In this video we introduce the IEEE standard for process logs called EXtensible Event Streams (XES). XES files can be directly exported from YAWL. Whereas with other IT systems it may take several days to get an activity file for process mining, in YAWL this is a matter of minutes. The zip file below contains the YAWL specification to create your own XES file and the XES file that we have produced for this tutorial.
Welcome to our second tutorial on process mining with YAWL! So in the last tutorial, we covered some basics of process mining and this time, we are talking about XES. XES stands for eXtensible Event Stream and is an IEEE standard for process mining. XES is based on XML. So what are process logs? In XES a process log consists of several traces. And a trace corresponds to a case in YAWL. So in a log there are several cases that are protocolled. Then in each trace, we have events. And each event corresponds to a work item that has been executed. And there can be several events for each of the work items. And in the graphics behind me you can see the schema of XES. And you can see the logs, the traces, and the events. And you can also see the attributes and also that XES is in fact extensible. On the next slide you can see the states that can be logged in the XES standard. So you can see something is started, something is running, or suspended. Something can successfully complete or can fail. All these things are possible. On the next slide you can see the YAWL system with its different components. The engine, the resource service, and the worklet service, and many other components. What you can also see is that there are several places where YAWL is logging. So first the engine is producing some log information but for example, the engine doesn't know about the resources. All the knowledge about the resources are in the resource service. So if we want to see who has executed a work item, we have to look in the log of the resource service. And last but not least, the worklet service has its own log again. And so for producing an XES file with all the log information, there is some logic in YAWL going on that is collecting all of these logs of these three sources and puts them all into one XES file. On the next slide you can see the life cycle of a your work item. Work items in YAWL are first offered, then they can be allocated, then started, and finally completed.
And this life cycle of the YAWL work item closely corresponds to what we have in the XES state chart that I showed you before. And this is not a coincidence. So when we do process mining with YAWL XES files, we can discover lots of information about when did work items start, when were they completed, and we can for example measure the time it has taken for someone to fill in a form. And of course, we can also concentrate on certain events like fail events or complete events and ignore the difference between start and completion. So there are many possibilities here. So in order to demonstrate process mining with YAWL, we will take a specification from tutorial 12, where it was about developing or buying software. And this specification is the basis for our process log now. In the matrix behind me, you can see the eight cases that we have produced for demonstrating process mining with YAWL. So you can see that there are differences between make or buy, develop or procure software. There are also differences in the budget and also if there has been an approval or not. And all these cases are listed here. And these are the cases that go into our log file at the end. After we have finished all of our cases, we go to the control center as the YAWL administrator and select the specification and then click download log. And the result of this is an XES file. And you can find the XES file in the supplementary material. Feel free to also produce your own XES file and do experiments with that. So either with your XES file or with the one from the supplementary material, we will go to the next video and I'll explain you how to handle this XES file in ProM. See you then!