Creating Web Services from ADF Business Components Using Stateless EJB Session Beans

You can create a web service from ADF Business Components by publishing the application module as a service session bean. This is a good technique to use if the web service needs to interact with other EJB session beans as part of its implementation. Another way of creating a web service from ADF Business Components is generating a web service class for the application module, and creating the web service from it.

You can configure ADF Business Components application modules to deploy as EJB session beans. For more information, see Packaging ADF Business Components as an EJB Session Bean. By default, these are stateful session beans, and to create web services from them they have to be changed into stateless session beans.

The steps below illustrate turning a stateful ADF Business Components based session bean into a stateless session bean.

To change the bean to a stateless session bean:

1. In the navigator, double-click the bean <AppModuleName> Server.java.
2. Comment out the  createApplicationModule() call from the  ejbCreate(), leaving an method that looks like:

   
   public void ejbCreate() throws java.rmi.RemoteException, javax.ejb.CreateException
   {
       // To make stateless, comment this line out
       // createApplicationModule("mypkg.MypkgModule");
   }           

For each method in the bean that implements a method on the session bean's remote interface perform the following steps to augment the existing method body. You must do this for each exported method in your application module:
• Copy/paste the   createApplicationModule("mypkg.MyModule") line from above, and put it first, just inside the  try .
• If you want to pass environment settings that you have set as part of a Business Components configuration, you can optionally pass the desired configuration name as the second parameter to this method.
  • Add a line to connect the application module to a datasource.
  • Add a  catch block to handle the   javax.ejb.CreateException, making sure that you use the fully qualified form.
  • Add a  finally block that contains a call to  removeApplicationModule()
  So, for example, the  someExposedMethod() above would end up looking like this:

// NOTE: Need to add imports for javax.ejb.CreateException and java.rmi.RemoteException
public String someExposedMethod(int x) throws java.rmi.RemoteException
{
	try
    {
      // (Step 1) Add this line -- Create the application module 
      createApplicationModule("mypkg.MypkgModule");
          
      // (Step 2) Add this line -- Connect the appmodule to a datasource using the
      // ejb-location name of the datasource from the data-sources.xml file
      getApplicationModule().getTransaction().connectToDataSource(null,"jdbc/OracleDS",false);
         
      return getMypkgModule().someExposedMethod(x);
     }
     // (Step 3) Add this catch block
     catch(javax.ejb.CreateException ex)
     {
     	throw new RemoteException("Create error", ex);
     }
     catch(oracle.jbo.JboException ex)
     {
     	//  Convert JboException to service exception below
        //  Business methods shouldn't throw RuntimeException
        ex.printStackTrace();
        throw ex;
      }
        // (Step 4) Add this finally block to remove the appmodule
        finally {
     	   // Add this line -- Remove the application module          
    	    removeApplicationModule();
       }
   }    

• Lastly, you need to edit the EJB Session Bean properties to change the setting from Stateful to Stateless. In the navigator, double-click the session bean to display the EJB Module Editor.
• Select the EJB, and in Session Bean Information change the Session Type to Stateless .

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