Chapter 14. Building a Real-Time Messaging System


  • Understanding the application process

  • Writing the Java code

  • Writing the Flex code

  • Connecting the Java and Flex pieces

A real-time messaging system allows users to talk with one another in real time as though they were in the same room. This functionality can be used in such diverse applications as chat or instant messaging programs, customer support systems, and multiplayer games.

Understanding the Application Process

This simple chat application allows users to type a username to use during the chat or generates a random username for the user. Once the username has been typed, a note is sent saying that the user has entered the chat. The user types messages in a text input field. When the user clicks the Send button or presses the Enter key while the text input field has focus, the message is sent to the chat server. When the chat server receives the message, it publishes the message to all clients connected to the chat server.

The Flex client for this application consists of text input fields to type a username and the messages to be sent during the chat, a list control to display all the messages in the chat room, and buttons for saving the username and sending the chat message.

On the Java side, a single Java class acts as a message receiver and sender. It takes any messages it receives from a single chat client and broadcasts them to every chat client connected to the server.

This application uses BlazeDS as its messaging ...

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