Usage notes

1. The queue manager to which connection is made using the MQCONN call is called the local queue manager.

2. Queues that are owned by the local queue manager appear to the application as local queues. It is possible to put messages on and get messages from these queues.

   Shared queues that are owned by the queue-sharing group to which the local queue manager belongs appear to the application as local queues. It is possible to put messages on and get messages from these queues.

   Queues that are owned by remote queue managers appear as remote queues. It is possible to put messages on these queues, but not possible to get messages from these queues.

3. If the queue manager fails while an application is running, the application must issue the MQCONN call again in order to obtain a new connection handle to use on subsequent MQ calls. The application can issue the MQCONN call periodically until the call succeeds.

   If an application is not sure whether it is connected to the queue manager, the application can safely issue an MQCONN call in order to obtain a connection handle. If the application is already connected, the handle returned is the same as that returned by the previous MQCONN call, but with completion code CCWARN and reason code RC2002.

4. When the application has finished using MQ calls, the application should use the MQDISC call to disconnect from the queue manager.

5. On i5/OS, applications written for releases prior to MQSeries V5.1 of the queue manager can run without the need for recompilation.

6. This is a compatibility mode. This mode of operation provides a compatible run-time environment for applications written using the dynamic linkage . It comprises the following:

   • The service program AMQZSTUB residing in the library QMQM.

     AMQZSTUB provides the same public interface as previous releases, and has the same signature. This service program can be used to access the MQI through bound procedure calls.

   • The program QMQM residing in the library QMQM.

     QMQM provides a means of accessing the MQI through dynamic program calls.

   • Programs MQCLOSE, MQCONN, MQDISC, MQGET, MQINQ, MQOPEN, MQPUT, MQPUT1, and MQSET residing in the library QMQM.

     These programs also provide a means of accessing the MQI through dynamic program calls, but with a parameter list that corresponds to the standard descriptions of the MQ calls.

   These three interfaces do not include capabilities that were introduced in version 5.1. For example, the MQBACK, MQCMIT, and MQCONNX calls are not supported. The support provided by these interfaces is for single-threaded applications only.

   Support for the static bound MQ calls in single-threaded applications, and for all MQ calls in multi-threaded applications, is provided through the service programs LIBMQM and LIBMQM_R respectively.

7. On i5/OS, programs that end abnormally are not automatically disconnected from the queue manager. Therefore applications should be written to allow for the possibility of the MQCONN or MQCONNX call returning completion code CCWARN and reason code RC2002. The connection handle returned in this situation can be used as normal.