WebSphere MQ client

 

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Overview

WebSphere MQ clients can be installed separately from the MQ server.

The MQI is available to applications running on the client platform; the queues and other WebSphere MQ objects are held on a queue manager that you have installed on a server machine.

An application that you want to run in the WebSphere MQ client environment must first be linked with the relevant client library. When the application issues an MQI call, the WebSphere MQ client directs the request to a queue manager, where it is processed and from where a reply is sent back to the WebSphere MQ client.

The link between the application and the WebSphere MQ client is established dynamically at runtime.

WebSphere MQ client software is available at no charge from IBM Transaction Processing SupportPacs.

 

How the client connects to the server

An application running in the WebSphere MQ client environment runs in synchronous mode because there must be an active connection between the client and server machines.

The connection is made by an application issuing an MQCONN or MQCONNX call. Clients and servers communicate through MQI channels. When the call succeeds, the MQI channel remains connected until the application issues a MQDISC call. This is the case for every queue manager that an application needs to connect to.

 

Client and queue manager on the same machine

You can also run an application in the WebSphere MQ client environment when your machine also has a queue manager installed. In this situation, you have the choice of linking to the queue manager libraries or the client libraries, but remember that if you link to the client libraries, you still need to define the channel connections. This can be useful during the development phase of an application. You can test your program on your own machine, with no dependency on others, and be confident that it will still work when you move it to a full WebSphere MQ environment.

 

Clients on different platforms

Here is another example of a WebSphere MQ client and server system. In this example, the server machine communicates with three WebSphere MQ clients on different platforms.


Other more complex environments are possible. For example, a WebSphere MQ client can connect to more than one queue manager, or any number of queue managers connected as part of a queue-sharing group.

 

Why use WebSphere MQ clients?

Overview

Using WebSphere MQ clients is an efficient way of implementing WebSphere MQ messaging and queuing.

You can have an application that uses the MQI running on one machine and the queue manager running on a different machine (either physical or virtual). The benefits of doing this are:

  • There is no need for a full WebSphere MQ implementation on the client machine; for example, it could be a DOS, Windows 3.1, Windows 95, or Windows 98 system.

  • Hardware requirements on the client system are reduced.

  • System administration requirements are reduced.

  • a WebSphere MQ application running on a client can connect to multiple queue managers on different systems.

  • Alternative channels using different transmission protocols can be used.

 

What applications run on a WebSphere MQ client?

The full MQI is supported in the client environment. This enables almost any WebSphere MQ application to be relinked to run on a WebSphere MQ client by link the application on the WebSphere MQ client to the MQIC library, rather than to the MQI library. The exceptions are:

An application running on a WebSphere MQ client can connect to more than one queue manager concurrently, or use a queue manager name with an asterisk (*) on an MQCONN or MQCONNX call.

 

How do I set up a WebSphere MQ client?

To set up a WebSphere MQ client you need to have a WebSphere MQ server already installed and working on a machine, to which your client will connect. The steps involved in setting up a client are:

  1. Check that you have a suitable platform for a WebSphere MQ client and that the hardware and software satisfy the requirements.

  2. Install MQ client

  3. Ensure that your communication links are configured and connected.

  4. Check that your installation is working correctly.

  5. Configure security.

  6. Set up the channels between the WebSphere MQ client and server

    There are some additional considerations if you are using SSL. These are described in Chapter 9, The SSL on WebSphere MQ clients. You might need to use WebSphere MQ environment variables to set up the channels. These are described in Chapter 10, Using WebSphere MQ environment variables.

  7. WebSphere MQ applications are fully described in the WebSphere MQ Application Programming Guide.

 

WebSphere is a trademark of the IBM Corporation in the United States, other countries, or both.

 

IBM is a trademark of the IBM Corporation in the United States, other countries, or both.