Specifying the Keep-Alive Mode for the Broker Connection

The keep-alive mode indicates whether the Broker checks for dropped connections from a client and then explicitly disconnects the client if it has dropped the connection. By disconnecting the client, the Broker makes any unacknowledged documents retrieved by that client available for redelivery to other clients.

If client state is not shared, an undetected broken connection does not pose a problem. The Broker will automatically redeliver unacknowledged events to the client when it reconnects. However, if the client state is shared and a client loses its connection to the Broker, the client cannot retrieve the unacknowledged documents after it re-establishes the connection. (The default client for the Integration Server and all trigger clients are shared-state clients.) This is because the same client ID is used by all the clients in a shared-state client. The Broker cannot distinguish the reconnection of one client from the ordinary reconnections of other clients with the same client ID. The unacknowledged documents retrieved by the now disconnected client will not be made available for redelivery until the Broker receives an explicit disconnect notice (generally, when the TCP/IP connection finally times out). In some cases, this might be hours later.

To avoid a situation in which unacknowledged documents stay on the Broker for an unacceptable period of time, you can select a keep-alive mode that will disconnect unresponsive clients and make unacknowledged documents available for redelivery.

You can configure one of the following keep-alive modes:

Normal. The Broker sends a keep-alive message to the Integration Server at a specified time interval (keep-alive period) and expects a response within another specified time interval (max response time). If the Broker does not receive a response, it will retry up to the number of times specified by the retry count. If the Integration Server still does not respond to the keep-alive message, the Broker explicitly disconnects the Integration Server. Normal is the default mode.

For example, by default, the Broker sends the Integration Server a keep-alive message every 60 seconds. If the Integration Server does not respond within 60 seconds, the Broker sends up to three more keep-alive messages before disconnecting the Integration Server. (The default retry count is 3.)

Listen Only. The Broker disconnects the Integration Server if there is no activity from the Integration Server over a specified time interval (keep-alive period). In listen only mode, the Broker does not send keep-alive messages to the Integration Server and ignores the retry count.

For example, suppose that the Broker expects activity from the Integration Server every 60 seconds. If there is no activity from the Broker after 60 seconds, the Broker disconnects the Integration Server.

Disabled.The Broker disables keep-alive interaction with this Integration Server. The Broker does not send keep-alive messages and does not disconnect the Integration Server because of inactivity.