Your First JAX-RS Service - RESTful Java with JAX-RS 2.0 - page 38

... the implementation ...

}
The only caveat with this approach is that the concrete subclass must annotate itself with the
@Path annotation to identify it as a service class to the JAX-RS provider.

Deploying Our Service
It is easiest to deploy JAX-RS within a Java EE-certified application server (e.g., JBoss) or
standalone Servlet 3 container (e.g., Tomcat). Before we can do that, we need to write one
simple class that extends javax.ws.rs.core.Application . This class tells our application
server which JAX-RS components we want to register.

package package javax . ws . rs . core ;

import import java.util.Collections java.util.Collections ;

import import java.util.Set java.util.Set ;

public public abstract abstract class class Application Application {

private private static static final final Set < Object > emptySet = Collections . emptySet ();

public public abstract abstract Set < Class <?>> getClasses ();

public public Set < Object > getSingletons () {

return

return emptySet ;

}

}

The getClasses() method returns a list of JAX-RS service classes (and providers, but I'll
get to that in Chapter 6 ). Any JAX-RS service class returned by this method will follow the
per-request model mentioned earlier. When the JAX-RS vendor implementation determines
that an HTTP request needs to be delivered to a method of one of these classes, an instance
of it will be created for the duration of the request and thrown away. You are delegating the
creation of these objects to the JAX-RS runtime.

The getSingletons() method returns a list of JAX-RS service objects (and providers,
too—again, see Chapter 6 ). You, as the application programmer, are responsible for creating
and initializing these objects.

These two methods tell the JAX-RS vendor which services you want deployed. Here's an ex-
ample: