This topic applies only to the IBM Business Process Manager Advanced configuration.

Asynchronous reliability qualifiers

The three asynchronous reliability qualifiers (reliability, request expiration, and response expiration) determine the quality of the delivery of an asynchronous message.

You can specify, asynchronous reliability qualifiers for the reference to support asynchronous invocation of components. They only take effect when asynchronous programming calls are used by the client to invoke the service. The reliability, request expiration, and response expiration reference qualifiers are ignored by the runtime functions for synchronous interactions.

Reliability

The reliability qualifier determines the quality of the delivery of an asynchronous message. In general, better performance usually means less reliable message delivery.

Location: A reliability qualifier is set on a reference.

Settings: The reliability qualifier can have these settings:

Assured (persistent) - The client application cannot tolerate the loss of a request or response message.
Best effort (nonpersistent) - The client application can tolerate the possible loss of the request or response message.

In this context, persistent means saved to disk, so the request is recoverable if the server goes down before the target service is invoked, and nonpersistent means not saved to disk, so the request is lost if the server goes down before the target service is invoked.

Request expiration

Request expiration is the length of time, measured in milliseconds, after which an asynchronous request will be discarded if it has not been delivered, beginning from the time when the request is issued. A zero (0) denotes an indefinite expiration.

Location: A request expiration qualifier is set on a reference.

Response expiration

Response expiration is the length of time, measured in milliseconds, that the runtime environment must retain an asynchronous response or must provide a callback, beginning from the time when the request is issued. A zero (0) denotes an indefinite expiration.

Location: A response expiration qualifier is set on a reference.