Nathalie Moreno and Antonio Vallecillo Dept. Lenguajes y Ciencias de la Computación Universidad de Málaga {vergara,av}@

1. BUSINESS COMPONENT STRUCTURAL BEHAVIORAL CHOREOGRAPHY What do we do in MDA with re-use? CIM PIM PSM Nathalie Moreno andAntonio Vallecillo Dept. Lenguajes y Ciencias de la Computación Universidad de Málaga {vergara,av}@lcc.uma.es COTS component/ Legacy System

2. Agenda • Introduction • The problems • Assumptions for addressing these problems • Dealing with the assumptions • Concluding remarks • Introduction • The problems • Assumptions for addressing these problems • Dealing with the assumptions • Concluding remarks

3. Our background and motivation • Component-based software development but... • ...moving to Web-based application design and development • Specific and well-defined application domain • Model compilers current exist for Web apps • They are successfully used in real environments • but... ad-hoc, unstructured, non-modular, hard to maintain and evolve, proprietary.... • Web Service technologies are proving to be valuable to organizations and starting to be widely used • Financial (VISA, AMEX), Travel agencies (TerminalA), E-shops (Amazon), Adobe, ... • Looks like the perfect arena for MDA!

4. MDA focus • MDA focuses on Models • CIM (?) • PIM • PSM • “Platform” Models • “Implementations” (=PSM) • Metamodels • MDA focuses on Transformations • PIM to PSM • PIM(s) to PSM • PSM to PIM • PIM(s) + “Additional Info” to PSM • Metamodel transformations

5. Transformation The “basic” MDA pattern • The basic MDA pattern includes (at least): • a PIM, • a Transformation, and • a PSM PIM PSM

6. Applying the MDA pattern “A model of a subsystem that contains no information specific to the platform, or the technology that is used to realize it.” TOP-DOWN PIM Transformation PSM

7. Transformation Applying the MDA pattern TOP-DOWN PIM “Converting one model to another model of the same system.” PSM

8. Applying the MDA pattern TOP-DOWN PIM Transformation “A model of a subsystem that includes information about the specific technology that is used in the realization of it on a specific platform, and hence possibly contains elements that are specific to the platform.” PSM

9. Agenda • Introduction • The problems • Assumptions for addressing these problems • Dealing with the assumptions • Concluding remarks

10. Initial problems • Related to the modelling of systems • What are the contents of the model of a system? • How is that information expressed? • Related to COTS/legacy systems • What are the contents of the model of a COTS? • How is that information expressed? • Is that information available? • Is that information reliable? • How can it be obtained? • Related to matchmaking/adaptation • How do I check whether the COTS software fulfils my system requirements? (Gap Analysis Problem) • How do I evaluate the effort required to adapt it? • How do I adapt it? ... Or revise my system specs?

11. COTS, legacy systems, and MDA • COTS components and Legacy Systems are black-boxes • Very few information is available about them • Just signature information, usually in textual form • Most of the available information may be outdated • Models, if available at all, correspond to the original design • Evolutions very few times reflect in the documentation • Reverse engineeringis not the solution • It provides a model at the lowest possible level of abstraction • Usually, just an execution model of the software in graphical form, • ..but without any architectural information • How do I match the requirements with the COTS information? • Traditional rule of thumb: if more than 20% needs to be adapted/modified, you better develop from scratch • Does this rule still apply in the context of MDA? • Can I generate adaptors that alleviate this problem?

12. Agenda • Introduction • The problems • Trying to address these issues • Dealing with the assumptions • Concluding remarks

13. STRUCTURAL MODEL BEHAVIORAL MODEL CHOREOGRAPHY MODEL  PIM LANGUAGE REVIEW  MDA TRANSFORMATION MDA TRANSFORMATION MDA TRANSFORMATION STRUCTURE BEHAVIOR CHOREOGRAPHY NO NO NO NO PSM LANGUAGE NO NO NO WORTH DEVELOPING? YES YES STRUCTURE BEHAVIOR CHOREOGRAPHY STRUCTURE BEHAVIOR CHOREOGRAPHY STRUCTURE BEHAVIOR CHOREOGRAPHY COMPONENT SPECIFICATION ADAPTER SPECIFICATION COTS SPECIFICATION DOCUMENTATION OR MDA TRANSFORMATION/ REV. ENGINEERING MDA TRANSFORMATION/ IMPLEMENTATION MDA TRANSFORMATION/ IMPLEMENTATION CODE GENERATED COMPONENT ADAPTER COTS (BLACK BOX) <? ADAPTABLE? ADAPTABLE? <? ADAPTABLE? <? BUSINESS COMPONENT

14. Based on the following assumptions • The PIM of the application we are developing describes the system as a set of interacting parts (e.g., services) • Each part is described by at least its structure, behaviour, and choreography • We count with a model of the COTS component or legacy system that we need to re-use (and hence a PSM metamodel), described similarly • There are MDA transformations defined between the PIM and the PSM metamodels • There is a set of matchmaking operators (<) that implement the sustitutability tests (“A<B” if “A can replace B”) • In case of mismatches, we know how to decide whether an adaptor exists or not • And if so, we know how to generate it Sci-Fi?

15. Agenda • Introduction • The problems • Assumptions for addressing these problems • Dealing with the assumptions • Concluding remarks

16. UML 2.0? How far we are • The PIM of the application we are developing describes the system as a set of interating parts (e.g., services) • We are not doing too bad here! • Each part is described by at least its structure, behaviour, and choreography • No problems with the structure, • But still far from reaching an agreement on how to model the behaviour and the choreography

17. How far we are 3. We count with a model of the COTS component or legacy system that we need to re-use (and hence a PSM metamodel), described similarly (i.e., with models for its structure, behaviourand choreography)

18. How far we are • There are MDA transformations defined between the PIM and the PSM metamodels • MOF/QVT may be of great help here! • Some proposals already available UML (Class Diagrams) <................> Java (Interfaces) EDOC <................> BPEL4WS

19. How far we are • 5. There is a set of matchmaking operators (<) that implement the sustitutability tests (A < B if A can replace B) • Situation under control at the structural (signature) level • Subtyping • Some works at the behavioural level (for pre-post specs, basically) • Larch-CORBA, Larch Java, ... • Some works at the choreography level • Petri-nets • The pi-calculus

20. How far we are • 6. In case of mismatches, we know how to decide wether an adator exists or not....And if so, how to generate it • Just preliminary results • Resolve mismatches found by the sustitutability tests • Unsolved yet: • defining distances between specifications • Deciding about the existence of wrappers that resolve the mismatches • Generating the wrappers

21. Agenda • Introduction • The problems • Assumptions for addressing these problems • Dealing with the assumptions • Concluding remarks

22. Summary • MDA and re-use • MDA seems to imply a top-down approach to software development (al least, when used for model compilation) • Re-use is critical in open, multivendor, distributed apps • Not only for designing them • But also for taking evolution into account • Re-use seems to imply somehow a bottom-upapproach • Can we reconcile both approaches? • We have presented a possible (partial) solution based on a set of (very strong) assumptions • Some work on these assumptions is currently undergoing • Frankly speaking, we see the assumptions feasible only in very few cases and application domains • Web-based applications development may be one of them • Could you think of others?

23. Antonio Vallecillo av@lcc.uma.es +34 952 13 27 94 End of Presentation Thanks!