WM154G IBM MQ V9 System Administration

A key impediment to a flexible enterprise is traditional application connectivity, which combines business applications with one of many network application programming interfaces (API). This architecture requires knowledge of the networking conditions to adequately handle any communication problems.

With messaging-oriented middleware, such as IBM MQ, all the work of connecting, polling, handling failure, and implementing change is removed from the application. Instead, message-oriented middleware provides a dedicated middleware layer for handling connectivity. It is decoupled from the sending and receiving application, which provides the flexibility to react to business conditions.

IBM MQ creates a distributed communications layer that insulates the application developer from the details of the various operating systems and network interfaces. So, application modules can be distributed over heterogeneous operating systems.

In IBM MQ, data is packaged in messages, which are stored on queues. Queues allow programs to put and get messages as required so that programs can run independently of each other, at different speeds and times, and in different locations.

IBM MQ supports asynchronous calls between the client and server applications.

MQ supports two message-queuing styles: point-to-point and publish/subscribe.

In point-to-point messaging, a sending application must know information about the receiving application before it can send a message to that application. For example, the sending application might need to know the name of the queue to which to send the information, and might also specify a queue manager name. The point-to-point messaging style requires connections across all queue managers that need to get or put the message.

In publish/subscribe messaging, a copy of each message that is published by a publishing application is delivered to every interested application. There might be many, one, or no interested applications. In publish/subscribe, an interested application is known as a subscriber and the messages are queued on a queue that is identified by a subscription.

With publish/subscribe messaging, you can decouple the provider of information from the consumers of that information. The sending application and receiving application do not need to know as much about each other for the information to be sent and received.

In this unit, you learn about the point-to-point messaging style.

A cluster is a collection of queue managers that can be on different servers and operating systems, and typically serve a common application.

Every queue manager can make the queues that it hosts available to every other queue manager in the cluster, without the need for (remote) queue definitions. Cluster-specific objects also remove the need for explicit channel definitions and transmission queues for each destination queue manager.

The queue managers in a cluster often assume the role of a client or a server. The servers host the queues that are available to the members of the cluster and applications that process these messages and generate responses. The clients PUT messages to the server queues and might receive response messages.

Queue managers in a cluster normally communicate directly with each other, although typically, many of the client systems never need to communicate with other client systems.

Clustering was introduced in the prerequisite course WM103/ZM103, A Technical Introduction to IBM MQ.