Configuring MQ on iSeries
Computing professionals know about hardware and software. Another "ware" term, "middleware," is important when discussing systems integration. I define middleware as the tools needed to connect disparate systems.
Middleware is software that manages several parts of a connection between systems-the physical and logical communications, data translation, error recovery, message sequencing and so on. A programmer can put all of these pieces together, perhaps with socket programming or some client/server technique. I've done this many times and written several articles on the topic, but a product that can handle some of the details is often helpful.
This is where IBM's WebSphere* MQ (formerly MQSeries*) comes into play. (I'll be using the term MQ to refer to these software products from IBM.) More MQ information is available online.) MQ is used for applications between systems where the connectivity and assured delivery of messages is critical (e.g., moving information between banking and financial institutions).
MQ is used for time-independent, message-driven applications. Unlike socket programming, where a server must be running and listening in order for a client to connect, MQ can send a message to another system even if the other system isn't ready to receive it. For instance, the systems application or entire system or network could be down.
This article provides an overview of MQ configuration on iSeries, describes its components and shows RPG code samples for an iSeries implementation of MQ. While this article doesn't show all of MQs flexibility and power, it presents an example of how MQ can be used.
Overview of MQ Components
MQ uses four main components-messages, queues, queue managers and channels. (More information regarding MQ components can be found in the article"Family Portrait.") It's important to note that this isn't a complete list of MQ components; others are available for different MQ configurations.
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