WebSphere Message Brokers
File: ac35400_
Writer: Catherine Tucker

Reference topic

This build: July 31, 2007 21:20:33

WebSphere MQ connections

The number of WebSphere MQ connections a broker requires to its queue manager depends on the actions of the message flows that access the MQ resource. For each broker flow that accesses a queue, one connection is required for every message flow thread. If a different node on the same thread uses the same queue manager, the same connection is used.

The number of queue handles required also depends on the behavior of the flow. For each flow that accesses queues, one queue handle is required for each unique queue name for every message flow thread. Nodes accessing the same queue name in the same flow use the same queue handle.

When you start a broker, and while it is running, it opens WebSphere MQ queue handles. The broker caches these queue handles. For example, when a message flow node initiates access to the first MQ resource it uses, it opens a connection for the queue manager and opens the queue. This is done the first time that a message is processed by that message flow node. For MQInput nodes this occurs when the flow is started. This queue handle remains open until:
  • The message flow becomes idle and has not been used for one minute
  • The execution group is stopped
  • The broker is stopped
The queue handle for the input node is not released when the flow is idle. The queue handle is released only when you stop the message flow.

A thread performing WebSphere MQ work becomes idle when it has not received any messages on its input queue for one minute. The allowed idle time starts from when the input queue being read becomes empty. If a message flow gets a message from the input queue, the timer is reset.

When a message flow is idle, the execution group periodically releases WebSphere MQ queue handles. Therefore, connections held by the broker reflect the broker's current use of these resources.

Related concepts
User database connections
Message flows overview
Related reference
Built-in nodes
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Copyright IBM Corporation 1999, 2007Copyright IBM Corporation 1999, 2007. All Rights Reserved.
This build: July 31, 2007 21:20:33

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