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RE: [eclipselink-dev] EntityManager usage of ClientSession

1) Currently the lifecycle of the ClientSession matches that of the EntityManager as all EntityManagers are extended from the Provider's point of view.  Because they are extended the UOW, EntityManager and ClientSession all have the same life termination point. 
 
2) I agree with Andrie and James.
 
3) Andrei had a good idea.
--Gordon
-----Original Message-----
From: eclipselink-dev-bounces@xxxxxxxxxxx [mailto:eclipselink-dev-bounces@xxxxxxxxxxx]On Behalf Of Doug Clarke
Sent: Wednesday, February 20, 2008 8:38 AM
To: Eclipselink-Dev (E-mail)
Subject: [eclipselink-dev] EntityManager usage of ClientSession

Developers,
 
On the TopLink forum there is a customer trying to use proxy authentication. Our documentation and a similar thread on the JDeveloper forum show the usage of proxy authentication using a SessionEventListener and a custom call to Server.acquireClientSession(db-login). Using this within JPA is proving challenging. The SessionEventListener can be easily introduced using a persistence unit property but addressing the proxy credentials is more challenging:
        Login login = (Login)serverSession.getLogin().clone();
        
        login.setProperty("proxytype", Integer.toString(OracleConnection.PROXYTYPE_USER_NAME)); 
        login.setProperty(OracleConnection.PROXY_USER_NAME, "hr"); 
        ConnectionPolicy connectionPolicy = new ConnectionPolicy(login);
        // for vpd support connectionPolicy.setShouldUseExclusiveConnection(true);    
       
        clientSession =  serverSession.acquireClientSession(connectionPolicy);
I took a quick look through our implementation of EntityManager and we have one case where we acquire a client session in the process of acquiring a UnitOfWork but in most cases we simply acquire the UnitOfWork from the server session. I know this internally results in a client session but it does feel weird. I would have expected us to acquire a client session and hold it in the EntityManager (possibly during construction) and then acquire repeatable-read UnitOfWork or non-synchonized UnitOfWork as needed form the client session. This would allow the isolated client session, when used, to have a life-cycle equivalent to that of the EntityManager.
 
I guess I have a few questions:
 
1. Should our EntityManagerImpl wrap a client-session instead of a server session to better handle the isolated client session's cache lifecycle matching that of the EntityManager? If we need a server session we can always get it through getParent()
 
2. How can we address proxy authentication through JPA? We need to change how we create the client session within the EntityManagerImpl and thus the lifecycle of the client session is important to this discussion. See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=219434
 
3. Does anyone have an idea of how I could work-around our current implementation limitations to make proxy authentication work through our current JPA implementation in EclipseLink?
 
Cheers,
 
Doug
 
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Doug Clarke
Director of Product Management, Oracle TopLink 
Oracle Server Technologies
45 O'Connor, Suite 4000 | Ottawa, ON  K1P 1A4 Canada
+1 613 288 4617
 

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