Is it possible to influence which EJB is called (remote / local)?

[a3aan]

At our project we are successfully using the remote EJB lookup as can be found in https://docs.jboss.org/author/display/AS71/EJB+invocations+from+a+remote+server+instance.

Our setup is the following: we have two instances of JBoss running in domain setup on a remote server. The first one is our webapplication jboss and the second one runs all our backend services (as EARs containing EJBs). The webapplication JBoss 'knows' the backend JBoss so remote EJB calls from the webapplication JBoss to the backend JBoss are working fine.

Locally we also run a JBoss instance for development purposes in standalone mode. This local JBoss also 'knows' the backend JBoss so when developing for instance a webapplication this webapplication can call the remote EJB's as well. This also gives our developers the opertunity to deploy an EAR containing one or more EJBs (which is also running on the backend JBoss) locally. This way the EJBs can easily be debugged and developed. And by just undeploying the EAR the locally running webapplication will call the remote EJB on the backend server again.

But... somehow at the moment we are facing the problem that it is not default behaviour that when the same EJB can be found locally and remote it will prefer the local EJB above the remote one. Is this some configuration option or something that we can influence programmatically?

[jaikiran]

Adriaan, welcome to the forums

Adriaan Wisse wrote:

But... somehow at the moment we are facing the problem that it is not default behaviour that when the same EJB can be found locally and remote it will prefer the local EJB above the remote one. Is this some configuration option or something that we can influence programmatically?

Yes, there's a server side implementation of DeploymentNodeSelector which "prefers" the local server if there are multiple servers which can handle that EJB. There are reasons to do that since if the local server can handle the request there's no need to do the expensive network calls on the remote server. This is the implementation which routes it to the local node https://github.com/jbossas/jboss-as/blob/master/ejb3/src/main/java/org/jboss/as/ejb3/remote/LocalEJBReceiverPreferringDeploymentNodeSelector.java#L31.

If you want to override that behaviour then you can implement your own DeploymentNodeSelector (which selects and returns appropriate node) and then package a jboss-ejb-client.xml in the application and set the deployment-node-selector attribute value to that class name. Here's an example of the xml https://github.com/jbossas/jboss-as/blob/master/testsuite/integration/basic/src/test/java/org/jboss/as/test/integration/ejb/client/descriptor/jboss-ejb-client_1_2.xml#L24

[a3aan]

Hi Jaikiran,

Thanks for your helpful answer. According to your answer I don't need to write our own implementation because the LocalEJBReceiverPreferringDeploymentNodeSelector should exactly do what we need. Or do I misunderstand you?

So I will debug it and find out what goes wrong in our specific case and let you know.

[a3aan]

Can you tell me in which jar I can find the mentioned class (LocalEJBReceiverPreferringDeploymentNodeSelector)?

[jaikiran]

This wasn't available in AS 7.1.1.Final. You'll need the latest nightly build which contains this fix.

[a3aan]

Hmm, thats a bit of a problem. Can you give any idea about when a newer version (containing this fix) of JBoss 7 will be released? We will need some stable / final version before the end of october.

[jaikiran]

Adriaan Wisse wrote:

Hmm, thats a bit of a problem. Can you give any idea about when a newer version (containing this fix) of JBoss 7 will be released? We will need some stable / final version before the end of october.

I don't know the date. But there's a stable tag from which you can build this fix https://github.com/jbossas/jboss-as/tree/7.1.2.Final