Chapter 12. Inquiring about and setting object attributes

Attributes are the properties that define the characteristics of a WebSphere MQ object. They affect the way that an object is processed by a queue manager. The attributes of each type of WebSphere MQ object are described in detail in WebSphere MQ Application Programming Reference.

Some attributes are set when the object is defined, and can be changed only by using the WebSphere MQ commands; an example of such an attribute is the default priority for messages put on a queue. Other attributes are affected by the operation of the queue manager and may change over time; an example is the current depth of a queue.

You can inquire about the current values of most attributes using the MQINQ call. The MQI also provides an MQSET call with which you can change some queue attributes. You cannot use the MQI calls to change the attributes of any other type of object; instead you must use:

For WebSphere MQ for z/OS: The ALTER operator commands (or the DEFINE commands with the REPLACE option), which are described in WebSphere MQ Script (MQSC) Command Reference.
For WebSphere MQ for iSeries: The CHGMQMx CL commands, which are described in WebSphere MQ for iSeries V5.3 System Administration, or you can use the MQSC facility.
For MQSeries for Compaq NonStop Kernel: The MQM screen-based interface, which is described in MQSeries for Compaq NonStop Kernel System Administration, or you can use the MQSC facility.
For MQSeries for VSE/ESA: The panel interface, which is described in MQSeries for VSE/ESA System Management Guide.
For WebSphere MQ for all other platforms: The MQSC facility, described in WebSphere MQ Script (MQSC) Command Reference.

Note:: The names of the attributes of objects are shown in this book in the form that you use them with the MQINQ and MQSET calls. When you use WebSphere MQ commands to define, alter, or display the attributes, you must identify the attributes using the keywords shown in the descriptions of the commands in the above books.

Both the MQINQ and the MQSET calls use arrays of selectors to identify those attributes you want to inquire about or set. There is a selector for each attribute you can work with. The selector name has a prefix, determined by the nature of the attribute:

MQCA_	These selectors refer to attributes that contain character data (for example, the name of a queue).
MQIA_	These selectors refer to attributes that contain either numeric values (such as `CurrentQueueDepth`, the number of messages on a queue) or a constant value (such as `SyncPoint`, whether or not the queue manager supports syncpoints).

Before you use the MQINQ or MQSET calls your application must be connected to the queue manager, and you must use the MQOPEN call to open the object for setting or inquiring about attributes. These operations are described in Chapter 7, Connecting and disconnecting a queue manager and Chapter 8, Opening and closing objects.