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Fault Handlers for Event Handlers in Workflow Management Systems

IP.com Disclosure Number: IPCOM000026699D
Original Publication Date: 2004-Apr-06
Included in the Prior Art Database: 2004-Apr-06
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Abstract

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. When a fault occurs within an event handler, the scope or process is stopped and an appropriate fault is thrown. This is too restrictive in many cases; it is fairly sufficient to handle the fault within the event handler itself. It is proposed to add fault handlers to event handlers to handle this situation.

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Fault Handlers 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, called a scope 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. When a fault occurs, the scope or process is stopped, and an appropriate fault is thrown . This is too restrictive in many cases; it is fairly sufficient to handle the fault within an event handler itself. If the fault handler associated with the event handler determines that it can not handle the fault, it should rethrow the fault .

    The Business Process Execution Language for Web Services (BPEL4WS), 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 BPEL 4WS 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 fault handlers for event handlers .

    Event handlers are specified in BPEL4WS via the eventHandlers element as follows :

<scope>

<eventHandlers>

<onMessage>

<onAlarm>

</eventHandlers>

</scope>

    Event handlers that are activated via an external message are defined via the onMessage element; event handlers that are activated via a timer are defined via the onA...