Hello again! I´m not sure how to explain what I want to do. The task I have is to build an editor that you then can use to build simulations of applications. An application can be a cd-player for instance. What already exists is an editor for building GUI:s without coding (not build by me) and an engine that runs this and via a protocol "talks" to an application. What I´m trying to do is "attatch" my editor to the protocol instead of a "real life" application. The problem is that I´m developing this very generic. I can not know what kind of application the user want to simulate, the only thing I have to run this from is the protocol specification and in that specification it, for one thing, says that I should be able to handle dynamic data subscriptions.
In the cd-player case this could be that a track on the cd has ended and a new has begun, if I have an subscription for the title of the song playing I would then like to send it to the engine i was talking about. So if I write a datamodel like (well, I don´t, it would be generated like this): <data name=Data> <Title id=1 type=String>text</Title> <Track id=4 type=Integer>0</Track> </data> and then somewhere in the scema the person who build the simulation wants "title" to change, this is then translated to: <assign location="Data.title" expr="oh yeah!" /> as an example. If i want to "read" what data.title:s expression is, how do I do that? I used the: http://www.ling.gu.se/~lager/Labs/SCXML-Lab/ for more examples, I´m not sure if you´re using the same standard, but it´s an easy way to understand how the SCXML works. > This still is all quite vague to me -- for example, not clear where > you put the data in the first place. > > If you want to listen to data changes, listening to state changes may > not be the way to proceed (so I wouldn't use SCXMLListener for this > purpose). I can think of multiple potential options: > > * Avoid the need for any data synchronization / subscriptions > altogether - Back the state machine's root context with the actual > data store Unfortunently this is not an option because the parts that use the subscriptions are not written by me and already exists, I just want to "communicate" with these parts. > > > * Declaratively add <transition>s guarded on specific *.change events > - Has the benefit of capturing the associated actions in the SCXML > document itself (use the appropriate executable content on transition) Not sure how this would work for the user of my editor. > > > * Use a custom Context implementation - This will allow you to > intercept data changes, à la pointcut at > oacs.Context#set(String,Object), and get notifications that way This could possibly be of intrest, but I´m still not 100% sure on how the context works. Where would these notifications "arrive" best regards //Linda
