IBM GC34-5557-00 manual Message Queuing Time-Independent Applications, Message-Driven Processing

Message Queuing

Time-Independent Applications

With message queuing, the exchange of messages between the sending and receiving programs is time independent. This means that the sending and receiving applications are decoupled; the sender can continue processing without having to wait for the receiver to acknowledge receipt of the message. In fact, the target application does not even have to be running when the message is sent. It can retrieve the message when it starts running.

Message-Driven Processing

On arrival on a queue, messages can automatically start an application by using a technique known as triggering. If necessary, the application can be stopped when the message or messages have been processed.

Messages and Queues

Messages and queues are the basic components of a message queuing system.

What is a Message?

A message is a string of bytes that has meaning to the applications that use it. Messages are used to transfer information from one application to another (or to different parts of the same application). The applications can be running on the same platform, or on different platforms.

MQSeries messages have two parts; the application data and a message descriptor. The content and structure of the application data are defined by the application programs that use the data. The message descriptor identifies the message and contains control information, such as the type of message and the priority assigned to it by the sending application.

2MQSeries for AS/400, V5.1 Quick Beginnings