Reconnectable clients

IBM MQ clients can take advantage of automatic reconnection if their connection to a queue manager is broken. This is of value when a connection breaks, or a queue manager fails. When you stop a queue manager we have the option of enabling the automatic reconnection of clients.

There are a number of ways to code and configure a IBM MQ MQI client to make it continue to work if the queue manager to which it is connected fails. An application program can respond to a queue manager failure by closing queues and subscriptions and disconnecting from the failing queue manager. The client program might then attempt to reconnect, and either wait until the queue manager is running again, or connect to another queue manager in the same queue manager group.

To make this common procedure easier, a client program can connect to a queue manager with the option of being automatically reconnected to another queue manager (or reconnected to this queue manager) if the current connection fails. No application programming is required. The application program does not have to be notified of any broken connection errors from the queue manager.

Automatic client reconnection is not supported by IBM MQ classes for Java™.

As the IBM MQ administrator, you might want to signal to all client application programs, including ones that have requested queue manager failures to be handled automatically, that you are stopping the queue manager deliberately, and want client applications to stop, rather than have the client applications treat the queue manager stoppage as a failure and attempt to reconnect automatically. This is the default behavior of the Stop queue manager command, to maintain compatibility with earlier releases of IBM MQ. However, as an option on the Stop queue manager command, we can use the Instruct reconnectable clients to reconnect option, and the indication that the queue manager is stopping is intercepted by a reconnectable client connection, and it starts trying to reconnect automatically as if a failure had occurred.