[jboss-user] [EJB 3.0 Development] New message: "Re: Externalizing Scope: Resolving EJB References and Endpoints"

[Andrew Rubinger]

User development,

A new message was posted in the thread "Externalizing Scope: Resolving EJB References and Endpoints":

http://community.jboss.org/message/524041#524041

Author  : Andrew Rubinger
Profile : http://community.jboss.org/people/ALRubinger

Message:
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Some notes from our discussion today:
 
This cannot work:
 
//API:
/**
 * All EJB3.x SFSBs will have this bound into JNDI
 * at default: [appName]/moduleName/beanName/home
 */
interface StatefulSessionHome
{
    void remove(StatefulSessionHandle)
 
    boolean exists(StatefulSessionHandle);
 
    <T> T create(T type) throws IllegalArgumentException;
}
 
//API:
/**
 * All SFSB proxies may be cast to this type
 * by the client
 */
interface StatefulSessionHandle
{
    // Marker only from the client view   
}
 
//SPI:
/**
 * This is how the container knows the ID of the session to remove;
 * all SFSB proxies will implement this method
 */
interface StatefulSessionHandleProvider extends StatefulSessionHandle
{
     Object getId();
}
 
 
// Usage:
StatefulSessionHome home =  (StatefulSessionHome)context.lookup("beanName/home");
MyBusiness bean = home.create(MyBusiness.class);
home.remove((StatefulSessionHandle)bean);
 
// Traditional JNDI lookup removal:
MyBusiness bean = context.lookup("beanName/remote");
home.remove((StatefulSessionHandle)bean);

 
Again, this is because we can't define *any* methods upon a proxy which is for business interfaces; we could introduce conflicts in method names.  In the case above, no user code could have "getId();" for example.
 
An alternative way is to do something like have a Home per EJB Container.  Then the home knows how to go into the internals of the proxy handler to extract the ID.  Jaikiran wrote up a nice example:
 
/***************** client (weld-int) *********************/
// user looks up or injects a SFSB (as usual)
UserSFSBInterface proxy = ...//get it as usual
 
// now get a StatefulSessionHandleProvider (this needs discussion, but let's say it's available in JNDI for each SFSB)
StatefulSessionHandleProvider handleProvider = ctx.lookup("beanName/handleprovider");
StatefulSessionHandle handle = handleProvider.getHandle(proxy);
// do some stuff
handle.destroy();
 
 
 
/***************** SPI*********************/
StatefulSessionHandleProvider
{
  StatefulSessionHandle getHandle(Object proxy);
}
 
StatefulSessionHandle
{
  destroy();
 
}
 
/***************** SPI implementation (for nointerface view) *********************/
// Individual handle provider impl
JavassistProxyBasedHandleProvider implements StatefulSessionHandleProvider
{
 
 StatefulSessionHandle getHandle(Object proxy)
 {
  // do some checks on proxy 
  // and return a handle
  new JavassistBasedSFSBHandle(proxy)
 }
}
 
// JavassistBased handle for nointerface view
JavassistBasedSFSBHandle implements StatefulSessionHandle
{
 
  Serializable sessionId;
 
  JavassistBasedSFSBHandle(Object proxy)
  {
     // this knows the magic to get the session id from proxy
    this.sessionId = doSomeMagicOnProxy();
    
  }
 
  destroy()
  {
    // destroy the session using hte session id
       container.destroy(this.sessionId);
  }
 
}

 
Too bad here we'd need a Home handle (HandleProvider in the example above) per container type.
 
S,
ALR

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