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Re: AW: [jwt-dev] Extending the JWT Editor with Extension Points?
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Ralph, Florian, it seems things have been moving forward on your side,
that's great.
Ralph, your idea of using Eclipse plugins to extend the JWT workflow
metamodel is a good one and very "eclipse-like", I like it ! (See next mail)
Florian, I was thinking about that :
1. Dynamic EMF
Thank to your tipping me with the "dynamic emf" keyword, I found the
following :
http://www.ibm.com/developerworks/library/os-eclipse-dynamicemf/ .
* "particularly interesting in scenarios where part of the
application model code is generated through the EMF code generator, and
the rest of the model code is built using Dynamic EMF" :)
* basically, it uses EMF through its reflection API, and not
databound generated classes. This (I think) makes it not ideal for
extending the JWT graph editor, though it is perfect to store and
retrieve typed extensions (properties...) in a unified manner.
* NB. I believe the type extension can be loaded from an EMF XSD and
therefore doesn't require to be coded in java.
So it would be possible
* on one side for JWT developers to do "full", development-heavy
extensions that extend the core metamodel and require code generation,
* and on the other side to extend JWT in a costless manner ex. by
creating domain-specific tasks using only an EMF XSD describing the
typed extensions (we could even provide simple samples) and a property
page UI.
2. The hard part of dynamic EMF : knowing the extension XSDs
In the XML version of an EMF model, type extensions are written down as
XSD schemaLocation. So the hardest part (besides actually using the
extended model through the slightly cumbersome - compared to databound
classes - EMF reflection API) is to provide a nice enough way to find
and manage them. Here are a few ideas :
* by default, trying to find the type using the schemaLocation XML
header, as an absolute path or relative to the same directory as the
workflow XML (or if schemaLocation is not enough, maybe define a
workflow property ?)
* else in a well defined "extensionRepository" directory of this JWT
installation
* that's another subject, but, what about defining another workflow
file type : a zip file containing one workflow process file and
extension type files ?
More in next mail
Regards,
Marc
Florian Lautenbacher a écrit :
Hi Ralph,
yes, we had a very lively discussion on Thursday about the different aspects
of workflow models and workflow engines. Thanks again for the warm welcome,
Ralph!
I agree with you that we should include a mechanism for any vendor to
include their specific information in the workflow model. This could be the
hooks of Bonita in XPDL, the JEE server data, etc. Probably that's also one
of the things Bryan and Marc are discussing in another thread. So the
generic properties we are currently implementing could be a first step.
What you suggest "use Eclipse extension points to extend the model" reminds
me of a presentation I heard at this year's EclipseCon, where the concept of
"Dynamic EMF" was described (I believe in the context of a tool named Skyway
Perspectives). I'm not familiar with that right now and will have to read
some more, but maybe anybody else reading this mail knows about this
technique?
Anyway I'm looking more into the way the IX Workflow API and Modeler work in
order to get a better understanding how we could bring both together.
Best regards,
Florian
-----Ursprüngliche Nachricht-----
Von: jwt-dev-bounces@xxxxxxxxxxx [mailto:jwt-dev-bounces@xxxxxxxxxxx] Im
Auftrag von Ralph Soika
Gesendet: 18 April 2008 11:27
An: Java Workflow Toolbox
Betreff: [jwt-dev] Extending the JWT Editor with Extension Points?
Hi,
I want to make a suggestion of how to extend the JWT Modeler with vendor
specific extensions.
We talk yesterday to Florian Lautenbacher and Bernhard Bauer and discuss the
possibility that we from Imixs use the JWT Editor in future to model
Workflow Models for our "Imixs IX JEE Workflow Engine".
The general requirement for us is that we need to model a lot of individual
Informations/Attributes to each Activity inside the model.
For example our engine supports a "IX Mail Module" which needs informations
to generate a email during a transition.
So now what I want to suggest is: Why not to use the concept of Eclipse
extension points to extend the JWT Model itself?
My idea is that a vendor should not only be able to use a predefined
extension point inside the JWT Editor to add additional property pages to an
activity object. But also a vendor can describe an individual model
extensions using the same mechanism as used by eclipse to extend a plugin.
So for example, if we form Imixs like to extend the JWT Editor with an
additional property tab to describe the informations for our "IX Mail
Module" we also add an XSD File to describe the structure of the data.
The XSD File can be very similar to the XSD Files generated with the Eclipse
Plugin IDE. In fact JWT can use the existing Eclipse XSD Editor concept for
this.
In the end the JWT Editor extends the model xml file itself with the
additional structure for an activity as described in this XSD File or
creates an additional separate Model File. The informations are provided by
a property page from vendor specific plugin. Later on the IX Workflow Engine
can parse the JWT Model file for specific extensions like the "IX Mail
Extension".
Another aspect of this concept is hat a user of the JWT Editor can switch on
and off the extensions during modeling. So I can see and model using the
Imixs extensions and in the next moment I switch off this extension and can
see the natural model. Than I can switch on a extension from another vendor
to see other aspects of the same model.
This could be also a way to implement real round-trip-modelling.
What did you think about this?
best regards
ralph
