The WebSphere MQ Adapter requires the com.ibm.mqetclient.jar file for XA transactions in Client mode and for deploying EAR files to a WebLogic application server. The JAR file is installed as part of the WebSphere MQ Extended Transaction client installation. Both the com.ibm.mq.jar and the com.ibm.mqetclient.jar must be added to the Integration Server classpath to run XA transactions in Client mode.