EclipseCon2010 - Painless Metamodel Evolution

Painless (?) Metamodel Evolution A pragmatic approach Eclipse Con 2010 Christian Saad (University of Augsburg, DE) Etienne Juliot (Obeo, FR) Marc Dutoo (Open Wide, FR) Confidential | Date | Other Information, if necessary © 2002 IBM Corporation

About the speakers Christian Saad - University of Augsburg • Research assistant at the University of Augsburg • Topics of interest: Model analysis, business process management Etienne Juliot - founder of Obeo, FR • Contributes to several Eclipse projects (SCA Tools, Acceleo, ATL, EEF, ...) and OpenSource communities Marc Dutoo - SOA, BPM, ECM architect • Head of R&D Dept. at Open Wide, a French Open Source software integrator With the support of • Stéphane Drapeau, Obeo, FR • The Java Workflow Tooling (JWT) and SCA projects Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 2

Overview Metamodel evolution is painful ! JWT (migration) use case - practices - technologies - automating it SCA (extensions) use case - analysis - solution Further Conclusion Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 3

Metamodels do evolve ! along with The business domain • Driven by new requirements or standards • Concepts or attributes may be added or become obsolete Internal features Driven by features of the modeling tool itself Ex: layout information External features • Driven by model usage • Ex: runtime information (logging, transactions) in workflows Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 4

Metamodel changes are... (too?!) easy to design (EMF & co) painful to cope with – for devs and users alike • old models must be migrated (tedious and boring) • or their legacy metamodels maintained (defeats the purpose)... • …if there's actually someone caring enough and metamodel evolutions never stop they just pile up ! ... everyone who has really used modeling / MDA has experienced it ! Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 5

Introducing the JWT use case we experienced it at our project • Java Workflow Tooling (JWT) • An extensible Workflow tool suite in the SOA TLP all the more because it aims at • an extensible model (through aspect-like extensions) that allows to support different runtimes • different GEF-based views on top of it • compatibility with other workflow standards (through transformations) Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 6

1. Alleviating the pain - diagnostic Know where you are • store a version number in the model • version-specific namespace: pros and cons • Use it if your technology allows it – see next Manage evolutions • talk about them! (Wiki, release notes, warning dialogs) • write howtos on evolving legacy models in bugzillas • ex. "all nodes with a X=Y property now are of type Z" But • The user still has to do everything, so it hurts ! Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 7

1. Alleviating the pain – practices Modeling practices: “eager” changes • Adding new nodes breaks nothing • However Deleting/Refactoring does Provide abstract nodes with generic semantics − Default behaviours are inherited − Ex: Subclassing JWT ExecutableNode Write unit tests which load sample models! But Beware of being restricted in metamodel evolutions that won't break "too much" legacy models Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 8

2. Scalpels - using technologies Been there, done that : • you've migrated two models by hand, and don't want to do it again. So code the evolution rules that you documented! • Ex.: Java EMF - lighter : scripting (groovy) BUT source and target metamodels are different: • load both: But still has to code the copy of the part of the original model that didn't change (most of it actually) A simple, content-oriented solution : XSL • breaking free from java, code, EMF (for best… and worse) An EMF solution : ATL • EMF based model to model transformations … and provide these to model users! • extend the EMF editor actions (yours or the original one), up to... Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 9

3. Healing - automating evolution Make the evolution transparent • When evolving (meta)models , most of the work is the same • Check version, if not the same as your tool's, find and apply required transformation JWT’s ATL model converter • Lightweight ATL-based framework • Developers only need to slightly adapt the ATL transformation • Ask users whether they are OK with automatic transformation before manipulating files! Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 10

Introducing the SCA Tools project Service Component Architecture (SCA) aims to provide A model for the creation of service components in a wide range of languages and A model for assembling service components into a business solution SCA Tools project is a set of tools for developers of SCA applications The project was created under the SOA Tools Platform (STP) TLP SOA The project is moving to the new SOA TLP (move Top Level review planned April 7) Project Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 11

SCA "two-headed" metamodel and its extensions SCA was initiated by the Open SOA consortium → SCA specifications 1.0 Currently, the OASIS Open Composite Services Architecture (CSA) Member Section is standardizing SCA → SCA specifications 1.1 Each runtime extends the SCA specifications with additional Implementation, Interface and Binding types SCA SCA OSOA OASIS Tuscany FraSCAti Tuscany Runtime x Runtime y 1.x 1.x 2.x Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 12

SCA "two-headed" metamodel and its extensions SCA was initiated by the Open SOA consortium a set of tools Objective: to propose (XML editors, GMF editors, launchers, → SCA specifications 1.0 ...) based on all these metamodels Currently, the OASIS Open Composite Services Architecture (CSA) Member Sectionuser must have the impression The is standardizing SCA he is using the same tool when he → SCA specifications 1.1 defines an SCA-OSOA or an Each runtime extends the SCA specifications with SCA-OASIS artefact! additional Implementation, Interface and Binding types SCA SCA OSOA OASIS Tuscany FraSCAti Tuscany Runtime x Runtime y 1.x 1.x 2.x Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 13

How we support the "two-headed" metamodel For each SCA specifications (OSOA and OASIS), we generated the metamodel and the GMF designer The same SCA runtimes extension mechanism is used The "two-headed" metamodel and the extensions specific to the different SCA runtimes are SCA-OASIS SCA-OSOA transparent for the user Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 14

How do we support the SCA runtimes extensions? A core metamodel: SCA-OSOA or SCA-OASIS Extensions proposed by the SCA runtimes concern only the Implementation, Interface and Binding types Extension of the core metamodels is easy Use the "Child Creation Extenders" and "Extensible Provider Factory" options proposed in the .genmodel Extension of the GMF modeler is more difficult GMF does not take into account the extension options proposed by EMF → Specific code in the sca.diagram plugin → New plugin (sca.diagram.extension) to dynamically take into account the extensions Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 15

Create your own extension First step: extend the SCA metamodel Create a new metamodel Create a DocumentRoot that extends the DocumentRoot of the SCA metamodel Create your own elements that extend Implementation, Interface or Binding Generate the code Second step: extend the Composite Designer org.eclipse.gmf.runtime.emf.type.core.elementTypes org.eclipse.gmf.runtime.emf.type.core.elementTypeBindings … Third step: Extend existing ATL transformations and Acceleo generators Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 16

Further COPE by TUM Munich University (http://cope.in.tum.de) • Transformations • by recording metamodel changes • Mixes automatic and manually defined ones High level transformation definition • But • Developers must be “convinced” to follow this procedure • Overhead when “trying out” new things in your models • Changes in semantics only recorded in developer’s mind! // 1. metamodel adaptation Signature.inPort.eType = newClass("InPort", [Port]) Signature.outPort.eType = newClass("OutPort", [Port]) Port.’abstract’ = true // 2. model migration for(signature in Signature.instances) { for(port in signature.inPort) port.migrate(InPort) for(port in signature.outPort) port.migrate(OutPort) } Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 17

Further Eclipse Edapt • New project under EMFT • Goals • Migration of model instances, editors, transformations • Attaching migration instructions to change history • Approaches • Recording changes (COPE) • Extracting changes (EMF Compare) Semantic “tagging” of meta model elements • Research topic • Fit for every day use? Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 18

Conclusion From alleviating the pain, up to automated “healing” JWT use case • ATL converter : robust and versatile • Next: graphical UI help, help migrating models referred by other models, help migrating model transformations... SCA "two-headed" metamodel use case • Simple at EMF model level, harder at GMF UI level, but at the end transparent for the user • SCA metamodel can be used by others tools: ATL (module superimposition), Acceleo (dynamic templates), EEF What about your own experiences ? Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 19

Thanks for your attention ! A ny questions? ? ? Contact us at christian.saad@informatik.uni-augsburg.de or etienne.juliot@obeo.fr or marc.dutoo@openwide.fr JWT website & wiki: http://www.eclipse.org/jwt SCA website : http://wiki.eclipse.org/STP/SCA_Component We thank for his assistance: Stephane Drapeau, Obeo, FR – SCA project leader Eclipse Foundation, Inc. | © 2010 by the Open Wide, Obeo and University of Augsburg. Made available under the EPL v1.0 20

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EclipseCon2010 - Painless Metamodel Evolution

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