Interoperability, Automation, Built-in Evolution: the DEVS Framework for Coping with Emerging Complexity

1. Interoperability, Automation, Built-in Evolution: the DEVS Framework for Coping with Emerging Complexity Bernard P. Zeigler Arizona Center for Integrative Modeling and Simulation University of Arizona, Tucson and RTSync Corporation 1

2. IT Systems Developmental Complexity? IT Systems Developmental Complexity = degrees of developmental freedom � interdependence of design decisions � special requirements of environments IT Complexity explosion is driven by faster, cheaper computers, networking, web middleware, �, Emergence: each stage enables the next stage with accelerating options for further growth Wherever choices in platform, language,�, line of code, are possible, different developers will make different choices Underlying structure/behavior dependencies force local decisions to have global impact breaking neat design patterns Environments impose a plethora of special situations and an exponentially growing number of parameter combinations. 2

3. Consequences of complexity explosion: Proliferation of incompatible variations on same themes Ubiquitous heterogeneity Vertical integration - �Stove piping� 3

4. UML (Unified Modeling Language) Is the most widely used framework to support model driven development Promoted by Object Management Group as a standard within its Model Driven Architecture (MDA) Supported by increasingly powerful commercial tools Enhanced by SysML supporting requirements front end Incorporated in architectural frameworks: DoDAF, MoDAF, � 4

5. Issues In Developmental Complexity of IT Systems Often development does not start from scratch Conditioned by idiosyncratic requirements Powered, but unconstrained, by applicable standards Requires legacy subsystem integration Rigorous testing is needed to cope with complexity Methodology must scale with growth and evolution of system UML/MDA offers only limited support to address these concerns 5

6. Formulate the Issues within a Formal System of System Models (SoSM) Concept SoSM = collection of disparate system models to be federated to satisfy new simulation requirements Each participating system model may itself be large and complex Participant models usually have become efficient at achieving their own specialized requirements Participant models often adhere to idiosyncratic formalisms and development approaches Distinguish between interoperation and integration to set appropriate objectives 6

7. Interoperation vs Integration* Interoperation of system components participants remain autonomous and independent loosely coupled interaction rules are soft coded local data vocabularies persist share information via mediation 7

8. DEVS Framework Discrete Event Systems Specification (DEVS) is the basis for a formal framework for modeling and simulation DEVS contributes to scalability by: Offering a standard for distributed simulation to support interoperability, composability, and reuse Exploiting the separation between model, experimental frame and simulator Fostering model continuity and progressive development Automating and integrating complex systems implementation and testing Emulating the biological brain for its "built-in" correlation of activity and behavior to drive efficient evolution via component re-us 8

9. Web Service Oriented Architecture Basis for M&S 9

10. Approach to Current Issues in SoSM Adopt Web-enabled M&S Concepts for composing SoSM Exploit SOA infrastructure for Model Repository and Component Reuse Develop Formal Dynamic SoSM Distributed Simulation Standard Build on this foundation to support Higher Levels of Interoperability Develop automated and integrated development and testing methodology 10

11. SOA-enabled Model Repository Composability and Reuse * 11

12. Success Story: DEVS-based Joint MEASURE � Model Repository Reuse* 12

13. Linguistic Levels of Information Exchange and Interoperability 13

14. DEVS Standardization Supports Higher Level Web-Centric Interoperability 14

17. DEVS-Based Net-Centric Systems Test Agent Capability

18. Summary� Model-driven methodology employs technology-independent software abstractions, e.g., in UML, to support diverse implementation platforms and enable reuse and automation Existing interoperability standards do not provide needed separation between models and simulations and do not effectively constrain object models System of System Modeling (SoSM) concepts go beyond UML/MDA to address issues in interoperability, composability, and reuse DEVS system theory �based framework operationalizes SoSM concepts and supports automated, rigorous testing in realistic GIG/SOA environments 18

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20. More Demos and Links http://www.acims.arizona.edu/demos/demos.shtml Integrated Development and Testing Methodology: AutoDEVS (ppt) & DEMO Natural language-based Automated DEVS model generation BPMN/BPEL-based� Automated DEVS model generation Net-centric SOA Execution of DEVS models DEVS Unified Process for Integrated Development and Testing of SOA Intrusion Detection System on DEVS/SOA 20

21. DEVS/SOA Infrastructure: Supports Deployment and Execution of DEVS Models on the Web

22. Test agents are DEVS models and Experimental Frames They are deployed to observe selected participant via their service invocations 22