Liberty and the IBM MQ resource adapter

The IBM MQ resource adapter can be installed into WebSphere Liberty Version 8.5.5, Fix Pack 2 or later, by using either the wmqJmsClient-1.1 or wmqJmsClient-2.0 feature, depending on which version of the resource adapter you are installing. Alternatively we can, subject to some restrictions, install the resource adapter by using generic Java Platform, Enterprise Edition Connector Architecture (Java EE JCA) support.

General restrictions when installing the resource adapter into Liberty

• The IBM MQ classes for Java are not supported in Liberty. They must not be used with either the IBM MQ Liberty messaging feature or with the generic JCA support. For more information, see Use WebSphere MQ Java Interfaces in J2EE/JEE Environments.
• The IBM MQ resource adapter has a transport type of BINDINGS_THEN_CLIENT. This transport type is not supported within the IBM MQ Liberty messaging feature.
• Before IBM MQ Version 9.0, the Advanced Message Security (AMS) feature was not included in the IBM MQ Liberty messaging feature. However, AMS is supported with an IBM MQ Version 9.0 or later resource adapter.

Restrictions when using the Liberty features

With Liberty Version 8.5.5, Fix Pack 2 to Version 8.5.5, Fix Pack 5 inclusive, only the wmqJmsClient-1.1 feature was available and only JMS 1.1 could be used. Liberty Version 8.5.5, Fix Pack 6 added the wmqJmsClient-2.0 feature so JMS 2.0 could be used.

• The IBM WebSphere MQ Version 7.5.0, Fix Pack 6 and later Version 7.5 resource adapter can be used with the wmqJmsClient-1.1 feature only.
• The IBM MQ Version 8.0.0, Fix Pack 3 and later Version 8.0 resource adapter can be used with wmqJmsClient-2.0 feature only.
• The IBM MQ Version 9.0 resource adapter can be used with wmqJmsClient-2.0 feature only.

Restrictions when using generic JCA support

• We must specify the level of JMS when using the generic JCA support:
  • JMS 1.1 and JCA 1.6 must be used only with the IBM WebSphere MQ Version 7.5.0, Fix Pack 6 and later Version 7.5 resource adapters.
  • JMS 2.0 and JCA 1.7 must be used only with the IBM MQ Version 8.0.0, Fix Pack 3 and later Version 8.0 resource adapters.

• It is not possible to run the IBM MQ resource adapter on z/OS using generic JCA support. In order to run the IBM MQ resource adapter on z/OS, it must be run with the wmqJmsClient-1.1 or wmqJmsClient-2.0 feature.
• Tracing, and logging are not integrated within the WebSphere Liberty trace system. Instead, the IBM MQ resource adapter trace must be enabled using either Java system properties, or an IBM MQ classes for JMS configuration file, as described in Tracing IBM MQ classes for JMS applications. For details about how to set Java system properties in WebSphere Liberty, see the WebSphere Liberty documentation.For example, in order to enable trace of the IBM MQ resource adapter in WebSphere Liberty 19.0.0.9, add the following entry to the WebSphere Liberty file jvm.options:

  -Dcom.ibm.msg.client.commonservices.trace.status=ON
  -Dcom.ibm.msg.client.commonservices.trace.outputName=C:\Trace\MQRA-WLP_%PID%.trc

  This results in trace being written to a trace file called MQRA-WLP_<process identifier>.trc in the directory C:\Trace.
• The location of the resource adapter is specified by using the following xml element:

  <resourceAdapter id="mqJms" location="${server.config.dir}/wmq.jmsra.rar">
    <classloader apiTypeVisibility="spec, ibm-api, api, third-party"/>        
  </resourceAdapter> 

  Important: The value of the ID tag can be anything EXCEPT for wmqJms. If you do use wmqJms as the ID, then Liberty is not able to properly load the resource adapter. This is because wmqJms is the ID that is used internally to refer to the specific feature for IBM MQ. It actually creates a NullPointerException. The following examples show some snippets from a server.xml file:

  <!-- Enable features -->    
    <featureManager>       
      <feature>servlet-3.1</feature>     
      <feature>jndi-1.0</feature>    
      <feature>jca-1.7</feature>      
      <feature>jms-2.0</feature>   
    </featureManager>

  Tip: Note the use of the jca-1.7 and jms-2.0 features and the lack of the wmqJmsClient-2.0 feature.

  <resourceAdapter id="mqJms" location="${server.config.dir}/wmq.jmsra.rar">
    <classloader apiTypeVisibility="spec, ibm-api, api, third-party"/>        
  </resourceAdapter> 

  Tip: Note the use of mqJms for the ID, which is preferred. Do not use wmqJms.

  <application id="WMQHTTP" location="${server.config.dir}/apps/WMQHTTP.war" 
  name="WMQHTTP" type="war">    
      <classloader apiTypeVisibility="spec, ibm-api, api, third-party" 
  classProviderRef="mqJms"/>    
  </application>

  Tip: Note the classloaderProviderRef back to the resource adapter through the id mqJms; this is to permit IBM MQ specific classes to be loaded.

Full Liberty XA support with client channel definition tables

When using WebSphere Liberty Version 18.0.0.2 onwards, with IBM MQ Version 9.2.0, we can make use of queue manager groups within the client channel definition table (CCDT) in conjunction with XA transactions. This means that it is now possible to make use of workload distribution and availability, provided by queue manager groups, whilst maintaining transaction integrity.

In the event of connectivity errors to a queue manager, the queue manager needs to become available again so that the transaction can be resolved. The transaction recovery is managed by Liberty, and you might need to configure the transaction manager, so that an appropriate period of time is allowed for the queue managers to become available again. For more information, see Transaction manager (transaction) in the WebSphere Liberty product documentation.

This is a client-side feature, that is, we need a Version 9.2.0 resource adapter, not a Version 9.2.0 queue manager.