8 Replies Latest reply on Jan 8, 2008 6:26 AM by pmuir

    Injecting Remote EJBs

    starf666
    starf666 Jan 7, 2008 5:29 AM

      Hello Seam community,

      I am just starting a new project and want to use the seam framework. The system architecture demands that parts of the application are on a different machine than the main web-system. How can I inject (with @EJB annotation) remote EJBs into Beans located on the main machine. I guess I have to give the address of the remote machine somewhere, maybe jndi.properties? Or am I heading in the completely wrong direction. I looked through a lot of EJB tutorials, docs and books but they only describe injection in simple java clients or plain local injection.

      Thanks in advance,
      Martin

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        • 1. Re: Injecting Remote EJBs
          cavani
          cavani Jan 7, 2008 9:34 AM (in response to starf666)

          I am using this:

          Properties env = new Properties();
env.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
env.put(Context.URL_PKG_PREFIXES, "org.jboss.naming:org.jnp.interfaces");
env.put(Context.PROVIDER_URL, "jnp://192.168.1.1:1099");

Context ctx = new InitialContext(env);

return (ManagementService) ctx.lookup("tlon/ManagementServiceBean/remote");


          where there is two ears on different AS instance (and machines). "tlon" is the name of second EAR. "ManagementService" interface is deployed in both. Both application are Seam basead.

          I think (but don't tryed) tou could use factory or unwrap annotation to encapsulate and use in annotation for injection.

          Thanks,



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          • 2. Re: Injecting Remote EJBs
            cavani
            cavani Jan 7, 2008 9:59 AM (in response to starf666)

            Something like this:

            @Name("managedRemoteServer")
@Scope(ScopeType.STATELESS)
public class ManagedRemoteServer
{

 @Unwrap
 public ManagementService getRemoteServer()
 {
 try
 {
 Properties env = new Properties();
 env.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
 env.put(Context.URL_PKG_PREFIXES, "org.jboss.naming:org.jnp.interfaces");
 env.put(Context.PROVIDER_URL, "jnp://192.168.1.1:1099");

 Context ctx = new InitialContext(env);

 return (ManagementService) ctx.lookup("tlon/ManagementServiceBean/remote");
 }
 catch (Exception e)
 {
 e.printStackTrace();
 }

 return null;
 }

}


            And: 

            
 @In
 private ManagementService remoteServer;


            Obs.: I didn't test this...

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            • 3. Re: Injecting Remote EJBs
              cavani
              cavani Jan 7, 2008 10:11 AM (in response to starf666)

              [sorry... I will stop....]

              I think that this is your answer:


              In addition, EJB 3.0 dependency injection only works in the local JNDI. Hence you cannot inject objects from remote servers.


              from:

              http://trailblazer.demo.jboss.com/EJB3Trail/serviceobjects/injection/index.html

              Thanks,

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              • 4. Re: Injecting Remote EJBs
                andyd
                andyd Jan 7, 2008 3:34 PM (in response to starf666)

                You may be able to acheive what you want to using the web services support, but it isn't something I have experience using.

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                • 5. Re: Injecting Remote EJBs
                  starf666
                  starf666 Jan 8, 2008 4:10 AM (in response to starf666)

                  Thanks for the answers so far.

                  [sorry... I will stop....]

I think that this is your answer:

Quote:

In addition, EJB 3.0 dependency injection only works in the local JNDI. Hence you cannot inject objects from remote servers.


from:

http://trailblazer.demo.jboss.com/EJB3Trail/serviceobjects/injection/index.html


                  I guess that's the answer albeit I hoped it wouldn't. Would clustering get me anywhere? I don't know much about it. I am not sure I could use different resources on different cluster nodes. A part of the whole application must run on a Windows server while the web part should be able to run on linux. Else I will have to do the lookup manually, what would mess up my code a bit.

                  P.S.: Is injection of remote EJBs not possible in JBoss (4.2) or is it not possible in EJB3 in general? Wouldn't it be a cool feature?


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                  • 6. Re: Injecting Remote EJBs
                    pmuir
                    pmuir Jan 8, 2008 5:25 AM (in response to starf666)

                    Ask about remote EJB injection on the EJB3 forum ;)

                    Cavani's second answer is the right way to expose a remote ejb to Seam.

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                    • 7. Re: Injecting Remote EJBs
                      starf666
                      starf666 Jan 8, 2008 6:12 AM (in response to starf666)

                      So this has nothing to do with seam? I didn't expect this to be so unlikely in the development of enterprise (web) systems.

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                      • 8. Re: Injecting Remote EJBs
                        pmuir
                        pmuir Jan 8, 2008 6:26 AM (in response to starf666)

                        Injection of EJB3s using @EJB is not Seam, no. I suspect you will get a better informed response on the EJB3 forum.

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