Chapter 31, “Using the Message Service,” in the EAServer Programmer’s Guide describes EAServer messaging support. The EAServer message service supports the Java Message Service (JMS) 1.0.2 specification, which addresses the demands of distributed systems in a coherent manner. JMS offers an API and a set of semantics that prescribe the interface and general behavior of a messaging service.
The message service allows you to publish or send messages to a queue, where they are stored until they can be delivered to the queue’s recipient, which is either a client or a component. The message service provides a pull-style mechanism for client notification and a push-style mechanism for component notification. Clients can check their queue for new messages, or spawn a thread to wait for a message’s arrival. Components can also check for new messages and they can register to be notified when messages arrive in their queue.
The message service provides transient and persistent message storage for message consumers and allows message producers to send messages to a particular message queue, or to publish messages with specific topics, available to all message queues.
The message service is implemented as an EAServer component with interfaces specified in standard CORBA IDL. Consequently, it can be used by all types of clients and components.
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