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Pre-Conditions for event handlers in workflow management systems Disclosure Number: IPCOM000021344D
Original Publication Date: 2004-Jan-16
Included in the Prior Art Database: 2004-Jan-16
Document File: 2 page(s) / 42K

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Event handlers, as specified for example in the Business Process Execution Language for Web Services standard proposal (see the appropriate OASIS TC homepage), provide for the processing of sets of activities parallel to the main part of a business process managed by a workflow management system.Event handlers are associated with scopes or the whole process. They are activated when the process navigates into the scope with which the event handler is associated and are de-activated when the process is ready to navigate out of the scope. An activated event handler is started when an appropriate message is sent to the process or a timer goes. In many cases however, the event handler should only be started if the activating message contains certain values. It is proposed to add pre-condition expressions to event handlers to handle this situation.

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Pre-Conditions for event handlers in workflow management systems

Workflow management systems support the definition and execution of business processes. A detailed description of such a system and its capabilities can be found in the book authored by F. Leymann and Dieter Roller, Production Workflow: Concepts and Techniques, Prentice Hall, 2000. Description of business processes is done either by some graphical end user interface or more importantly by some language. The purpose of the language is to define precisely all functions that can be used when describing business processes. One of these functions that can be defined for a business process are event handlers. Event handlers are either associated with a set of activities, usually called a scope or a sphere or with the whole process. An event handler is activated when navigation through the process enters the scope or in the case of an event handler attached to the process, when the process is started. Event handlers are instantiated as the result of an external message or the triggering of a timer. The body of an event handler consists of a set of activities that are carried out when the event handler is instantiated. In many cases, however, it is desirable to have an event handler only activated if the activating message contains certain values, the process/scope is in a certain state, or some variables within the process/scope have some value. This situation can be handled by checking for these conditions within the event handler body and terminating the event handler when appropriate. A much more efficient solution is provided by the introduction of pre-conditions (or activation conditions) for event handlers.

    The Business Process Execution Language for Web Services (BPELWS), jointly authored by BEA, Microsoft*, IBM**, and Siebel and submitted by the companies to OASIS for standardization, is such a language for defining business processes. Explanation in this disclosure are made in terms of BPEL4WS constructs. However this is for illustration purpose only; any other method for describing business processes including other languages can be substituted for explaining the concept of termination conditions for event handlers.

    Event handlers are specified in BPEL4WS via the eventHandlers el...