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Migrating EJB, ECO/Java and JCORBA Applications

This chapter provides information on migrating EJB, ECO for Java and JCO applications from the Oracle Application Server to OC4J in Oracle Application Server 10g.

Topics discussed are:

• Migrating EJBs to OC4J

• Migrating ECO/Java to OC4J

• Migrating JCORBA to OC4J

Migrating EJBs to OC4J

To migrate EJBs from Oracle Application Server 4.x to OC4J, you must modify code in the following areas:

• Deployment Descriptors

• Client Code

• Logging (Server Code) (if applicable)

  Note: Oracle Application Server EJB does not comply to EJB standards, while Oracle Application Server 10g EJB complies with complete EJB 2.0 specifications. Modify your code accordingly during the migration.

The following sections describe these changes.

Deployment Descriptors

OC4J conforms to XML file configuration that complies to J2EE 1.2 specifications.

See Also: Oracle Application Server Containers for J2EE Support for JavaServer Pages Developer's Guide

Client Code

Changes to the client code are made in the initial context call using JNDI. The hashtable passed to the initial context call must contain all of the following properties:

• javax.naming.Context.URL_PKG_PREFIXES

• javax.naming.Context.SECURITY_AUTHORIZATION

• javax.naming.Context.SECURITY_PRINCIPAL

• javax.naming.Context.SECURITY_CREDENTIALS

  See Also: Oracle Application Server Containers for J2EE User's Guide

You must also change the URL that accesses your EJB home to the OC4J:

ORMI://<host>:<port>/<path>/<bean>

For example:

ORMI://myhost:2481/test/myBean
ORMI://host/port/est/bean

Logging (Server Code)

If application logging was done in Oracle Application Server, remove all references to oracle.oas.ejb.Logger from your EJB code.

Migrating ECO/Java to OC4J

When migrating ECO for Java (ECO/Java) in Oracle Application Server to OC4J in Oracle Application Server 10g, you must change server code described in this section, as well as change deployment descriptors and client code described in the previous section for EJB migration.

To make your ECO/Java components compatible with OC4J, you must modify the implementation file, the remote interface file, the home interface file, and deployment descriptors.

Remote Interface

Change the remote interface to extend javax.ejb.EJBObject instead of oracle.oas.eco.ECOObject. Each method must throw java.rmi.RemoteException.

Home Interface

Change the home interface to extend javax.ejb.EJBHome instead of oracle.oas.eco.ECOHome.

The created method must throw javax.ejb.CreateException and java.rmi.RemoteException instead of oracle.oas.eco.CreateException.

Implementation Class

Make the following changes to the implementation class:

1. Remove all occurrences of, and references to, oracle.oas.eco.Logger.

2. Change all occurrences of oracle.oas.eco.* to javax.ejb.*.

3. Change ECOCreate method to ejbCreate method.

4. Change ECORemove method to ejbRemove method.

5. Change ECOActivate method to ejbActivate method.

6. Change ECOPassivate method to ejbPassivate method.

7. Since OC4J uses XML files for deployment, you have to create appropriate deployment files.

Migrating JCORBA to OC4J

Oracle Application Server versions 4.0.6 and 4.0.7 provided a component model, Java CORBA Objects (JCO), which is a precursor to the ECO/Java model. Oracle Application Server 10g does not support CORBA objects. You must recode your CORBA objects as EJBs. This section discusses migration from JCO in Oracle Application Server to OC4J in Oracle Application Server 10g.

To migrate to OC4J, you must modify the server and client code as discussed in this section. To modify the server code, you must modify the remote interface, create a home interface, modify the JCORBA object implementation, and make parameters serializable.

See Also: You must also modify the deployment descriptors as discussed in "Deployment Descriptors".

Remote Interface

Make the following changes to the remote interface:

1. Convert all occurrences of org.omg.CORBA.Object or oracle.oas.jco.JCORemote to javax.ejb.EJBObject.

2. Throw java.rmi.RemoteException for all methods in the interface.

Home Interface

You must to create a home interface, as defined in the EJB specification. The following is an example.

import javax.ejb.*;
import java.rmi.RemoteException;
public interface ServerStackHome extends EJBHome
{
   public ServerStackRemote create() throws CreateException, RemoteException;
}

Object Implementation

Complete the following steps to migrate the implementation class:

1. Change import oracle.oas.jco.* to import javax.ejb.*.

2. Check that the class implements javax.ejb.SessionBean, or javax.ejb.EntityBean.

   Note: The JCORBA Lifecycle is not supported within OC4J. If the JCORBA object implements oracle.oas.jco.Lifecycle, you must remove it.

3. Remove any logger references.

4. Move any initialization operations to the ejbCreate() method.

5. Save the session context passed into the setSessionContext() method in an instance variable.

6. Ensure that all public methods in the class throw java.rmi.RemoteException.

7. Change any ObjectManager type to SessionContext type. Table 4-1 maps the methods in the ObjectManager class to methods in the SessionContext class.

   Table 4-1 ObjectManager and SessionContext Methods

   SessionContext Method	ObjectManager Method
   getEnvironment()	getEnvironment()
   Parameter passed to setSessionContext()	getObjectManager()
   getEJBObject()	getSelf()
   getEJBObject().remove()	revokeSelf()
   getUserTransaction()	getCurrentTransaction()

Make Parameters Serializable

If any user-defined parameters are being passed in the remote interface, ensure that the classes implement java.io.Serializable.