Download Composing semantic Web services under constraints

Composing semantic Web
services under constraints
E.Karakoc, P.Senkul
Journal: Expert Systems with Applications
36 (2009)
Outline
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Introduction
Motivating example
Related work
Composite Web Service framework (CWSF)
Modeling the composition
Plan generation
Experiments
Conclusion
I. Introduction
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A Composite Web service
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A process consisting of collaborating
heterogeneous Web service.
Dynamic
Heterogeneous
Distributive
I. Introduction (cont.)
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The reason of complexity
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Search
A number of services available over the Web
Dynamic
up-to-date information
Select
Achieve the composition goal and Qos requirement
Constraint
defines how the services will be selected.
I. Introduction (cont.)
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The author’s work
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A constraint programming based approach
for Web service composition problem.
The aim:
to generate solutions to find
executable schedules by solving constraint.
I. Introduction (cont.)
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The properties:
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How to model Qos requirements on the
composition Web service
A unified framework (CWSF)
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Transformation  a constraints satisfaction
problem
Constraint solver  composition plan
Semantic matching
II. Motivating example
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Travel Planner system
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Flight booking
Travel booking
Accommodation booking
Car rental
Free activity planning
II. Motivating example (cont.)
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User constraints:
For example: max budget≤2500$
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The goal of CWSF :
to organize the travel by selecting the
concrete services for abstract service
templates based on the user constraints.
III. Related work
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The previous work
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Composition is pre-defined
The service discovery without considering
constraint on the composition service.
Constraint optimizer:
linear programming solver
The difference:
convert both composite flow model and
users constraints into constraint satisfaction
problem
IV. Composite Web Service
framework (CWSF)
IV. CWSF (Cont.)
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CWSF designer
model the flow structure of the composite service
and constraints on the GUI
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Semantic domain model repository and semantic
inference engine
to keep the activities and their relationships in a
given domain
Service matching/mapping engine and service registry
 Use it semantic wrapper to communicate with UDDI
Registry
 To obtain the list of candidate Web services
 To reduce the candidates by checking semantic
matching
IV. CWSF (Cont.)
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Service query engine
Gather information such as the cost, price
etc. of the services, form candidate Web
services
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Plan generator
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Constraint translator
Solution analyzer
V. Modeling the composition
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Modeling the composition flow
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Composite Web service Language (CWSL)
GUI : a nested block structure
Basic blocks structures for CWSL
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Start Block
End Block
Sequential Block
And Block
Or Block
Xor Block
Iteration Block
Decision Block
Web Service Template Block
Transition
V. Modeling the composition
(cont.)
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Modeling the constraints
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Temporal and causality constraints
Service selection constraints
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Logical constraints
If/Then constraints
Control constraints
Modeling abstract services
VI. Plan generation
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to create the composition plans that
satisfy all constraint and flow structure
requirements.
Constraint engine
The constraint solver Choca,
A Java library, which conform to GPL, for
constraint satisfaction problems (CSP)
VI. Plan generation (cont.)
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Constraint translator
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Translating the flow model
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Sequential block
OR block
XOR block
Iteration and decision blocks
Translating the constraints
VI. Plan generation (cont. )
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Solution analyzer
Converting final plan into executable
service
 BPEL4WS
VII. Experiments
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The effect of increasing number of
candidate services
The effect of flow model complexity
(increasing number of blocks)
The effect of number of
variables/constraints
VIII. Conclusion
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The approach
Motivation
Method
Result