MQ

This is part of a series of small blog posts which will cover some of the smaller, perhaps less likely to be noticed, features of IBM MQ. Read other posts in this series.

MQ Client applications which run on machines where there is no queue manager are a common deployment. I'm sure you're all familiar with them. There are a number of different way to configure them from the simple MQSERVER environment variable to the full function CCDT. Depending on which mechanism you use, you end up setting a variety of different environment variables.

A simple client application might only need the MQSERVER environment variable.

set MQSERVER=SYSTEM.ADMIN.SVRCONN/TCP/win4.mqgem.com(1727)

A full function client using SSL/TLS might have several different ones set.

set MQCHLLIB=C:\MQGem
set MQCHLTAB=MQGEM.TAB
set MQSSLKEYR=C:\MQGem\key
set MQCERTLABL=MQGemClient
set MQSSLRESET=5000000

When deploying a change to a client application that requires some different environment variables to be set, it can be problematic to ensure that all the correct ones are set. What would be useful is if all these items could be put into one file and them when a change was required, a new copy of the file could be provided. Since the location of the file could be set up correctly when the application was first deployed, it wouldn't have to change, but the contents could be easily changed on subsequent deployments.

Well, you're in luck, since all the environment variables you see examples of above, and more, can alternatively be set in an mqclient.ini file.

The mqclient.ini file can be located in one of a number of different places, for example the working directory of the application - the full list of locations is detailed in Location of the client configuration file.

Here are the same requirements from above, showing what the contents of the mqclient.ini file would look like.

A simple client application might only need the ServerConnectionParms.

CHANNELS:
  ServerConnectionParms=SYSTEM.ADMIN.SVRCONN/TCP/win4.mqgem.com(1727)

A full function client using SSL/TLS might have several different settings.

CHANNELS:
  ChannelDefinitionDirectory=C:\MQGem
  ChannelDefinitionFile=MQGEM.TAB
SSL:
  SSLKeyRepository=C:\MQGem\key
  CertificateLabel=MQGemClient
  SSLKeyResetCount=500000

I've written about the mqclient.ini file before with a table of all the environment variables and their equivalent mqclient.ini file representations. Here's the table again, this time showing all mqclient.ini file attributes (not all of which have environment variables) and updated for IBM MQ V9. I've also included a column to show which things are also taken notice of by the Java and managed .Net clients (everything is used by the C Client, and thus the unmanaged .NET client); and a column showing any attributes that were introduced in V8 or V9, everything not otherwise noted is available in V7.0.0 and above which is when the mqclient.ini file was first introduced.

So, consider using an mqclient.ini file when deploying your next new client application and save yourself time in the future.

This table was written before the IBM Docs had an equivalent page. Rather than me trying to keep it up to date, please refer to Which IBM MQ clients can read each attribute for the most up-to-date version.

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