, add the tag "protocols" and specify "iiop"). For example:
<jonas destdir="${dist.ejbjars.dir}" classpath="${classpath}"
jonasroot="${jonas.root}" protocols="iiop"/> |
If GenIC is used for deployment, the -protocols option can be used. Note also that an EJB can be deployed for several protocols. Refer to the JOnAS Configuration Guide for more details about configuring the communication protocol.
The JOnAS configuration must be modified for the JOnAS server to use RMI-IIOP. Choose the iiop protocol in the file carol.properties. Refer also to the Section 3.3 Configuring the Communication Protocol and JNDI for details about configuring the communication protocol. These modifications will make it possible to create an EJB using the RMI-IIOP protocol.
38.1.2. Using RMIC to Create IDL Files Used by the CORBA Client
To call an EJB deployed on JOnAS that is accessible through RMI-IIOP, use the rmic tool on the EJB Remote interface and EJB Home interface to create the idl files. For example:
rmic -classpath $JONAS_ROOT/lib/common/j2ee/ejb.jar -idl package1.Hello |
This action generates several idl files:
package1/Hello.idl package1/HelloHome.idl java/io/FilterOutputStream.idl java/io/IOException.idl java/io/IOEx.idl java/io/OutputStream.idl java/io/PrintStream.idl java/io/Writer.idl java/io/PrintWriter.idl java/lang/Exception.idl java/lang/Ex.idl java/lang/Object.idl java/lang/StackTraceElement.idl java/lang/ThrowableEx.idl java/lang/Throwable.idl javax/ejb/EJBHome.idl javax/ejb/EJBMetaData.idl javax/ejb/EJBObject.idl javax/ejb/Handle.idl javax/ejb/HomeHandle.idl javax/ejb/RemoveException.idl javax/ejb/RemoveEx.idl org/omg/boxedRMI/seq1_octet.idl org/omg/boxedRMI/seq1_wchar.idl org/javax/rmi/CORBA/ClassDesc.idl org/omg/boxedRMI/java/lang/seq1_StackTraceElement.idl |
Copy these files to the directory in which CORBA client development is being done.
38.1.3. CORBA Client Development
38.1.3.1. idlj
Once idl files are generated, apply the idlj tool to build Java files corresponding to the idl files (idlj = idl to java). To do this, apply the idlj tool to the Remote interface idl file and the Home interface idl file. For example:
idlj -fclient -emitAll package1/Hello.idl |
The idlj tool also generates bugged classes. Be sure to put the _read and _write method in comments in the classes _Exception.java, CreateException.java, RemoveException.java.
Additionally, the classes OutputStream.java, PrintStream.java, PrintWriter.java, Writer.java, and FilterOuputStream.java must extend Serializable and then replace
((org.omg.CORBA_2_3.portable.OutputStream) ostream).write_value(value,id()); |
with
((org.omg.CORBA_2_3.portable.OutputStream) ostream).write_value((Serializable) value,id()); |
in the write method.
38.1.3.2. The CORBA Client
Create the CORBA client:
import org.omg.CosNaming.*;
import org.omg.CORBA.*;
public class Client {
public static void main(String args[]) {
try {
//Create and initialize the ORB
ORB orb=ORB.init(args,null);
//Get the root naming context
org.omg.CORBA.Object
objRef=orb.resolve_initial_references("NameService");
NamingContext ncRef= NamingContextHelper.narrow(objRef);
//Resolve the object reference in naming
//make sure there are no spaces between ""
NameComponent nc= new NameComponent("HelloHome","");
NameComponent path[] = {nc};
HelloHome tradeRef=HelloHomeHelper.narrow(ncRef.resolve(path));
//Call the Trader EJB and print results
Hello hello=tradeRef.create();
String tr=hello.say();
System.out.println("Result = "+tr);
}
catch (Exception e) {
System.out.println("ERROR / "+e);
e.printStackTrace(System.out);
}
}
} |
