Lookup of same EJB on multiple servers

问题

I am trying to do a lookup from one deployment to another deployment, using exactle the same bean implementations. It is basically a consumer/producer setup with the same beans in both deployments on both machines.

ear
    ejb-api
        com.example.bean
            ConsumerBean
            ProducerBean
    ejb-jar
        com.example.bean
            ConsumerBeanRemote
            ProducerBeanRemote

The ProducerBeanRemote should look up the ConsumerBeanRemote and call its public method.

Our machines are communicating like this:

(Machine A) ProducerBeanRemote --> (Machine B) ConsumerBeanRemote
(Machine A) ProducerBeanRemote --> (Machine C) ConsumerBeanRemote
(Machine A) ProducerBeanRemote --> (Machine D) ConsumerBeanRemote

You get the idea...

So the problem is, it doesn't work. I tried to do a manual lookup using the jboss-as-ejb-client libraries, which didn't work because JBoss locks the EJB selector while starting its container (AND I bet the spec has something to say about manual lookups in a Java EE environment). The next thing I tried was doing a lookup using the feature from Spring, to no avail.

We are using the JBoss Application Server 7.1.1.Final.

I bet there has to be a way to accomplish my setup and I would greatly appreciate any help from the community.

UPDATE:

To connect from ProducerBeanRemote to ConsumerBeanRemote, we need the possibility to specify the remote InitialContext at runtime via configuration.

Properties properties = new Properties();
properties.put("remote.connectionprovider.create.options.org.xnio.Options.SSL_ENABLED", "false");
properties.put("remote.connections", "default");
properties.put("remote.connection.default.host", "remote-host");
properties.put("remote.connection.default.port", "4447");
properties.put("remote.connection.default.connect.options.org.xnio.Options.SASL_POLICY_NOANONYMOUS", "false");

EJBClientConfiguration ejbClientConfiguration = new PropertiesBasedEJBClientConfiguration(properties);
ContextSelector<EJBClientContext> ejbClientContextSelector = new ConfigBasedEJBClientContextSelector(ejbClientConfiguration);
EJBClientContext.setSelector(ejbClientContextSelector);

StatelessEJBLocator<T> locator = new StatelessEJBLocator<>(viewType, appName, moduleName, beanName, distinctName);
return EJBClient.createProxy(locator);

The resulting exception is

java.lang.SecurityException: EJB client context selector may not be changed at org.jboss.ejb.client.EJBClientContext.setSelector(EJBClientContext.java:181)

We understand that this exception is thrown because of https://issues.jboss.org/browse/AS7-2998, so the question remains: How can we remotely call the same beans in a clean and configurable way?

回答1:

Nearly the same question as described here: JNDI lookup from one server to many configurable servers

It seems to be impossible to get a reliant connection between multiple servers via EJB, so we ended up using JMS for our server to server communication. Maybe thats an option for you, too.

回答2:

You didn't tell me much about your setup or any errors you're getting so I can't really help you troubleshoot them. I just struggled through getting a remote ejb client to work as well and these resources were absolutely invaluable:

https://docs.jboss.org/author/display/AS72/EJB+invocations+from+a+remote+client+using+JNDI https://docs.jboss.org/author/display/AS71/Remote+EJB+invocations+via+JNDI+-+EJB+client+API+or+remote-naming+project http://blog.jonasbandi.net/2013/08/jboss-remote-ejb-invocation-unexpected.html#comment-form http://www.mastertheboss.com/jboss-as-7/jboss-as-7-remote-ejb-client-tutorial/page-2

Good luck!

回答3:

The setup is possible. There is no need to reengineer the whole code using JMS.

It is possible to call remote ejb beans on different JBOSSAS7 servers from a single POJO client using your own custom Selector for the EJBClientContext. With the code mentioned, you are able to register different scopes for different servers

See an example from the jboss developers here

https://community.jboss.org/thread/223419?tstart=0

https://github.com/wfink/jboss-as-quickstart/blob/ejb-clients/ejb-clients/jboss-api/src/main/java/org/jboss/as/quickstarts/ejb/clients/selector/CustomScopeEJBClientContextSelector.java

来源：https://stackoverflow.com/questions/22838876/lookup-of-same-ejb-on-multiple-servers