MR01: Creating a HA Link between WebSphere MQ and a Service Integration Bus
This SupportPac enables a WebSphere MQ queue manager to connect with a WebSphere Application Server messaging engine (ME) via a MQ link in a highly available manner.
Currently the connection from a queue manager to a ME/MQ link is configured via the CONNAME field on a WebSphere MQ sender channel. This attribute references a single hostname and port number where the ME/MQ link is expected to listen; this is also known as an endpoint. However in a clustered WebSphere Application Server environment the target ME can failover from one server to another within the cluster and may be listening on any one of a number of different endpoints. As an example consider the following scenario:
A ME/MQ link running in a WebSphere Application Server cluster is listening at the location specified in the CONNAME field of a sender channel and is consuming messages being sent over that channel from WebSphere MQ. The machine that the ME/MQ link is running on suffers a hardware failure and crashes. The ME/MQ link is failed over to a separate machine running an Application Server that is part of the same WebSphere Application Server cluster and is again ready to consume messages. However WebSphere MQ will only deliver messages to the location specified in the CONNAME field, so messages remain on the appropriate WebSphere MQ transmission queue until the ME/MQ link is again listening at the endpoint specified by the CONNAME field and they can be delivered.
This SupportPac provides a simple channel message exit (referred to as 'the Exit' for the rest of this document), which will cycle through a list of possible CONNAME values, copying each one into the channel definition in turn until a connection between the queue manager and the target ME is made. Each time the connection fails the channel will retry and the Exit will select a new potential CONNAME value. The Exit is written in the C (for distributed platforms) and Assembler (for the z/OS platform) programming languages and is provided in source code format only and can be modified (depending on requirements) and installed on the desired platform.
The Exit requires a configuration file (dataset on the z/OS platform) which contains a list of possible CONNAME values and an index into this list indicating the value to be selected the next time the Exit is driven. This file can be created by hand, however included in this SupportPac is a Jython script file which can be used to query the configuration of a WebSphere Application Server cluster and generate a configuration file appropriately. On the z/OS platform, the script writes the configuration data into a hierarchical file system (HFS) file and this data will need to be copied into a sequential dataset. For more information on generating a configuration file see the Configuration section below. The configuration file location is passed to the Exit by entering its full path (for distributed platforms) or DDNAME (for the z/OS platform) in the MSGDATA field of the channel definition.
Customers wishing to have automatic functionality to establish the CONNAME value for a connection from a WebSphere MQ Queue Manager to a WebSphere Application Server ME should consider using this SupportPac.
SKILL LEVEL REQUIRED
The user requires knowledge of installing and compiling channel exits written in the C programming language (for distributed systems) or Assembler (for z/OS) in order to use this SupportPac.
NEW IN THIS RELEASE
• Support for the z/OS operating system.
Author: Matthew Leming and Mayur Raja, WebSphere Platform Messaging Development, Hursley, UK
Last updated: 18Dec06
Current Version: 1.0.1
»Please note that the version number shown in the right-hand pane is the version of the MQ or WBI product that this SupportPac applies to. The date is the last webpage refresh.
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This SupportPac requires:
WebSphere MQ v5.3 or v6 Server and
WebSphere Application Server v6 or above
The Exit provided by this SupportPac has been tested on the following platforms and WebSphere MQ releases at the latest Fix Pack levels:
HP NSK v5.3
Windows; AIX; iSeries v5.3 and v6.0
Linux RedHat v6.0
However, any operating system which is supported by WebSphere MQ versions 5.3 and 6.0 can be used.
1. Copy mr01.zip to a temporary directory.
2. Unzip the mr01.zip file. This will extract the necessary files.
3. Follow the instructions in the readme.txt file to compile and install the Exit code and understand how to use this SupportPac. The readme file uses ASCII encoding with UNIX line format. This should be taken into account when reading it.
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Category 2 SupportPacs are provided in good faith and AS-IS. There is no warranty or further service implied or committed and any supplied sample code is not supported via IBM product service channels.
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Please read the license information contained within the zip file of this SupportPac to determine if you want to use it.