Overview of IBM MQ MQI clients

An IBM® MQ MQI client is a component of the IBM MQ product that can be installed on a system on which no queue manager runs.

Using an IBM MQ MQI client, an application running on the same system as the client can connect to a queue manager that is running on another system. The application can issue MQI calls to that queue manager. Such an application is called an IBM MQ MQI client application and the queue manager is called a server queue manager.

An IBM MQ MQI client application and a server queue manager communicate with each other by using an MQI channel. An MQI channel starts when the client application issues an MQCONN or MQCONNX call to connect to the queue manager and ends when the client application issues an MQDISC call to disconnect from the queue manager. The input parameters of an MQI call flow in one direction on an MQI channel and the output parameters flow in the opposite direction.

IBM MQ MQI client application running on a client communicating with a queue manager on a server. — Figure 1. Link between a client and server

The following platforms can be used. The combinations depend on which IBM MQ product you are using and are described in Platform support for IBM MQ clients.

IBM MQ MQI client	IBM MQ server
UNIX and Linux Windows IBM i HP Integrity NonStop Server	UNIX and Linux Windows IBM i z/OS® HP Integrity NonStop Server

The MQI is available to applications running on the client platform; the queues and other IBM MQ objects are held on a queue manager that you have installed on a server.

An application that you want to run in the IBM MQ MQI client environment must first be linked with the relevant client library. When the application issues an MQI call, the IBM MQ MQI client directs the request to a queue manager, where it is processed and from where a reply is sent back to the IBM MQ MQI client.

The link between the application and the IBM MQ MQI client is established dynamically at run time.

You can also develop client applications using the IBM MQ classes for .NET, IBM MQ classes for Java or IBM MQ classes for Java Message Service ( JMS ). You can use Java and JMS clients on [IBMi] IBM i, UNIX, Linux and Windows platforms. The use of Java and JMS is not described here. For full details on how to install, configure, and use IBM MQ classes for Java and IBM MQ classes for JMS see Using IBM MQ classes for Java and Using IBM MQ classes for JMS.