openSession()/closeSession() in SLSB

PatrickBradley · **Joined:** Thu Dec 11, 2003 11:59 am **Posts:** 24

I followed the guidelines in the FAQ:
http://www.hibernate.org/119.html#A14

and I now have openSession()/closeSession() in all of my business methods of my stateless session bean. I'm a bit worried about what what happens if an exception is thrown (Hibernate or other). Do I have to close the session everywhere I throw? What if it's a RuntimeException?

Ideally, I'd like to put openSession()/closeSession() somewhere more centralized, but I'm not sure where. Any ideas?

baliukas · **Posted:** Sat Jan 17, 2004 11:31 am

One of ways can be proxy object:

remote interface:

Code:

public interface Server
  extends javax.ejb.EJBObject {
      
      public Object invoke( String clsName , 
                                     String methodName, 
                                     Class params[] ,
                                     Object args[]
                             ) throws java.rmi.RemoteException, Exception;
      
 }

home interface :

Code:

public interface ServerHome
  extends javax.ejb.EJBHome {
      
      public Server create() throws javax.ejb.CreateException, 
                                                   java.rmi.RemoteException;
      
      
 }

implementation :

Code:

public Object invoke(String clsName, String methodName, 
                               Class params[] ,Object args[]) throws Exception{
          
          
         //INTERCEPTS ALL CALLS FROM REMOTE CLIENT 
          Object obj = lookup(clsName);      
          return  obj.getClass().
                             getMethod(methodName,params).
                                                             invoke(obj,args);
          
                   
     }

client:

Code:

public Object create(Class anyInterface){
          return Proxy.newProxyInstance(anyInterface.getClassLoader(), new Class[]{anyInterface}, new InvocationHandler(){
              
   public Object invoke( Object    obj, 
                                  Method   method, 
                                  Object[] args) throws java.lang.Throwable {
             //INTERCEPTS ALL CALLS CALLS TO REMOTE SERVER    
               return server.
                   invoke( method.getDeclaringClass(),
                        method.getName(),
                        method.getParameterTypes(),
                        args);
             }
              
              
          }
          );
      }

It is a simple way to use pseudo AOP with EJB for client, server or for both.
It needs to lookup single bean on client "Server", server can invoke method on Local/Remote bean or on POJO.

emmanuel · **Posted:** Sat Jan 17, 2004 1:45 pm

AOP is a good solution,
Generated EJBs works fine too.

PatrickBradley · **Joined:** Thu Dec 11, 2003 11:59 am **Posts:** 24

emmanuel wrote:

AOP is a good solution,

Yes it is, but I can't get it to work in Sun One appserver. I have a business delegate that I can test outside the container and I have my openSession() and closeSession() being called before and after every method. This works great outside the container. But when I deploy it and run it in the appserver, it runs as if the AspectJ stuff wasn't even there. This is my first time using AOP, so I might be doing something wrong. This is what I did:

Code:

pointcut DelegateCall(): call(public * Delegate.* (..));

before(): DelegateCall() {
  // openSession() and assign to a ThreadLocal as in Thread Local Session doc
}

after(): HSPManagerCall() {
  // closeSession()
}

Quote:

Generated EJBs works fine too.

I am already generating EJBs. It's just really annoying to have to catch all the exceptions so that I can close my session, then rethrow the exceptions. There really must be a better way to do this.

emmanuel · **Posted:** Mon Jan 19, 2004 5:43 pm

I don't use AspectJ but cglib2 to develop a dynamic interceptor. It works fine on Weblogic.

baliukas · **Posted:** Tue Jan 20, 2004 8:59 am

PatrickBradley wrote:

I am already generating EJBs. It's just really annoying to have to catch all the exceptions so that I can close my session, then rethrow the exceptions. There really must be a better way to do this.

Close it in "finally" block and declare all exeptions in method declaration or wrapp all exeptions in single "catch(Exception e)" block and rethrow as runtime exception.