YAWL - User Manual - Polytechnic of Namibia - Mirrors

38 CHAPTER 3. GETTING STARTED WITH YAWLapproval amounts of less than $5000 are to be routed to the Small Credit Approval task. Anything morerequires Large Credit Approval to be run. The XPath expressions needed to capture this choice are shown inFigure 3.14. Once this is specified, we are done. We have a workflow specification that ensures the rightwork and data gets routed to the right participants at the right time.Figure 3.14: XPath predicates to choose between flows of an XOR-Split task3.5 Where To From HereYou’ve now seen how we can construct a workflow specification for YAWL. We’ve used atomic tasks, withvarious types of splits and joins, along with resourcing and data requirements to implement a simple creditapplication processing workflow specification. But, we have so far only scratched the surface of what canbe achieved with YAWL.What you haven’t seen yet is how larger workflows can be constructed by binding a number of nets togetherwith composite tasks. We are also capable of iterating through a number of instances of a single task usingMultiple Instance Task constructs. A single task can also be used to trigger the cancellation of current workin other parts of the workflow, which might be used for modelling a customer calling and cancelling anorder that is currently being processed. Finally, we haven’t described conditions, which represent the statea workflow is in after one task is finished but before another starts. Conditions allow us to model twoor more participants competing for the same work, or a user making a decision on things that workflow