Eclipse Summit 2009 - Aspect Oriented Modeling

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Aspect Oriented ModelingEclipse Summit Europe 2009

Florian Lautenbacher (University of Augsburg, DE)

Marc Dutoo (Open Wide, FR)

Eclipse Foundation, Inc. | © 2009 by the Open Wide and University of Augsburg. Made available under the EPL v1.0 2

Overview

Introducing Aspects

Requirements for the modeling domain

EMF – annotations and any*

Exploring EMF techniques

Inversion of Control – genmodel as an example

Managing extensions & an AOM framework

AOM Beyond EMF

Conclusion

Eclipse Foundation, Inc. | © 2009 by the Open Wide and University of Augsburg. Made available under the EPL v1.0 3

Introducing Aspects

An aspect is a unit of modularization of a crosscutting concern with respect to another concerns

Aspect Oriented Programming (AOP)• Has now pervaded software architecture and development.

• Dedicated language features (ex. Traits in Scala)

• Intrusive (ex. AspectJ in Java) or not (ex. Spring proxies).

The benefits:• Separation of features (logging, security, transactions..)

• Improve the readability and maintenance of code

The concept of Aspect transcends programming and has echoes in a lot of other areas, as e.g. in modeling.

Eclipse Foundation, Inc. | © 2009 by the Open Wide and University of Augsburg. Made available under the EPL v1.0 4

Aspect-Oriented Programming and Modeling

Composition points are defined in a join pointmodel

A set of composition points is selected throughPointcut expressions

Composing is done by an aspect weaver (duringdesign / load / runtime).

Distinction of aspects:• Homogeneous aspects: Same aspect used at several places

• Heterogeneous aspects: Different aspects at these places.

About Workflows, distinction of join points:• Activity join points (or process-level join points)

• Internal join points (interpretation-level join points)

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Introduction – Extending Models

Idea and Requirement: Extending models

With additional metamodel elements With additional properties

Why?

Store information that shall not be visible at runtime Enrich the meta model with data required by applications

Example: in Bonita 4 Workflow Engine, code execution “Hooks”

Allow support for custom actions

Examples: Logging, send emails on specific actions

but also development time information, like UI

A generic solution for such problems is needed!

Eclipse Foundation, Inc. | © 2009 by the Open Wide and University of Augsburg. Made available under the EPL v1.0 6

Example: Different views on a workflow 1/2

UML View

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Example: Different views on a workflow 2/2

Event-DrivenProcess Chain (EPC) View

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Simple EMF technique : EMF Annotations

Classified by Source, contains a key-value map

Example: STP BPMN

Simple and all-purpose However, not typed, not appropriate to business &

domain modeling

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Simple EMF technique : any* slot

i.e. “untyped” multiple containment reference

Can be used for domain specific modeling

Example: Implementations in STP SCA

Disadvantages : •The model is encumbered by extensions•Extension definitions must always be present•Version management is difficult

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Further exploring EMF Modeling techniques

A common way to do it : EMF modeling !i.e. creating a « single shot » specific EMF extension

Usually extensibility is defined according to needs• Adding custom information to an element requires subclassing it

• In EMF: support through Child Creation Extenders feature

Problem: what happens with many optional extensions that the user can enable “on demand”?

• Having several such custom extensions (e.g. from different vendors) would mean to create a new node type that inherits from all of them

• Neither flexible nor open to the end user

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Adding Inversion of Control

The extension model references the enriched model

Example: JWT‟s genmodel vs ecore model

Enables domain specific modeling, but…

Still no way to manage extensions coming from several different providers enriching the same model

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Managing model extensions : JWT Conf Model

Our solution: the JWT Conf model and framework

Example: Logging

Eclipse Foundation, Inc. | © 2009 by the Open Wide and University of Augsburg. Made available under the EPL v1.0 13

How does the JWT Conf Model work ?

Aspect-oriented extensions of the Workflow Editor EMF models are enriched through a Configuration (ConfModel)

consisting of Profiles (features)

Typed Aspects are defined in Profiles

Aspects are instantiated on elements of the decorated model

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Towards an AOM framework

Governance

For now, processes (in our case, documented on the wiki)

Going further, envisioning a repository of compatible types and extensions

Additions to the UI emf.edit extensions (display Aspects in Outline and Property Sheet) emf.editor-based default editor And also custom property tabs

Sample Aspects Custom Properties : all purpose

key-value Semantic annotations (in SemPro) SCA, RMI Actions (in OW2 Scarbo)

Eclipse Foundation, Inc. | © 2009 by the Open Wide and University of Augsburg. Made available under the EPL v1.0 15

AOM Beyond EMF: OMG proposal

One of the first submissions for the OMG RFP « MOF Support for Semantic Structures » (SMOF)

included the concept of Facets to representinformation about different views on one object in possibly different contexts.

«A facet is a MOF element that describessomething identified in the world. Multiple facets may contribute to the understanding of that thing in the world. »

NB. The latest version of the joint submission does not include this idea anymore.

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AOM Beyond EMF: BPMN 2.0

In its current draft version, BPMN 2.0 will alsoprovide the possibility to extend the metamodel with definitions from the outside

Only attributesthough

Could be modeledby a dedicatedAspect

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Conclusion

AO principles were applied on modeling through AOM specific techniques in EMF

Supported by a generic AOM framework

Benefits of Aspects in our use case Provide additional nodes that don„t exist in the original

metamodel

Call vendor specific custom actions for specific model elements

Have additional properties on already existing metamodelelements

Next steps Improve Conf model editor, wizards…

Making it fully independent of JWT

Eclipse Foundation, Inc. | © 2009 by the Open Wide and University of Augsburg. Made available under the EPL v1.0 18

Thanks for your attention !

We thank for his assistance:

Christian Saad – University of Augsburg, Committer on JWT

Any questions???Contact us at [email protected]

or [email protected]

JWT Conf Framework Documentation : http://wiki.eclipse.org/JWT_Metamodel_Extension

& Have a look at the latest Eclipse Magazin !