The best effort pattern is useful for applications that produce a large number of messages in a short period and cannot provide information to the resequencer about the identifier to use for sequencing. Typically, the identifier used for sequencing in such scenarios is of a dateTime type or numeric type. Using the dateTime field as the sequence ID XPath enables you to control the sequencing. The messages are expected to be sent in sequence by the applications, thus the date and time the messages are sent can be used for sequencing. The Mediator makes the best effort to ensure that the messages are delivered in sequence.

The best effort resequencer can reorder messages based on no knowledge about the increment of the sequence ID. This situation means that unlike the standard resequencer, you do not need to define the increment of the sequence ID for the best effort resequencer in advance. When the messages are processed, they are processed in sequence based on the specified sequence ID and the messages that have arrived, whether a true sequence is received. The sequence IDs are either numeric or dateTime. Therefore, sequencing occurs on the numeric order or the dateTime order of the sequence IDs.