Hierarchical constraint logic programming
Hierarchical constraint logic programming
IEEE Internet Computing
Building Reliable Web Services Compositions
Revised Papers from the NODe 2002 Web and Database-Related Workshops on Web, Web-Services, and Database Systems
Quality driven web services composition
WWW '03 Proceedings of the 12th international conference on World Wide Web
A model for web services discovery with QoS
ACM SIGecom Exchanges
QoS computation and policing in dynamic web service selection
Proceedings of the 13th international World Wide Web conference on Alternate track papers & posters
QoS Aggregation for Web Service Composition using Workflow Patterns
EDOC '04 Proceedings of the Enterprise Distributed Object Computing Conference, Eighth IEEE International
Constraint Driven Web Service Composition in METEOR-S
SCC '04 Proceedings of the 2004 IEEE International Conference on Services Computing
Business Rules Integration in BPEL " A Service-Oriented Approach
CEC '05 Proceedings of the Seventh IEEE International Conference on E-Commerce Technology
Using constraint hierarchies to support QoS-guided service composition
ICWS '06 Proceedings of the IEEE International Conference on Web Services
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A key impediment to the widespread adoption of web services is the relatively limited set of tools available to deal with Quality-of-Service (QoS) factors. QoS factors pose several difficult challenges in how they may be articulated. While the functional requirements of a service can be represented as predicates to be satisfied by the target system, QoS factors are effectively statements of objectives to be maximized or minimized. QoS requirements occur naturally as local specifications of preference. Dealing with QoS factors is therefore a multi-objective optimization problem. In effect, these objectives are never fully satisfied, but satisficed to varying degrees. In evaluating alternative design decisions, we need to trade-off varying degrees of satisfaction of potentially mutually contradictory non-functional requirements. One key contribution of this work is the use of the Hierarchical Constraint Logical Programming (HCLP) framework in dealing with functional requirements, business process rules and Quality of Service (QoS) factors. We show how functional requirements and business process rules can be defined as hard constraints, QoS factors can be formulated as soft constraints and how the machinery associated with constraint hierarchies can be used to evaluate the alternative trade-offs involved in seeking to satisfy a set of QoS factors that might pull in different directions. We apply also this approach to the problem of reasoning about web service selection and composition, and establish that significant value can be derived from such an exercise.