[jboss-user] [EJB 3.0] - Re: Requesting the EJB container to remove an instance

[pete.muir@jboss.org]

I talked to ALR about this a bit, here is a precis:

"Andrew Rubinger" wrote : So maybe you can explain a couple things then I'll weigh in? "This needs to be in a portable way"

The standard WB requirement - that WB must operate on other AS than JBoss - we can't have JBoss code in WB itself - if we do need to make a AS specific call we have to do it through the SPI
"Andrew Rubinger" wrote :  And you want to invoke upon what object? The proxy from JNDI?

The problem is not that i need to invoke on an EJB but request the EJB container remove it.

Then, we talked about the background:

We need to remove ejbs (e.g. when the coversation context is destroyed), if there is a Session bean proxied instance stored in a context, it get's cleaned up automatically. 

"Andrew Rubinger" wrote : And you can't call @Remove ?

We can't call @Remove as there might be multiple @Remove methods (which one to we call?) or there might be parameters to the remove method (how do we know what they are)

"Andrew Rubinger" wrote : So you want to remove the backing session, and have no callback upon the SFSB.  Which is possible but feels like a real back-door approach...

The @PreDestroy callback should still be executed. In other words, if we did this through bytecode instr, it would be like adding in a @Remove public void wbRemove() {} method

Then, I described a possible SPI Web Beans could use:

interface EJBInstance<T> implements Serializable {
  | 
  |    public void remove();
  |    T getInstance();
  | 
  | }

and an addition to the EJBResolver Web Beans SPI:

interface EJBResolver {
  | 
  |   // ...
  | 
  |   EJBInstance resolve(String jndiName);
  | }

Where Web Beans would use it like:

// initial lookup
  | EJBInstance ejb = ejbResolver.lookup(jndiName);
  | // Some requests go by, JSR299 context needs destroying
  | // destroy
  | ejb.remove();

for example, in JBoss we could implement this like:

class JBossEjbInstance<T> implements EjbInstance<T> {
  | 
  |    Object proxy;
  |    String jndiName;   
  | 
  |    JBossEjbInstance(String jndiName) {
  |       this.jndiName = jndiName;
  |    }
  | 
  |    private init() {
  |       if (proxy == null) {
  |          proxy = getInitialContext().lookup(jndiName);
  |          if (!(proxy instanceof Serializable))
  |             throw new IllegalStateException();
  |       }
  |    }
  | 
  |    public T getInstance() {
  |       init();
  |       return (T) instance;
  |    }
  | 
  |    public void remove() {
  |       ((StatefulSessionProxy) instance).remove();
  |    }
  | }
      
"Andrew Rubinger" wrote : Why Serializable?

Because the proxy needs e.g. to be serialzied to http session

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