Calls

The calls in the MQI can be grouped as follows:

MQCONN, MQCONNX, and MQDISC
Use these calls to connect a program to (with or without options), and disconnect a program from, a queue manager. If you write CICS programs for z/OS, you do not need to use these calls. However, you are recommended to use them if you want to port your application to other platforms.
MQOPEN and MQCLOSE
Use these calls to open and close an object, such as a queue.
MQPUT and MQPUT1
Use these calls to put a message on a queue.
MQGET
Use this call to browse messages on a queue, or to remove messages from a queue.
MQINQ
Use this call to inquire about the attributes of an object.
MQSET
Use this call to set some of the attributes of a queue. You cannot set the attributes of other types of object.
MQBEGIN, MQCMIT, and MQBACK
Use these calls when WebSphere MQ is the coordinator of a unit of work. MQBEGIN starts the unit of work. MQCMIT and MQBACK end the unit of work, either committing or rolling back the updates made during the unit of work. i5/OS commitment controller is used to coordinate global units of work on i5/OS. Native start commitment control, commit, and rollback commands are used.

The MQI calls are described fully in the WebSphere MQ Application Programming Reference.