1. Business Integration Technologies http://bpia.zurich.ibm.com © 2006 IBM Corporation Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Validation of Model Transformations - First Experiences using a White Box Approach Jochen Küster 1, Mohamed Abd-El-Razik 2 1 IBM Research, 2 IBM Cairo Technology Development Center

2. Validation of Model Transformations © 2006 IBM Corporation 2 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Outline of the talk  Model Transformations for Business Process Models  Testing Techniques for Model Transformations  Conclusions

3. Validation of Model Transformations © 2006 IBM Corporation 3 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com IT Solution Business Process Model Business Requirements Business Model Technology BPEL, WSDL, J2EE, WebSphere Model refinement Model transformation business process monitoring, change of strategy Business-driven development comprises:  Modeling of business processes  Transformation and refinement of business process models  Mapping of processes to Service-oriented Architecture Background: Business-Driven Development

4. Validation of Model Transformations © 2006 IBM Corporation 4 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Model Transformations on Business Process Models  Cycle Removal Transformation  Transformations for Abstraction and Refinement  Transformations into a Normal Form (Control Action To Pinset) Control Action To Pinset transformation

5. Validation of Model Transformations © 2006 IBM Corporation 5 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Conceptual Rules for Transformation Design A B1B1 BnBn A B1B1 BnBn..  Conceptual rules capture the main concepts of the transformation  Conceptual rules are refined into concrete rules by: –Replacing abstract node types with concrete ones –Replacing abstract edges with possible instantiations –Replacing abstract pin sets with possible instantiations  large meta model and elaborate OCL constraints  model transformation is implemented in Java using a transformation framework A Abstract node type: Abstract pinset: Abstract edge:

6. Validation of Model Transformations © 2006 IBM Corporation 6 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Outline of the talk  Model Transformations for Business Process Models  Testing Techniques for Model Transformations  Conclusions

7. Validation of Model Transformations © 2006 IBM Corporation 7 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Motivation for Testing Model Transformations Statement: “Model Transformations are software too.”  need to be properly tested in order to ensure their quality  have specific characteristics that require special test case generation approaches Testing challenges:  Generation of test cases from model transformation specifications  Generation of test oracles for determining expected result of test

8. Validation of Model Transformations © 2006 IBM Corporation 8 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Fault Model for Model Transformations Fault Model: what errors are we looking for?  Meta model coverage: Some input models are not transformed because conceptual rule has not been refined completely  Syntactically incorrect models: Output model is not syntactically correct (e.g. OCL constraint violated)  Semantically incorrect models: Output model is not semantically correct (e.g. Fork has been replaced by an implicit decision)  Confluence errors: Transformation produces different outputs on the same (or equivalent) input model  Correctness of transformation semantics: Transformation does not preserve a desired property

9. Validation of Model Transformations © 2006 IBM Corporation 9 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Meta model coverage testing (1) Goal: Ensure meta model coverage of a conceptual rule Approach: Convert conceptual rule into a template  Make selected abstract elements concrete  Parameterize remaining abstract elements by meta classes Conceptual rule: A B1B1 BnBn A B1B1 BnBn.. Y Z X Template(X,Y,Z): X={StartNode, Fork, Join, Decision, Merge, Task, Subprocess, LoopNode, Broadcast, AcceptSignal} Y={FinalNode, Fork, Join, Decision, Merge, Task, Subprocess, LoopNode, Broadcast, AcceptSignal, Map} Z={FinalNode, Fork, Join, Decision, Merge, Task, Subprocess, LoopNode, Broadcast, AcceptSignal, Map} Abstract pins and pin sets Concrete elements

10. Validation of Model Transformations © 2006 IBM Corporation 10 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Meta model coverage testing (2) Benefits:  can be used for ensuring meta model coverage of implemented rules  can be used for finding selected syntactic and semantic errors Drawbacks:  properties that are not restricted to one rule cannot be validated Test Cases:  Template can be used to generate test cases automatically  Test cases can be used for automated testing

11. Validation of Model Transformations © 2006 IBM Corporation 11 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Constraint-based testing Goal: Ensure that the model transformation does not violate constraints (e.g. OCL constraints) Approach:  Identify model elements changed by the transformation (automatable)  Identify constraints that may be violated (automatable)  Construct a test case for each constraint (manually) Constraint: A Loopnode has one regular output pin set Test case:

12. Validation of Model Transformations © 2006 IBM Corporation 12 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Rule Pair Testing (1) Goal: Find confluence errors by testing Background:  confluence requires that application of rules on the same model always yields the same result  rules can be analysed and verified whether they are confluent or not (see J. Küster, Definition and Validation of Model Transformations, SOSYM 5(3), September 2006 )  absence of complete specification of rules: Testing for confluence using suitable test cases

13. Validation of Model Transformations © 2006 IBM Corporation 13 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Rule Pair Testing (2) Approach:  test cases obtained by constructing models by overlapping the left sides of two rules  throw away incorrect models A B1B1 BnBn.. A2A2 C1C1 CnCn Rule r 3 Rule r 1 Possible test case obtained by overlapping: A 2 = Fork, B 1 = Decision

14. Validation of Model Transformations © 2006 IBM Corporation 14 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Conclusions and Future Work  Model transformations need appropriate testing techniques in order to ensure their quality  Testing techniques need to take into account fault model and implementation environment  Meta model coverage, constraint-based and rule pairs for test cases proposed Future work:  Automatic generation of test cases for constraints  Tool support

15. Validation of Model Transformations © 2006 IBM Corporation 15 Zurich Research Laboratory - BIT http://bpia.zurich.ibm.com Business Integration Technologies @ Zurich Research  The Business Integration Technologies group is part of a world-wide research initiative on Model-Driven Business Transformation.  BIT focuses on technologies for business-driven development. Integrate Transform Manage Monitor Model Process modeling methodologies Reference model customization Process model quality assurance Flow-driven and state-driven modeling Process Model Refinement Top-down and Bottom-up transformations - Analysis to Design model transformations - Capturing of IT requirements & architectural mismatches