Java Platform, Enterprise Edition (Java EE) 8 The Java EE Tutorial

## Path Parameters

The `ServerEndpoint` annotation enables you to use URI templates to specify parts of an endpoint deployment URI as application parameters. For example, consider this endpoint:

    @ServerEndpoint("/chatrooms/{room-name}")
    public class ChatEndpoint {
       ...
    }

If the endpoint is deployed inside a web application called `chatapp` at a local Java EE server in port 8080, clients can connect to the endpoint using any of the following URIs:

    http://localhost:8080/chatapp/chatrooms/currentnews
    http://localhost:8080/chatapp/chatrooms/music
    http://localhost:8080/chatapp/chatrooms/cars
    http://localhost:8080/chatapp/chatrooms/technology

Annotated endpoints can receive path parameters as arguments in methods annotated with `@OnOpen`, `@OnMessage`, and `@OnClose`. In this example, the endpoint uses the parameter in the `@OnOpen` method to determine which chat room the client wants to join:

    @ServerEndpoint("/chatrooms/{room-name}")
    public class ChatEndpoint {
       @OnOpen
       public void open(Session session,
                        EndpointConfig c,
                        @PathParam("room-name") String roomName) {
          // Add the client to the chat room of their choice ...
       }
    }

The path parameters used as arguments in these methods can be strings, primitive types, or the corresponding wrapper types.

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