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JWT Metamodel

Introduction

This page describes the architecture, requirements and discussions for the meta-model of JWT. Starting from the original meta-model of AgilPro, it summarizes all evolutions, extensions, wishes etc.


Architecture

The JWT metamodel comprises

  • a core workflow metamodel that is as generic as possible
  • extensions that allow to provide specific additional features
  • overall governance that allows extensions to coexist within the JWT ecosystem.

Core metamodel

Its aim is to be a workflow metamodel that is as generic as possible.

Changes to the core metamodel should rather go in metamodel extensions, because they affect possibly all JWT users and must therefore be considered very carefully.

Metamodel extensions

Metamodel extensions allow to provide specific additional features, be it UI like JWT views, runtime like a WebServiceApplication or other features like logging.

  • Official JWT metamodel extensions : an official JWT metamodel extension is the standard for its domain model. To make your metamodel extension official, there must be none yet for its domain model, it must be approved by project leads and listed in JWT Metamodel Extensions/Official
  • JWT Labelized metamodel extensions : if there is already an official JWT extension for your domain model, you can make it JWT labelized by implementing a two-way transformation to an existing official or labelized metamodel extension along with its transformation documentation and test kit, make it approved by project leads and list it in JWT Metamodel Extensions/Labelized
  • extensions can obviously still be developed by anyone without being official or labelized, though their users can't be sure they'll be able to freely benefit from other parts of the JWT ecosystem, because of possible domain model specific incompatibility.

Metamodel governance

In order to become better and answer more user requirements, the JWT metamodel evolves. In order to avoid conflicts and compatibility problems, it does so in a governed manner, and with the help of tools such as an automated version converter.

Metamodel Roadmap

  • initial metamodel : JWT up to 0.5. This was originally AgilPro's metamodel.
  • core metamodel and aspect extensions : JWT 0.6 (upcoming). Includes core metamodel improvements and the new aspect extension mechanism.
  • externalized metamodel : later. The metamodel will be in its own plugin.


JWT up to 0.5 and AgilPro metamodel

Design

This document File:AgilPro MetamodelDescription.pdf describes the metamodel of AgilPro as it is today (2007-02-21). This document will be the basis for discussions on all working groups who have requirements on the meta-model.

JWT Metamodel Extension Specifications describes the specifications of the aspects metamodel extension mechanism


JWT up to 0.5 and AgilPro metamodel comparisons

Comparison with other metamodels

A comparison with other meta-models as a result of an evaluation can be found in the following document: File:EvaluationExistingMetamodels.pdf.

Metamodel and XPDL 1.0

The document File:AgilPro Metamodel.pdf describes an initial revision of the document comparing the JWT/AgilPro metamodel with the XPDL 1.0 schema. It covers all the XPDL elements as well as the Bonita engine vendor specific extensions.

Metamodel and BPMN

Please find under File:Comparison JWT BPMN v0 3.pdf a document describing the differences between the JWT Metamodel on the one hand and BPMN on the other.


Model extensions : how to use store custom information in (workflow) models using Conf, Profiles and Aspects

What it is for

JWT provides a mechanism allowing to store typed custom information in workflow models (actually, it works for any kind of EMF model). Profiles describe what kind of additional information can be stored on model elements. They can be provided by JWT integrators to let their users provide complex information needed by their custom features, or designed by end users to let them add information as simple as key-value properties.

Which plugins you need in your JWT installation (or workspace)

  • jwt-we obviously as well as jwt-we-conf.we, which contains aspect integration in jwt-we
  • conf (aspects) plugins : jwt-we-conf and .edit (or)
  • if you plan to use "dynamic" Properties, their plugins : jwt-we-conf-property and .edit
  • TEMPORARY 20081223 patch the jwt-we HEAD using the patch provided at https://bugs.eclipse.org/bugs/show_bug.cgi?id=241567

Enabling model extensions

To enable its custom Conf in your (workflow) model : if it is not already enabled for your xxx.workflow model, i.e. if it has no custom Conf already (xxx.workflow_conf file),

  • start from a vanilla (workflow) model xxx.workflow and open it.
  • open the ManageProfiles UI. One way is to select the corresponding editor sheet, or open it if it is not already by right click > Editor sheets > Manage Profiles. Another way could be : right click and select ExternalActions > ManageProfiles, which opens the ManageProfiles dialog.
  • Since there is no conf yet, the ManageProfiles UI is empty and only permits to activate profiles by clicking on a button
  • click on this button, which creates a related, empty conf file, named xxx.workflow_conf .

NB. this would also work for any kind of EMF model.

Using existing model extensions

To enrich your (workflow) model with custom information using Aspects from existing Profiles provided in your JWT installation,

  • ensure the conf file is not in embeddedConf mode,
  • then using the ManageProfiles dialog, select which profiles you want to activate for your (workflow) model
  • then design your (workflow) model and enrich them with custom information stored in allowed aspects
    • ex. creating aspects on nodes using right click on node > New Child > xxxaspect
    • or merely creating new nodes which have automatically created aspects registered on it
    • or using aspect-enriched views (like the "dynamic" Property PropertySheet tab, or the StaticAspect example PropertySheet tab)...
  • NB. extensions information and configuration are stored in the *_conf file, which must be provided along with your (workflow) model file

Installing third-party model extensions

To install third-party model extensions in your JWT installation,

  • if they are provided as plugin(s), install them from their update-site or put their jars in the "plugins" directory of your JWT installation and restart
  • if they are provided as autodiscovered _conf and .ecore (dynamic EMF case) files, put them in the "conf" autodiscovery directory and restart

Setting up simple additional model extensions

This can be done (without code nor EMF design) by designing and using "dynamic" Properties :

  • put the (workflow) model file in profile design mode (also called "embeddedConf" mode, by using the ManageProfile UI, or the PropertySheet on the ConfModel). This will allow the (workflow) model to directly use profiles available in its _conf file, and not only Profiles that are provided by the JWT installation.
  • create your own custom Profile in the _conf file, ex. by right-click > New Child> Profile on the ConfModel in the outline. Give it a distinct name and URL.
  • then start designing and testing new Property aspects in it :
    • ex. define one (or more) aspect(s) on your Profile using right click on it > New Child > New Aspect
    • then select jwt.we.conf.property.Property as its aspect instance type,
    • also give it a unique id and select which model element type(s) it will be available on
    • optionally, disable "autocreated" (so it will not be automatically created on any newly created node but will have to be created explicitly), enable "multiple" (so more than one can be created) or give it a default value (works only with primitive types for now)
  • and when they are ok, export it using the ManageProfile UI to astandalone .conf file,
  • which you'll register in a plugin or put in the "conf" autodiscovery directory of your JWT installation.
  • Now you can put the ConfModel's "embeddedConf" property to false again, since your new profile is available among the installed ones.
  • Therefore you can start using your custom designed model extensions in (workflow) models as shown previously.
  • NB. as said, property information and configuration are stored in the *_conf file, which must be provided along with your (workflow) model file

For advanced users : designing complex additional model extensions without code

This can be done by designing and using "dynamic EMF" aspects, i.e. with EMF design but without code :

  • design an EMF type extending jwt.we.conf.AspectInstance :
    • create a new EMF model file near your (workflow) model file by using the Eclipse New Ecore EMF model wizard
    • in it, name its package as you want and create there a new EMF type
    • in the sample EMF editor, right-click on it, choose "Load Resource..." and select among plugin resources jwt-we-conf-model's the ConfMetaModel.ecore
    • so you can let your new type extend jwt.we.conf.AspectInstance using the Extend Type dialog
    • design your custom model extension : add EMF attributes and references on your type, create other types or load them from other resources and refer to it...
  • then set it up in a custom Profile :
    • as above for setting up custom "dynamic" Properties, go in profile design mode, and in a custom Profile create a new Aspect
    • in the sample EMF editor, right-click on it, choose "Load Resource..." and select among file resources your custom metamodel
    • so you can let your aspect's instance type by the custom EMF type you've just designed
  • NB. you must provide your custom EMF metamodel file (and possible additional loaded file models), along with the _conf file in the same directory as your workflow models.

For developers : developing complex additional model extensions using EMF-generated code

This can be done by designing a custom EMF metamodel and generating its code to be used in Aspects :

  • use the Eclipse new EMF plugin project wizard to create a new project with an EMF model in it and its .genmodel companion file for configuring java code generation
  • like above, design in this new EMF model your own type extending jwt.we.conf.AspectInstance
  • open the companion .genmodel file and configure it accordingly, then use it to generate the model and .edit code, and optionally .editor code.
  • then again, set it up in a custom Profile, like above, and export it to its own .conf file.
  • Finally, register this .conf file in the project's plugin.xml using the jwt.we.conf extension point, along with the EMF model.
    • NB. this solution of registering the conf file can also be used in the "dynamic" EMF case above, though it is too complex for it


For EMF-based tool developers : enriching a model with extensions

For EMF-based tool developers : Extension alternatives

If you're developing an EMF-based tool, there are three ways to add custom information to an EMF model :

  • extend an existing type of the model with your own type. This is only interesting to create well identified subtypes, i.e. that could have been provided in the base model beforehand.
  • add instances of your own type to an openly typed reference (Any, EObject...). This is a good all-around solution but requires that such a reference exists in the model, and doesn't provide management of information coming from different third-party providers.
  • manage instances of your own types in another model that let them refer to the main model's elements. This non-intrusive solution works with any model without prerequisite and allows to share type extensions between model types. Aspects do this in a simple, typed way that allows for having custom-information coming from different third-party providers, while the genmodel file is a more complex example.

For EMF-based tool developers : allowing aspects (jwt-we-conf*) in your EMF model

  • put the aspects (jwt-we-conf*) plugins in your plugin Feature
  • let your model plugin depend from jwt-we-conf and the base classes of your EMF.edit's ItemProviders extend AspectsEnrichedBaseItemProvider rather than BaseItemProvider. This enables right-click > New Child > aspectxxx commands, as well as aspect behaviours (mainly autocreated aspects). Alternatively, you can write its code in your root generated class.
  • that's it ! If you want, you can now also develop a custm Property Sheet tab for your aspect, or a view, an editor sheet...