JWT Metamodel Extension
What are aspect model extensions for
JWT provides a mechanism allowing to store typed custom information in workflow models, thanks to an additional *_conf file (actually, it works for any kind of EMF model). Profiles describe what kind of additional information (or Aspects) can be stored on model elements. Such profiles and aspects 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.
- How they fit int the whole JWT_Metamodel
- Their initial specifications: JWT Metamodel Extension Specifications
Using aspect model extensions
Aspect model extensions should be available by default in your JWT installation starting from 0.6 (upcoming).
If they are not, here are the additional JWT eclipse 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,
- provided 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
Creating custom aspect model extensions
Setting up simple (key-value) additional model extensions
This can be done (without code nor EMF design) thanks to the jwt-we-conf-property official JWT metamodel extension :
- 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 other EMF-based tool developers : enriching a model with extensions
WARNING: this is only of interest if you're developing your own EMF-based tool and are interested in JWT Aspect metamodel extensions to let your own model accept custom information.
EMF model extension alternatives
Here we provide a short foray into EMF model extension alternatives. For more information, look up JWT Metamodel Extension Specifications.
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. If it is the case, please consider contributing it to JWT's core metamodel.
- 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. Therefore we didn't do so in JWT.
- 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. In JWT, 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.
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 custom Property Sheet tab for your aspect, or a view, an editor sheet...