Connecting to a queue manager using the MQCONN call
Use this information to learn how to connect to a queue manager using the MQCONN call.
- For IBM® WebSphere® MQ for z/OS®, in the batch environment, the default queue manager is specified in the CSQBDEFV module.
- For IBM WebSphere MQ for Windows, IBM i, UNIX, and Linux® systems, the default queue manager is specified in the mqs.ini file.
Alternatively, in the z/OS MVS™ batch, TSO, and RRS environments you can connect to any one queue manager within a queue-sharing group. The MQCONN or MQCONNX request selects any one of the active members of the group.
When you connect to a queue manager it must be local to the task. It must belong to the same system as the IBM WebSphere MQ application.
In the IMS environment, the queue manager must be connected to the IMS control region and to the dependent region that the program uses. The default queue manager is specified in the CSQQDEFV module when IBM WebSphere MQ for z/OS is installed.
With the TXSeries® CICS® environment, and TXSeries for Windows and AIX®, the queue manager must be defined as an XA resource to CICS.
To connect to the default queue manager, call MQCONN, specifying a name consisting entirely of blanks or starting with a null (X'00') character.
An application must be authorized for it to successfully connect to a queue manager. For more information, see Security.
The output from MQCONN is:
- A connection handle (Hconn)
- A completion code
- A reason code
Use the connection handle on subsequent MQI calls.
If the reason code indicates that the application is already connected to that queue manager, the connection handle that is returned is the same as the one that was returned when the application first connected. The application must not issue the MQDISC call in this situation because the calling application expects to remain connected.
The scope of the connection handle is the same as the scope of the object handle (see Opening objects using the MQOPEN call).
Descriptions of the parameters are given in the description of the MQCONN call in MQCONN.
The MQCONN call fails if the queue manager is in a quiescing state when you issue the call, or if the queue manager is shutting down.
Scope of MQCONN or MQCONNX
The scope of an MQCONN or MQCONNX call is typically the thread that issued it. That is, the connection handle returned from the call is valid only within the thread that issued the call. Only one call can be made at any one time using the handle. If it is used from a different thread, it is rejected as invalid. If you have multiple threads in your application and each wants to use IBM WebSphere MQ calls, each one must issue MQCONN or MQCONNX.
It is not necessary for each call to be made to the same queue manager when a process makes multiple MQCONN calls. However, only one WebSphere MQ connection can be made from a thread at a time. Alternatively, consider Shared (thread independent) connections with MQCONNX to allow multiple WebSphere MQ connections from a single thread and an WebSphere MQ connection to be used from any thread.1
If your application is running as a client, it can connect to more than one queue manager within a thread.