Examples for Chapter 13 - RESTful Java with JAX-RS 2.0 - page 325

GET /chat?current=1 /chat?current=1 HTTP HTTP / 1.1

Host : localhost:800

The next link's URI contains a query parameter identifying to the server the last message the
client read. The server will use this index to obtain the next message so that the client sees all
messages in order. This new GET request will either block again, or immediately return a
queued chat message. The pattern then repeats itself. The response will contain a new next
Link header with a new pointer into the message queue:

HTTP HTTP / 1.1 200 OOK

Content-Type : text/plain
Link : </chat?current=2>; rel=next

What's up?

The server will buffer the latest 10 chat messages in a linked list so that it can easily find the
next message a particular chat client needs. This is an example of a HATEOAS flow, where
the client transitions its state using a link passed back from the server.

The Client Code
The client is a console program that takes input from the command line while at the same
time printing out the current chat message. To run the client, you must specify the name you
want to use to post messages as an initial argument when you start up the program.

src/main/java/ChatClient.java

public public class class ChatClient ChatClient

{

public public static static void void main ( String [] args ) throws throws Exception

{

String name = args [ 0 ];

...
}

After grabbing the client's name from the argument list, we then initialize a Client that
we'll use to invoke on the customer chat service:

final final Client client = new new ResteasyClientBuilder ()

. connectionPoolSize ( 3 )
. build ();
WebTarget target = client . target ( "http://localhost:8080/services/chat" );