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Workflow programming. Graphical workflows. As discussed, WS-BPEL is an XML-based language for workflow programming However, it is verbose and clumsy so more readable graphical languages have been developed
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Graphical workflows • As discussed, WS-BPEL is an XML-based language for workflow programming • However, it is verbose and clumsy so more readable graphical languages have been developed • BPMN (Business Process Modelling Notation) has been proposed as a standard graphical workflow language
BPMN • Key concepts • Activities - things which are done as part of a workflow (rounded rectangle) • Events - something which happens that causes a change in the workflow (circle) • Gateways - a selection point (diamond) • Sequence flow - `Ordering relation. (solid arrow) • Message flow - exchange of information (dashed arrow) • Pool - a participant in a process (rectangle)
Programming a workflow • Think about activities and the end-to-end sequence to complete a process • Think about the participants in the process - each should be in a separate pool • Think about gateways (choices). What happens when an activity terminates abnormally. • Think about what information is exchanged by the activities involved
Workflow example • ADSL problem management in an ISP • Workflow involves interactions between • Customer and ISP • ISP and Telecomms company • Assume customer is having problems with their home broadband connection and is trying to get these fixed • Draw a graphical workflow showing activities and interactions between the customer, the ISP and the telecomms companies
Workflow information • You have to think about the activities involved in the workflow and ask me about what goes on • I will answer based on my recent experience of having a difficult problem fixed.