1 Model-driven development of SOA with Web services – using QVT technology Master thesis by Berge Stillingen Department of Informatics, University of Oslo 2005

2 Problem domain and scope SOA – Service Oriented Architecture Focus is set on Web services MDA – Model Driven Architecture Framework for model-driven development QVT – Query/Views/Transformations Upcoming standard for model-to-model transformations from OMG MOF2Text – MOF Model to Text Transformations Upcoming standard for model-to-text transformations from OMG Thesis approach: – Where is QVT today? – Is QVT the right answer when developing SOA using MDD?

3 Contents I: Feature analysis: QVT/MOF2Text candidates II: MOSUQ: SOA/QVT/MOF2Text framework – Concepts – Transformation assets for Java Web services III: Case study: Min/Max replenishment system specified using the framework

4 (I) Feature analysis Evaluating proposals to the QVT and MOF2Text standards and belonging software (proof of concept) – Analyze their features deriving criteria/requirements from the QVT and MOF2Text RFPs (Request For Proposals to standards) – Add additional tool-specific requirements for the proofs of concept – Give points for each criteria (e.g. 2/5) – The 2 alternatives: QVTMOF2Text Alt. 1:QVT-Merge Group ATL SINTEF/Softeam MOFScript Alt. 2:EXMOF OptimalJ MOF2Text-partners OptimalJ (TPL) – Sum up and use the “winning” alternative to specify transformations for a SOA-MDD framework and case study

5 Requirements/Evaluation criteria Model-to-model trans. (QVT) Declarative transformation definitions/Model querying – Based on OCL Incremental transformations Reuse of existing OMG specifications – OCL, UML, MOF (Meta Object Facility) MOF 2.0 based transformations/models Additional transformation data Traceability – Importing for debugging Graphical and textual notation …

6 Requirements/Evaluation criteria Model-to-text trans. (MOF2Text) Reuse of existing OMG language specifications MOF 2.0 based mappings/source models Functions for string manipulation Combining model data with clear text Complex text transformation mappings – Most mappings are one-to-one (isomorphic) – More non-trivial mappings may occurs Multiple models and support for UML extensibility mechanism …

7 Requirements/Evaluation criteria Other requirements. (tool-specific) Note: Applies to the proofs-of-concept in both alternatives and both QVT and MOF2Text. OMG standards – UML 2.0 and XMI 2.0 support Explicit UML profile support using multiple files Code assistance Debugging facilities Testing well-formedness

8 Feature analysis results Alternative 1 wins with a 63% score (alt.2 gets a 55% score) – Low scores, especially on model-to-model transformations Results worst for the tool-specific req. (other req.) – OptimalJ: Gives Alt 2. a better score. A more “easy to use” tool than ATL/MOFScript QVTMOF2Text Alt. 1:QVT-Merge Group ATL SINTEF/Softeam MOFScript Alt. 2:EXMOF OptimalJ MOF2Text-partners OptimalJ (TPL)

9 (II) MOSUQ – SOA QVT Framework Model-driven development Of Service Oriented Architectures Using QVT – Implies use of the MOF2Text standard as well Combined QVT and MOF2Text usage – Serve conceptual guidelines for MDD of SOA using the two standards Specified concretely for Java Web services Transformations assets: – QVT Merge relations (graphical) – QVT Merge mappings (textual) – ATL transformations – COMET’s Service Architecture modeling

10 MOSUQ concepts Draw a COMET based Service Architecture Model – Use COMET stereotypes Define a PSM domain for a SOA based platform (main platform) Define wanted artifacts at the code level Identify “sub-platforms” for the PSM domain – Defined by UML profiles or MOF metamodels Refine the PSM domain – Add transformations between the abstraction layers – Use 3 or more abstraction layers

11 MDD Java Web services 4 sub-platforms identified – WSDL (using MOF metamodel) – JAX-RPC – Java – Sun/J2EE – Details of the three latter reflected in a UML profile PSM domain refined 4 transformations added refined

12 Metamodels for the PSMs (1) UML 2.0 MM With Java Web services UML profile

13 Metamodels for the PSMs (2) WSDL metamodel

14 implementing realizing MDD Java Web services Transformation assets: – QVT Merge relations – QVT Merge mappings – ATL code – MOFScript code

15 Implementing transformations - Working environment Eclipse based IDE: Rational Software Modeler + ATL transformation engine + MOFScript XMI Source metamodel (EMF) Target metamodel (EMF) ATL engine Service Model Platform model (UML profile or MOF metamodel based) XMI Source metamodel (EMF) ATL code MOFScript code Code/ text artefacts Code/ text artefacts MOFScript engine XMI

16 Case study: Min/Max Replenishment - applying the MOSUQ framework

17 Case study: Min/Max Replenishment - Service Architecture Model (COMET) Component model Interface Model Information Model PIM Data types

18 Case study: Min/Max Replenishment - Platform models (1) WS UML model – Trans 1. applied

19 Case study: Min/Max Replenishment - Platform models (2) WSDL model – Shown as object diagram – Trans. 2 applied

20 Case study: Min/Max Replenishment - Code artefacts Java Code – Transformation 3 applied Value object classes Web service interface classes Web service implementation classes Validated with Eclipse’s Java compiler WSDL (XML) – Transformation 4 applied Example with Rpc/literal messaging style Validated with a WDSL XML Schema instance

21 Why use MOSUQ? - especially concerning the generation of Java code and WSDL documents No PSM (traditional) approach: – PIM to text transformation (code generation) Annotation of PIMs (stereotypes, tagged values) – w/Additional transformation data No intermediate PSMs One transformation per target artefact at the implementation level (code etc.) Only one language to use MOSUQ (more MDA adherent): – PIM to PSM transformations – PSM to text and/or PSM to PSM transformations Commit to multiple ways (languages) of specifying transformation assets Ensures correcting structuring of target specifications reflecting code/text at the implementation level – Given a well-defined metamodel. – Less chance of generating text artefacts violating syntax Separation of concerns – Formalizing the details of identified platforms by using MM

22 Conclusions - summary of contributions Evaluation of proposals to QVT and MOF2Text with their belonging proofs-of-concept – Feature analysis: 63% score on alt. 1 (QVT Merge/ATL/MOFScript) Still work to be done, especially on the tool side MOSUQ – SOA/QVT framework – Transformations assets Subject to reuse/alterations – ATL code (difficult and time-consuming) – MOFScript code – QVT Merge specifications – Has proven that the QVT and MOF2Text standards can be combined to realize MDD of SOA An alternative to MDD of SOA

23 Future work Alternative QVT-tools: – AMW/AMMA (INRIA) Lets you define correspondence specifications in the form of weaving models between model artefacts Capable of expressing symmetric rules Transformations in different languages can be generated (XSLT, ATL) – Model Transformation Framework (MTF) Consistency-checking capabilities MOSUQ enhancements – Apply other PSM profiles for SOA impl.: BPEL/BPMN Configuration files (DD etc) CORBA/IDL XML registries and UDDI dot NET platform