EJB 3.1 as RESTFul webservice

[Claude Moore]

I'm searching to understand the machinery needed to expose SLSB as RESTFul webservices. If I define and implement a simple EJB inside a Web Application project I just need to:

a) define Local interface and EJB implementation like in the following code:

@Stateless
@Local(MyEjbLocal.class)
@Path("/localejb")
public class MyEjb implements MyEjbLocal {

    /**
     * Default constructor. 
     */
    public MyEjb() {
        // TODO Auto-generated constructor stub
    }

    @GET
	@Path("sayHello")
	@Produces("text/plain")
	@Override
	public String sayHello() {
		return "Hello from EJB ";
	}

}

.....



public interface MyEjbLocal {
	public String sayHello();
}

b) define an extension of javax.rs.core.Application like the following code:

@ApplicationPath(value = "/root")
public class RESTFullHook extends Application {
	public Set<Class<?>> getClasses() {
		Set<Class<?>> s = new HashSet<Class<?>>();
        s.add(MyEjb.class);
        return s;
    }
}

and the whole thing works: when the appserver starts (in this case, it's WebSphere, but I think that's irrelevant), the RESTFul service is exposed, and in RAD I can see a Services/REST entry in my project.

Anyway, I'd like to read your suggestions about exposing as REST services EJBs which are defined inside an EJB 3.1 project: how should I proceed ?
Of course I may define a WrapperBean, inject in it all EJBs whose method I want expose as service, but I'd like to know If there's another solution to this problem.

Thank you for your help.

[Claude Moore]

I'm afraid I've written a bunch of nonsense in this post.


Searching more on the web, I found out that it's simply not possible to expose as RESTFul webservices EJBs that are deployed as EJB Project, i.e, arent'part of a WAR project.
That sound reasonable, because EJB in EJB projects are not meant to be accessed via HTTP; indeed, if you try and expose them as JAX-WS webservices, RAD creates a Dynamic
web project as requests router.

So, I think that I'll try and follow a BusinessDelegate pattern implementation, for example like this :

// This is a simple POJO class

@ApplicationPath(value = "/root")
@Path("slbs")
public class RESTFullHook extends Application {

	
	@Path("service/{param1}")
	@GET
	public Response doSomething(@PathParam("param1") String param1) {
		// Here should go the lookup based upon {EJB} param
                IEJBInterface lookup = ....
		// Processing ....
                SomeObject obj = lookup.doSomething(....); 
		// getting response
		return Response.ok(obj)....
	}
	
}

Hope this may help someone else looking for solving similar problems, other suggestions are wellcome (of course !)

By the way: I have again to understand how multithreading invocations are handled....

[Sujeeth Pakala]

Hello Claude

Thanks for posting the problem and solution ;-)

Can't the EJBs are declared in EJB project, package as jar, kept in WEB-INF/lib folder as jar file and access them via HTTP as REST ? This way EJBS can also be accessible via other clients and more reusable. No ?

[Claude Moore]

Yes, you may deploy EJB within a WEB Application and all works, but for personal taste I prefer to keep things separated (EJB modules separated from WAR modules).