(C2) ;Verfahren zur Behebung von Systemausf穉llen in einem verteilten Computersystem und Vorrichtung zur Durchf穟hrung des Verfahrens

摘要

A work flow description database represents long running work flows as a set of steps 152 with information flows 154 therebetween. The database defines each step's input and output signals, input condition criteria for creating an instance of the step, an application program associated with the step, and criteria for selecting a resource-to execute the step. A work flow controller controls the process of executing instances of each defined type of work flow. During execution, each step is instantiated only when a sufficient set of input signals is received to execute that step. At that point an instance of the required type of step is created and then executed by a selected resource. After termination of a step, output signals from the step are converted into input event signals for other steps in the work flow in accordance with data stored in the database. Each step executes an application program and is treated as an individual transaction. Log records are durably stored upon instantiation, execution and termination of each step, and output event signals are also logged, thereby durably storing sufficient data to recover a work flow with virtually no loss of the work that was accomplished prior to a system failure. <IMAGE>