WebSphere MQ for z/OS

 

With WebSphere MQ for z/OS we can write applications that:

• Use message queuing within CICS or IMS.

• Send messages between batch, CICS, and IMS applications, selecting the most appropriate environment for each function.

• Send messages to applications that run on other WebSphere MQ platforms.

• Process several messages together as a single unit of work that can be committed or backed out.

• Send messages to, and interact with, IMS™ applications by means of the IMS bridge.

• Participate in units of work coordinated by RRS.

Each environment within z/OS has its own characteristics, advantages, and disadvantages. The advantage of WebSphere MQ for z/OS is that applications are not tied to any one environment, but can be distributed to take advantage of the benefits of each environment. For example, we can develop end-user interfaces using TSO or CICS, we can run processing-intensive modules in z/OS batch, and you can run database applications in IMS or CICS. In all cases, the various parts of the application can communicate using messages and queues.

Designers of WebSphere MQ applications must be aware of the differences and limitations imposed by these environments. For example:

• WebSphere MQ provides facilities that allow intercommunication between queue managers (this is known as distributed queuing).

• Methods of committing and backing out changes differ between the batch and CICS environments.

• WebSphere MQ for z/OS provides support in the IMS environment for online message processing programs (MPPs), interactive fast path programs (IFPs), and batch message processing programs (BMPs). If you are writing batch DL/I programs, follow the guidance given in this book for z/OS batch programs.

• Although multiple instances of WebSphere MQ for z/OS can exist on a single z/OS system, a CICS region can connect to only one queue manager at a time. However, more than one CICS region can be connected to the same queue manager. In the IMS and z/OS batch environments, programs can connect to more than one queue manager.

• WebSphere MQ for z/OS allows local queues to be shared by a group of queue managers, giving improved throughput and availability. Such queues are called shared queues, and the queue managers form a queue-sharing group, which can process messages on the same shared queues. Batch applications can connect to one of several queue managers within a queue-sharing group by specifying the queue-sharing group name, instead of a particular queue manager name. This is known as group batch attach, or more simply group attach. See the WebSphere MQ for z/OS Concepts and Planning Guide for a full discussion of queue-sharing groups.

The differences between the supported environments, and their limitations, are discussed further in Using and writing applications on WebSphere MQ for z/OS.

 

Parent topic:

What can you do with WebSphere MQ products?

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