failure recovery of composite semantic web services using subgraph replacement
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Failure Recovery of Composite Semantic Web Services
using Subgraph Replacement
Hadi Saboohi
Amineh Amini
Hassan Abolhassani
Karaj Islamic Azad University, IRAN
Web Services
15 May 2008ICCCE’082
A software system designed to support interoperable Machine to Machine interaction over a network
Web APIs
Semantic Web
15 May 2008ICCCE’083
Extension of current web Giving well-defined meaning to information Enabling computers and people to work in
cooperation
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
Semantic Web Services, continued
15 May 2008ICCCE’085
InteroperableSyntax
InteroperableSemantics
DynamicResources
StaticResources
Web Services
WWW
Semantic Web Services
Semantic Web
Service Broker
15 May 2008ICCCE’086
Service Broker
Service Registry
Concepts Registry
Ontology Cache
Composed ServicesCache
Registry Manager
Ontology Manager
ComposerAdapterMatchmaker
ExecutorKernel
Ref. 4
Modeling Composite Semantic Web Services
15 May 2008ICCCE’087
Directed Acyclic Graph Nodes: Web Services Edges: Services inputs and outputs
1)()( GEGV
I, PA Si B
O, E
OA, EA
ISi, PSi
OSi, ESi
IB, PB
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
Replacement Strategy
15 May 2008ICCCE’089
Responsible for: Finding best substitution alternative Managing differences between old and new
service(s)
Replacement Steps
15 May 2008ICCCE’0810
1. Finding all possible alternatives a. Subgraph calculationb. Alternative search
2. Ranking alternatives3. Replacement
1. a. Subgraph calculation
15 May 2008ICCCE’0811
A S B
A S B
A S
A
S B
S
B
Composite Graph
All possible subgraphs
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 …
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
esδDifferencNewβNewβ
UndoαUndoαRank
Cost2Length1
Cost2Count1
3. Replacement
15 May 2008ICCCE’0814
First: re-execution attempts Second: Replacing best ranked subgraph
Compensation of well-executed web services in old subgraph
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
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
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