1. Systems Modeling and Analysis Using Colored Petri Nets Vijay Gehlot Center of Excellence in Enterprise Technology Department of Computing Sciences

2. Net-Centric Validation Conference 2007 2 CEET Conference 20072 Outline Introduction CPN Overview CPN Model of WMDNs SOA in Defense Presence/Discovery Model

3. Net-Centric Validation Conference 2007 3 CEET Conference 20073 Ariane 5 Failure Ariane 5, ESA Maiden Flight, 6/4/1996 37 sec later self-destructs Root cause: uncaught overflow exception

4. Net-Centric Validation Conference 2007 4 CEET Conference 20074 Mars Climate Orbiter Failure Mars Climate Orbiter, NASA Launched, 12/11/1998 Lost, 9/23/1999 Root cause: failed translation of English units into metric units in a segment of ground-based, navigation-related mission software

5. Net-Centric Validation Conference 2007 5 CEET Conference 20075 London Ambulance Service Failure Computer Aided Dispatch Introduced 10/26/1992 Within days major system failure  Vehicle positions incorrectly recorded  Multiple vehicles dispatched to same location  Severe delays  Lives lost

6. Net-Centric Validation Conference 2007 6 CEET Conference 20076 Airbus A320 Failure

7. Net-Centric Validation Conference 2007 7 CEET Conference 20077 Why Does This Matter? Computer systems perform many critical tasks Safety-critical systems will dominate Already complex nature of software SOAs and Net-centricity add dimensions of concurrent and distributed computations Systems for defense applications have very high dependability requirements Complex interactions that are hard to predict Consequences of failure  Injury, loss of life, environmental damage, financial loss, …  E.g, system downtime cost to brokerage operations: $7 Million/Hour  Cost of software defects: $200 Billion/Year

8. Net-Centric Validation Conference 2007 8 CEET Conference 20078 Current State From a recent report The Challenges of Complex IT Projects (Royal Academy of Engineering and British Computer Society): “The pace of technological change and the ferociously competitive nature of the industry...... lead to the triumph of speed over thoughtfulness, of the maverick shortcut over discipline, and the focus on the short term.”

9. Net-Centric Validation Conference 2007 9 CEET Conference 20079 Hope Robin Milner, a prominent computer scientist, in a lecture of January 2007: “The software industry [and the report] focuses on managing software production [process], not on understanding software itself [science of software]. … Grand Challenge: Establish modeling as the basis of informatics.”

10. Net-Centric Validation Conference 2007 10 CEET Conference 200710 Desire Keynote Address by Mark Schaeffer, Director, Systems & Software Engineering, Office of Under Secretary of Defense, Acquisition & Technology, IEEE Systems Conference, Honolulu, Hawaii, April 2007: “...System assurance is still a challenge … Use modeling and simulation to help refine warfighter concept of operations, system requirements, evaluate design alternative and identify constraints...”

11. Net-Centric Validation Conference 2007 11 CEET Conference 200711 An Example-Wireless Medical Device Networks Similar situations in defense and other settings too Modeled patient scenario with  Heart alarms  Pulse oxymeters alarms  Low battery alarms Used Colored Petri Nets

12. Net-Centric Validation Conference 2007 12 CEET Conference 200712 Colored Petri Nets Graphical modelling language Combination of Petri Nets and Programming Language Module support for hierarchical construction Support for both timed and untimed models Petri Nets: concurrency control structures synchronisation communication resource sharing CPN ML: data and manipulation compact modelling

13. Net-Centric Validation Conference 2007 13 CEET Conference 200713 Analysis CPN Tools software for model construction and analysis Interactive- and automatic simulation Application domain visualization Simulation-based performance analysis State space construction, analysis, and verification External process communication

14. Net-Centric Validation Conference 2007 14 CEET Conference 200714 CPN Model of WMDN

15. Net-Centric Validation Conference 2007 15 CEET Conference 200715 Results and Implications Need for QoS requirement for medical applications Similar situation in other application domains

16. Net-Centric Validation Conference 2007 16 CEET Conference 200716 Net-Centricity in DoD Context

17. Net-Centric Validation Conference 2007 17 CEET Conference 200717 SOA for DoD Applications Application characteristics include:  Presence/Availability awareness  Dynamic service discovery  Interoperable multiple connection types  Load balancing  … One implementation: SIP-based internal communications and information management Adds brokering, presence management and discovery capabilities to basic SOA

18. Net-Centric Validation Conference 2007 18 CEET Conference 200718 Example ESB Software Internals

19. Net-Centric Validation Conference 2007 19 CEET Conference 200719 CPN Model of a Key Presence/Discovery Component

20. Net-Centric Validation Conference 2007 20 CEET Conference 200720 Results Runtime Lab Output – Use case 1Model Output – Use case1

21. Net-Centric Validation Conference 2007 21 CEET Conference 200721 Related Modeling Efforts SOA Security SOA Compression SOA Governance SOA Granularity XMPP CPN as well as OPNET