Heartbeat interval (HBINT)
This attribute specifies the approximate time between heartbeat flows that are to be passed from a sending message channel agent (MCA) when there are no messages on the transmission queue.
Heartbeat flows unblock the receiving MCA, which is waiting for messages to arrive or for the disconnect interval to expire. When the receiving MCA is unblocked, it can disconnect the channel without waiting for the disconnect interval to expire. Heartbeat flows also free any storage buffers that have been allocated for large messages and close any queues that have been left open at the receiving end of the channel.
The value is in seconds and must be in the range 0 - 999 999. A value of zero means that no heartbeat flows are to be sent. The default value is 300. To be most useful, the value must be significantly less than the disconnect interval value.
With applications that use IBM MQ classes for Java, JMS or .NET APIs, the HBINT value is determined in one of the following ways:
- Either by the value on the SVRCONN channel that is used by the application.
- Or by the value on the CLNTCONN channel, if the application has been configured to use a CCDT.
For server-connection and client-connection channels, heartbeats can flow from both the server side as well as the client side independently. If no data has been transferred across the channel for the heartbeat interval, the client-connection MQI agent sends a heartbeat flow and the server-connection MQI agent responds to it with another heartbeat flow. This happens irrespective of the state of the channel, for example, irrespective of whether it is inactive while making an API call, or is inactive waiting for client user input. The server-connection MQI agent is also capable of initiating a heartbeat to the client, again irrespective of the state of the channel. To prevent both server-connection and client-connection MQI agents heart beating to each other at the same time, the server heartbeat is flowed after no data has been transferred across the channel for the heartbeat interval plus 5 seconds.
For server-connection and client-connection channels working in the channel mode before IBM WebSphere MQ Version 7.0, heartbeats flow only when a server MCA is waiting for an MQGET command with the WAIT option specified, which it has issued on behalf of a client application.
For more information about making MQI channels work in the two modes, see SharingConversations (MQLONG).
Parent topic: Channel attributes in alphabetical order
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