What Is Websphere MQ

WebSphere MQ is the leading messaging integration middleware product. Over more than 15 years WebSphere MQ or MQSeries has grown to provide flexible and reliable solutions that address the wide range of requirements.

A message queuing infrastructure built on WebSphere MQ technology provides an available, reliable, scalable, secure, and maintainable transport for messages with guaranteed once-only delivery.

Many enhancements have been added to WebSphere MQ during its evolution in the marketplace, including:

1. WebSphere MQ Clients: Enables an application to connect remotely or locally to a WebSphere MQ queue manager.

2. Publish/Subscribe: Increases messaging capability from point-to-point messaging to a less coupled style of messaging.

3. MQ Clusters: Allow multiple instances of the same service to be hosted through multiple queue managers, to enable load-balancing and fail-over and simplify administration.

4. Secure Sockets Layer support: SSL protocol can be used to secure communication between queue managers or MQ Client.

5. Diverse platforms: WebSphere MQ supports a wide range of operating system platforms.

Data is transferred between applications in messages. A message is a container consisting of two parts:

A. MQ Message Descriptor: Identifies the message and contains additional control information such as the type of message and the priority assigned to the message by the sending application.

B. Message data: Contains the application data. The structure of the data is defined by the application programs that use it, and MQ is largely unconcerned with its format or content.

The nodes within a WebSphere MQ message queuing infrastructure are called queue managers. The queue manager is responsible for accepting and delivering messages. Multiple queue managers can run on a single physical server or on a wide network of servers across a large variety of different hardware and operating system platforms.

Each queue manager provides facilities for reliable messaging using both point-to-point and Publish/Subscribe styles.

The queue manager maintains queues of all messages that are waiting to be processed or routed. Queue managers are tolerant of failures and maintain the integrity of business-critical data flowing through the message queuing infrastructure.

The queue managers within the infrastructure are connected via logical channels over a communications network. Messages automatically flow across these channels from the initial producer of a message to the eventual consumer of that message based on the configuration of the queue managers in the infrastructure. Changes can be made to the configuration of queues and channels, and this is transparent to the applications.

Asynchronous messaging

Two applications that must communicate, whether hosted on the same machine or separate machines, may have originally been designed to do so directly and synchronously. This was a common messaging technique used prior to the introduction of WebSphere MQ.

In this case the two applications exchange information by waiting for the partner application to become available and then sending the information. If the partner application is unavailable for any reason, including if it is busy performing communication with other applications, the information cannot be sent.

All intercommunication failures that can occur between the two applications must be considered individually by the applications, whether they are on the same machine or on different machines connected by a network. This requires a protocol for sending the information, confirming receipt of the information, and sending any subsequent reply.

Placing a WebSphere MQ infrastructure between the two applications allows this communication to become asynchronous. One application places information for the partner in a message on a WebSphere MQ queue, and the partner application processes this information when it is available to do so. If required, It can then send a reply message back to the originator. The applications do not need to be concerned with intercommunication failures or recovery.

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