Simple One-On-One Chat with WebSocket Application

Overview

Modern web applications require more interactivity than ever before for client/server communications. HTTP, however, wasn't built to deliver the kind of interactivity needed today. "Push" or Comet techniques, such as long-polling, emerged as a way to allow a server to push data to a browser. Because these techniques usually rely on HTTP, they present some disadvantages for client/server communications, such as HTTP overhead. These disadvantages result in less efficient communication between the server and the web browser, especially for real-time applications.

WebSocket provides an alternative to this limitation by providing bi-directional, full-duplex, real-time, client/server communications. The server can send data to the client at any time. Because WebSocket runs over TCP, it also provides a low-latency, low-level communication and reduces the overhead of each message. WebSocket also provides greater scalability for message-intensive applications because only one connection per client is used (whereas HTTP creates one request per message).

The life cycle of a WebSocket is easy to understand as well:

• Client sends the Server a handshake request in the form of a HTTP upgrade header with data about the WebSocket it’s attempting to connect to.
• The Server responds to the request with another HTTP header, this is the last time a HTTP header gets used in the WebSocket connection. If the handshake was successful, they server sends a HTTP header telling the client it’s switching to the WebSocket protocol.
• Now a constant connection is opened and the client and server can send any number of messages to each other until the connection is closed. These messages only have about 2 bytes of overhead.

Build and Run :

• Run application :

    mvn clean tomcat7:run
  

• Call URL :

    http://localhost:8080/chat-websocket-application/
  

References

• [Java EE7 : Building Web Applications with WebSocket, JavaScript and HTML5] (http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/HomeWebsocket/WebsocketHome.html)
• [WebSockets – A Quick Introduction and a Sample Application] (https://blog.idrsolutions.com/2013/12/websockets-an-introduction/)