Extending queue manager facilities

The facilities provided by a queue manager can be extended by:

• User exits
• Installable services

User exits

User exits provide a mechanism for you to insert your own code into a queue manager function. The user exits supported include:

Channel exits

These exits change the way that channels operate. Channel exits are described in WebSphere MQ Intercommunication.

Data conversion exits

These exits create source code fragments that can be put into application programs to convert data from one format to another. Data conversion exits are described in the WebSphere MQ Application Programming Guide.

The cluster workload exit

The function performed by this exit is defined by the provider of the exit. Call definition information is given in WebSphere MQ Queue Manager Clusters.

Installable services

Installable services are more extensive than exits in that they have formalized interfaces (an API) with multiple entry points.

An implementation of an installable service is called a service component. You can use the components supplied with the WebSphere MQ product, or you can write your own component to perform the functions that you require.

Currently, the following installable services are provided:

Authorization service

The authorization service allows you to build your own security facility.

The default service component that implements the service is the Object Authority Manager (OAM). By default, the OAM is active, and you do not have to do anything to configure it. You can use the authorization service interface to create other components to replace or augment the OAM. For more information about the OAM, see Chapter 10, WebSphere MQ security.

Name service

The name service enables applications to share queues by identifying remote queues as though they were local queues.

A default service component that implements the name service is provided with WebSphere MQ. It uses the Open Software Foundation (OSF) Distributed Computing Environment (DCE). You can also write your own name service component. You might want to do this if you do not have DCE installed, for example. By default, the name service is inactive.

API exits

API exits let you write code that changes the behavior of WebSphere MQ API calls, such as MQPUT and MQGET, and then insert that code immediately before or immediately after those calls. The insertion is automatic; the queue manager drives the exit code at the registered points. For more information about API exits, see Chapter 22, API exits and the WebSphere MQ Application Programming Guide.

See Part 7, WebSphere MQ installable services and the API exit for more information about the installable services.