2010/8/21 Thiébault Benoît <d...@artenum.com>: > Hi everyone, > > I'm starting using SCXML and there is something that I am not sure to > understand very well. In the previous applications I developed, I used an > event-driven architecture : my user interface (for instance) was triggering > Events that an EventDispatcher converted into (a) Action call(s). The mapping > Event/Action(s) was declared in a separate XML file. When I discovered SCXML > I thought I could improve this architecture by declaring the Event/Action(s) > mapping in the SCXML file. There are however some points that are not very > clear yet for me. > > In the State design pattern (http://en.wikipedia.org/wiki/State_pattern), a > state is represented by a class while the actions are mapped with the methods > (roughly). I though I could thus map my events with a method of a given > object. > > But when I look at the StopWatch use case, and especially the StopWatch class > (http://commons.apache.org/scxml/xref-test/org/apache/commons/scxml/env/StopWatch.html), > the whole state machine is represented by the class and each state is mapped > by the methods... In this use case, I don't see how actions are handled. > > I mean if I have two events triggered targeting the same state, how can I > handle both events differently ? There could be two ways to go from a state A > to a state B, for instance in an application where you want to edit a text > file, from the "ready" state (when the application is ready to start) you > could go to the "edit" state by opening an existing file or by creating a new > one. The targeted state is then the same, even though the way to reach it is > different. I don't know how to model this in SCXML. > > Can someone help ? > <snip/>
The AbstractStateMachine class is one simple pattern among many that may be employed to use Commons SCXML [1], and is certainly very basic. It does not implement the State pattern as described in the document you point to. The State pattern itself has limitations (requiring a flattened state machine), so even implementing that isn't a silver bullet. As someone who wants to use the State pattern, please take a look at the AbstractStateMachine class implementation and perform the changes necessary to rather implement the State pattern instead. The higher order bit is that SCXML as a language is more powerful that any of these individual patterns. -Rahul [1] http://commons.apache.org/scxml/guide/using-commons-scxml.html > Thank you > Ben > > --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@commons.apache.org For additional commands, e-mail: user-h...@commons.apache.org
