Re: How to call an ejb from an ejb from another applicartion server
On Nov 19, 11:54 am, Andre Broers <broe...@gmail.com> wrote:
Doesn't matter.. The problem I face is the following:
When I try to call an ejb on another server I don't think it will work
with the @EJB annotation. The way I think I have to do it is the
Initial Context of the server to be called to get the Bean(Proxy)
instance. This works when I hardcode the properties to get the Initial
Context in the EJB. What I'm searching for is the preferred way to do
it dynamic. Maybe an ejb reference but I see only examples calling an
ejb in the same jvm.
The automatic dependency discovery relies on JNDI. It's not magic.
However, to get a remote app server's beans in the right places will
probably require some vendor-specific configuration info.
Let's say you have a session bean named com.example.HelloWorld with a
method
@EJB
public void setMessageProvider (MessageProvider provider) {...}
through which a second EJB (implementing MessageProvider) is
injected. When the container goes to populate the properties of the
HelloWorld bean, it looks up the following JNDI name:
java:comp/env/com.example.HelloWorld/messageProvider
and, if it finds an object there that implements MessageProvider, it
injects it.
There is a little bit of extra magic involved when there is a
MessageProvider-implementing bean in the same application: the app
server is required to automatically map it to that name because its
interface matches the required interface of the injection target. You
can do a lookup for that name in your code yourself and find the
MessageProvider there, if your server follows the rules, even if you
never explicitly told anything to put it there.
Nothing about injection *requires* that the MessageProvider object at
that name be from the local container, though. Using container-
specific configuration you can put any object you like under that name
in the right namespace, at which point injection will pick it up and
use it.
The real problem is mapping an external server's EJBs into the
java:comp/env/ namespace of the right EJB on the local server. Since
you haven't specified which server(s) are involved, I can't offer you
anything concrete beyond "check the docs" and look up "remote jndi" or
"federated jndi" to see if there are any clues there.
-Owen