Compatibility between different versions of an IBM MQ MQI client and a queue manager

The compatibility between clients and queue managers applies only to the version and release (V.R) of the product. The statement of compatibility does not necessarily apply to the modification and fix pack level (M.F) of the product.

If there are known problems at a specific V.R.M.F of the product, an upgrade to a more recent fix pack for the same Version.Release is necessary.

When you upgrade a queue manager to a different version, you automatically upgrade IBM MQ libraries. The libraries are used by IBM MQ MQI client and server applications running on the same server as the queue manager. To access new functions from remote clients, we must also upgrade the IBM MQ MQI client installation on remote workstations. The IBM MQ MQI client includes the IBM MQ MQI client libraries.

Remote clients that have not been upgraded continue to work with an upgraded queue manager. The behavior of the client application might, in rare cases change. We must consult Changes that affect migration, to find out whether changes in the current version affect your client applications.

Remote clients that are connected to upgraded queue managers can use the new functions in the release. If an upgraded remote client is connected to a queue manager that has not been upgraded, it must not use new functions. In rare cases, the behavior of the client might change; see Changes that affect migration.

We can generally assume that upgrading the IBM MQ MQI client does not require you to recompile or relink the client application. We can also continue to use the same connection to the queue manager. If changes are required, they are identified in Migrating a queue manager on Windows, for the particular migration path and platform we are concerned with.

The Client Channel Definition Table (CCDT) is an interface to customize the connection between an IBM MQ Client and a queue manager. Entries in the tables are client connections, which are defined using a queue manager. The version of a CCDT is the version of the queue manager used to define the client connections. If an IBM MQ MQI client uses CCDT to connect to a queue manager, the CCDT can be at a version greater than, less than, or equal to that of the client.

We can connect to a queue manager with an earlier IBM MQ Client or an earlier CCDT. If we are using a CCDT, and we plan to use new client channel configuration options, such as shared conversations, we must upgrade the CCDT, and therefore the IBM MQ MQI client installation to the new version.

• MQI client: Client Channel Definition Table (CCDT)
  We can connect an IBM MQ MQI client application to any level of queue manager. If a client uses CCDT to connect to a queue manager, the CCDT can be at a version greater than, less than, or equal to that of the client.
• MQI client: Client configuration stanzas moved into a new configuration file
  Client configuration information is moved from existing configuration stanzas into a new configuration file, mqclient.ini.
• MQI client: Default behavior of client-connection and server-connection channels
  In Version 7.0 the default settings for client and server connection channels changed to use shared conversations. This change affects the behavior of heartbeats and channels exits, and can have an impact on performance.
• MQI client: MQPUT1 sync point behavior change
  An MQPUT1 call by an IBM MQ MQI client application that failed in IBM WebSphere MQ Version 6.0 can now sometimes succeed. The failure is returned to the application later, if it calls MQCMIT. For the change in behavior to occur, the MQPUT1 must be in sync point.

Parent topic: Coexistence, compatibility, and interoperability