MQ PCF commands

Overview

The purpose of WebSphere MQ programmable command format (PCF) commands is to allow administration tasks to be programmed into an administration program. In this way you can create queues, process definitions, channels, and namelists, and change queue managers, from a program.

PCF commands cover the same range of functions provided by MQSC commands. You can write a program to issue PCF commands to any queue manager in the network from a single node. In this way, you can both centralize and automate administration tasks.

Each PCF command is a data structure that is embedded in the application data part of a WebSphere MQ message. Each command is sent to the target queue manager using the MQI function MQPUT in the same way as any other message. The command server on the queue manager receiving the message interprets it as a command message and runs the command. To get the replies, the application issues an MQGET call and the reply data is returned in another data structure. The application can then process the reply and act accordingly.

Unlike MQSC commands, PCF commands and their replies are not in a text format that you can read.

Briefly, these are some of the things needed to create a PCF command message:

Message descriptor
This is a standard WebSphere MQ message descriptor, in which:

  • Message type (MsqType) is MQMT_REQUEST.
  • Message format (Format) is MQFMT_ADMIN.

Application data
Contains the PCF message including the PCF header, in which:

  • The PCF message type (Type) specifies MQCFT_COMMAND.
  • The command identifier specifies the command, for example, Change Queue (MQCMD_CHANGE_Q).

 

PCF object attributes

Object attributes in PCF are not limited to eight characters as they are for MQSC commands. They are shown in this book in italics. For example, the PCF equivalent of RQMNAME is Remotequeue_manager.

 

Escape PCFs

Escape PCFs are PCF commands that contain MQSC commands within the message text. You can use PCFs to send commands to a remote queue manager.

 

Using the MQAI

The MQAI is an administration interface to WebSphere MQ that is available on the AIX, HP-UX, Linux, Solaris, and Windows platforms.

It performs administration tasks on a queue manager through the use of data bags. Data bags allow you to handle properties (or parameters) of objects in a way that is easier than using PCFs. With MQAI, one does not have to write your own PCF messages, avoiding the problems associated with complex data structures.

To pass parameters in programs written using MQI calls, the PCF message must contain the command and details of the string or integer data. To do this, you need several statements in your program for every structure, and memory space must be allocated. This task can be long and laborious.

Programs written using the MQAI pass parameters into the appropriate data bag and you need only one statement for each structure. The use of MQAI data bags removes the need for you to handle arrays and allocate storage, and provides some degree of isolation from the details of the PCF.

MQAI can be used to implement self-administering applications and administration tools. For example, the Active Directory Services Interfaces provided by WebSphere MQ for Windows use the MQAI.

MQAI can be used to to handle error conditions more easily.

It is difficult to get return codes back from PCF commands, but the MQAI makes it easier for the program to handle error conditions.

After you have created and populated your data bag, you can send an administration command message to the command server of a queue manager, using the mqExecute call, which waits for any response messages. The mqExecute call handles the exchange with the command server and returns responses in a response bag.

 

Active Directory Services Interfaces

Active Directory Service Interfaces (ADSI) support allows client applications to use a common set of Component Object Model (COM) interfaces to communicate with, and control, any application that implements them.

Unlike tools written using other WebSphere MQ administration interfaces, those that use the ADSI are not limited to manipulating WebSphere MQ servers. The same tool can control Windows, Lotus Notes, or any application implementing the ADSI.

WebSphere MQ support for the ADSI is implemented through the use of the IBMMQSeries namespace.

Any programming language that supports the COM interfaces can be used to implement ADSI clients.

 

Client connection channels in the Active Directory

On Windows systems that support the Active Directory, WebSphere MQ publishes client connection channels in the Active Directory to provide dynamic client-server binding.

When CLNTCONN channels are defined, they are written into a binary file called AMQCLCHL.TAB. If the client channels use the TCP/IP protocol, the WebSphere MQ server also publishes them in the Active Directory. When the WebSphere MQ client determines how to connect to the server, it looks for a relevant CLNTCONN definition using the following search order:

  1. MQSERVER environment variable
  2. AMQCLCHL.TAB file
  3. Active Directory

This order means that any current applications are not affected by the change. You can think of these entries in the Active Directory as records in the AMQCLCHL.TAB file, and the WebSphere MQ client processes them in the same way. To configure and administer support for publishing client connection channel definitions in the Active Directory, use the setmqscp command.

 

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