1. Failure Recovery of Composite Semantic Web Services using Subgraph Replacement Hadi Saboohi Amineh Amini Hassan Abolhassani Karaj Islamic Azad University, IRAN

2. Web Services 15 May 2008ICCCE’082  A software system designed to support interoperable Machine to Machine interaction over a network  Web APIs

3. Semantic Web 15 May 2008ICCCE’083  Extension of current web  Giving well-defined meaning to information  Enabling computers and people to work in cooperation

4. Semantic Web Services 15 May 2008ICCCE’084  Semantically marked-up software resources that can be published, discovered, composed and executed across the Web in a task driven semi-automatic way  Dynamic part of the semantic web

5. Semantic Web Services, continued 15 May 2008ICCCE’085 Interoperable Syntax Interoperable Semantics Dynamic Resources Static Resources Web Services WWW Semantic Web Services Semantic Web

6. Service Broker 15 May 2008ICCCE’086 Service Broker Service Requester Service Registry Concepts Registry Ontology Cache Composed Services Cache Registry Manager Ontology Manager ComposerAdapterMatchmaker Executor Kernel Service Providers Ref. 4

7. Modeling Composite Semantic Web Services 15 May 2008ICCCE’087  Directed Acyclic Graph  Nodes: Web Services  Edges: Services inputs and outputs I, P A SiSi B O, E O A, E A I Si, P Si O Si, E Si I B, P B

8. Execution problem of a composite semantic web service 15 May 2008ICCCE’088  Execution of whole process depends on well-execution of all sub-processes  In execution failure of any constitutive web service, failure recovery is a better solution  Our approach  Replace a sequence of web services containing failed service in case a “same skilled” one is not exists

9. Replacement Strategy 15 May 2008ICCCE’089  Responsible for:  Finding best substitution alternative  Managing differences between old and new service(s)

10. Replacement Steps 15 May 2008ICCCE’0810 1. Finding all possible alternatives a. Subgraph calculation b. Alternative search 2. Ranking alternatives 3. Replacement

11. 1. a. Subgraph calculation 15 May 2008ICCCE’0811 ASBASBASASBSB Composite Graph All possible subgraphs

12. 1. b. Alternative search 15 May 2008ICCCE’0812  Search for compatible replacement alternatives  Compatibility  Functional attributes (Inputs, Outputs, Effects and Preconditions)  Non-functional  Response time  Availability  Reliabiity  Cost  …

13. 2. Ranking alternatives 15 May 2008ICCCE’0813  Each constitutive web service may exist in more than one subgraph  For example: S is in four subsets of subgraphs ({S}, {A,S}, {S,B}, {A,S,B})  Each subgraph may have several alternatives

14. 3. Replacement 15 May 2008ICCCE’0814  First: re-execution attempts  Second: Replacing best ranked subgraph  Compensation of well-executed web services in old subgraph

15. Replacement Patterns 15 May 2008ICCCE’0815  Managing differences between old and new subgraphs  New subgraph may have additional IOPE(s) than old one and vice versa  Prepare required inputs and preconditions  Mark the composite as non-optimized and inspect to execute without additional outputs and effects

16. Conclusion and Future Works 15 May 2008ICCCE’0816  Alleviate failure of software systems (CSWS)  Replacing a sequence of web services  Using forward and backward mechanisms  Heuristic algorithms to decrease number of subgraphs  Extend for all composition graphs