Professional BlazeDS: Creating Rich Internet Applications with Flex® and Java®

2.3. Surveying the Configuration Options

Before you start using BlazeDS gainfully, you need to learn how to configure BlazeDS to work with your application.

Simply put, at the heart of BlazeDS is a Servlet that bootstraps the infrastructure that intercepts all calls between a Flex client and the BlazeDS instance. This Servlet, called MessageBrokerServlet, uses artifacts like channels, endpoints, and adapters to enable proxy, remoting, and messaging services. A default configuration file, called services-config.xml, which lies in the WEB-INF/flex folder of the BlazeDS installation, defines these artifacts and their relationships in the context of the MessageBrokerServlet. We will peek into this configuration file in this section and continue to revisit it in the later chapters in the context of BlazeDS's various services. However, nothing in the configuration will make much sense unless you first understand the fundamentals of channels, endpoints, and adapters.

Channels and endpoints connect a Flex client to a BlazeDS server. They are the primary components that enable communication between these two entities. Endpoints reside at the BlazeDS end. Flex clients use channels to connect to these endpoints.

The BlazeDS endpoints are Servlet-based endpoints. Each endpoint defines a type and format of communication. For example, endpoints exist for simple AMF data exchange, polling AMF, and AMF data streaming.

Analogously, the Flex client defines a set of channels that vary depending ...