(1) In advanced program-to-program communications, the amount of processing that is started directly or indirectly by a program on the source system. See also unit of recovery.
(2) A recoverable sequence of operations performed by an application between two points of consistency. A unit of work begins when a transaction starts or at a user-requested syncpoint. It ends either at a user-requested syncpoint or at the end of a transaction.
(3) For IMS DB, all of the input and output messages associated with a transaction. For IMS TM, a single IMS message. For CQS, a client-defined grouping of data objects.
(4) A recoverable sequence of operations within an application process. At any time, an application process is a single UOW, but the life of an application process can involve many UOWs as a result of commit or rollback operations. In a multisite update operation, a single UOW can include several units of recovery. See also multisite update, unit of recovery, remote unit of work, transaction.