EJB Concepts
Internal
EJB and JNDI
Session beans are bound to JNDI according to the following naming scheme:
ejb:/<application-name>/<module-name>/<distinct-name>/<bean-name>!<view-class-name>?stateful
where:
application-name
application-name is the name of the EAR application the session bean is deployed as part of.
If the session bean is not deployed as part of an EAR, that part is left blank.
If the session bean deployed as part of an EAR, the part is by default the name of the EAR file, without the .ear suffix. The name can be overridden in the application.xml deployment descriptor by specifying the <application-name> element.
The JNDI bindings for session bean named 'SimpleStatelessBean' in deployment unit 'deployment "stateless-ejb-example.jar"' are as follows:
java:global/stateless-ejb-example/SimpleStatelessBean!io.novaordis.playground.jee.ejb.stateless.SimpleStateless java:app/stateless-ejb-example/SimpleStatelessBean!io.novaordis.playground.jee.ejb.stateless.SimpleStateless java:module/SimpleStatelessBean!io.novaordis.playground.jee.ejb.stateless.SimpleStateless java:jboss/exported/stateless-ejb-example/SimpleStatelessBean!io.novaordis.playground.jee.ejb.stateless.SimpleStateless java:global/stateless-ejb-example/SimpleStatelessBean java:app/stateless-ejb-example/SimpleStatelessBean java:module/SimpleStatelessBean
Invoking into EJBs
TODO https://blog.akquinet.de/2014/09/26/jboss-eap-wildfly-three-ways-to-invoke-remote-ejbs/
EJB Remote Applications
An EJB remote application can be one of the following:
- a standalone Java application
- another component that runs within a application server instance, and makes invocations into remote EJBs. In this case, each deployed application will have its own EJB client context, and the application's components will share the EJB client context.
EJB Client API
JBoss EAP 6 introduced the EJB client API for managing remote EJB invocations. The EJB client API uses the EJB Client Context.
EJB Client Context
The EJB client context may be associated with, and used by more than one thread concurrently.
There can potentially be more than one EJB client contexts into a JVM. For deployed applications, each application will have its own EJB client context. Whenever that application invokes another EJB, the corresponding EJB client context is used to find the correct EJB receiver, which then handles the invocation.
For standalone applications, a remote standalone client typically has just one EJB client context backed by any number of EJB receivers
An EJB client context may contain any number of EJB receivers.
The EJB client context is configured with jboss-ejb-client.properties for standalone applications and with jboss-ejb-client.xml for applications deployed within the EAP.
EJB Receiver
An EJB receiver is a component that knows how to communicate with a server that is capable of handling EJB invocations.