Adobe® Flex® 3 Bible

Chapter 25. Using the Message Service with BlazeDS

When Flex Data Services 2 was first released, one of its most compelling new features was known as the Flex Message Service.

This service allowed developers to create applications where data and information were shared instantly between multiple connected client applications, without having to program with low-level socket-style APIs.

With the renaming of Flex Data Services as Live Cycle Data Services, this server-based function became known simply as the Message Service (or, when referred to in the context of BlazeDS, the BlazeDS Message Service). Using this service, Flex client applications send messages to a destination on the server; the server then distributes the messages to other connected clients over a supported communication protocol.

Live Cycle Data Services (referred to here simply as LCDS) supports Real Time Messaging Protocol (RTMP), a protocol that implements true server-push capability. When LCDS Message Service destinations use an RTMP channel, data is pushed from the server to connected clients instantly (or as close as possible given available network and server resources). BlazeDS, the free open-source implementation of LCDS features, doesn't include the RTMP protocol, but adds the ability to define long-polling and streaming channels based on HTTP that allow you to create a messaging architecture that's very close to real time.

In this chapter, I describe how to use the Flex framework and BlazeDS to create and deploy ...