An Optimal and Complete Algorithm for Automatic Web Service Composition

2012 ◽  
Vol 9 (2) ◽  
pp. 1-20 ◽  
Author(s):  
Pablo Rodriguez-Mier ◽  
Manuel Mucientes ◽  
Juan C. Vidal ◽  
Manuel Lama

The ability of web services to build and integrate loosely-coupled systems has attracted a great deal of attention from researchers in the field of the automatic web service composition. The combination of different web services to build complex systems can be carried out using different control structures to coordinate the execution flow and, therefore, finding the optimal combination of web services represents a non-trivial search effort. Furthermore, the time restrictions together with the growing number of available services complicate further the composition problem. In this paper the authors present an optimal and complete algorithm which finds all valid compositions from the point of view of the semantic input-output message structure matching. Given a request, a service dependency graph which represents a suboptimal solution is dynamically generated. Then, the solution is improved using a backward heuristic search based on the A* algorithm which finds all the possible solutions with different number of services and runpath. Moreover, in order to improve the scalability of our approach, a set of dynamic optimization techniques have been included. The proposal has been validated using eight different repositories from the Web Service Challenge 2008, obtaining all optimal solutions with minimal overhead.

Author(s):  
Arion de Campos Jr. ◽  
Aurora T. R. Pozo ◽  
Silvia R. Vergilio

The Web service composition refers to the aggregation of Web services to meet customers' needs in the construction of complex applications. The selection among a large number of Web services that provide the desired functionalities for the composition is generally driven by QoS (Quality of Service) attributes, and formulated as a constrained multi-objective optimization problem. However, many equally important QoS attributes exist and in this situation the performance of the multi-objective algorithms can be degraded. To deal properly with this problem we investigate in this chapter a solution based in many-objective optimization algorithms. We conduct an empirical analysis to measure the performance of the proposed solution with the following preference relations: Controlling the Dominance Area of Solutions, Maximum Ranking and Average Ranking. These preference relations are implemented with NSGA-II using five objectives. A set of performance measures is used to investigate how these techniques affect convergence and diversity of the search in the WSC context.


2015 ◽  
Vol 24 (01) ◽  
pp. 1450015 ◽  
Author(s):  
Ourania Hatzi ◽  
Mara Nikolaidou ◽  
Dimitris Vrakas ◽  
Nick Bassiliades ◽  
Dimosthenis Anagnostopoulos ◽  
...  

Web service composition is a significant problem as the number of available web services increases; however, manual composition is not an efficient option. Automated web service composition can be performed using AI Planning techniques, utilizing descriptions of available atomic web services, enhanced with semantic awareness and relaxation. This paper discusses a unified, semantically aware approach, handling both semantic (OWL-S & SAWSDL) and non-semantic (WSDL) web service descriptions. In the first case, ontology analysis is adopted to semantically enhance the planning domains and problems, in order to deal with cases where exact syntactic input-to-output matching is not feasible. In the non-semantic descriptions case, semantic information is acquired utilizing alternative sources such as lexical thesauri. Concept similarity measures are applied and utilized to achieve the desired degree of semantic relaxation. The solution to a web service composition problem is a plan describing the desired composite service. To support the proposed approach, the PORSCE framework has been implemented. The framework is modular, integrating discrete web service description languages and semantic relaxation techniques. Based on the similarity measures suggested in the paper, performance issues are also explored.


2010 ◽  
pp. 193-221 ◽  
Author(s):  
Enrico Pontelli ◽  
Tran Cao Son ◽  
Chitta Baral

This chapter presents a comprehensive logic programming framework designed to support intelligent composition of Web services. The underlying model relies on the modeling of Web services as actions, each described by a logic programming theory. This view allows the use of logic-based planning to address the Web service composition problem, taking advantage of the fact that logic-based planning enables the elegant introduction of a number of extensions and generalizations (e.g., dealing with incomplete knowledge and preferences). The theory describing each Web service is encoded as a logic programming module, and different semantics are allowed within different modules, thus better reflecting the practical use of different service description formalisms and ontologies.


2011 ◽  
pp. 355-378
Author(s):  
Enrico Pontelli ◽  
Tran Cao Son ◽  
Chitta Baral

This chapter presents a comprehensive logic programming framework designed to support intelligent composition of Web services. The underlying model relies on the modeling of Web services as actions, each described by a logic programming theory. This view allows the use of logic-based planning to address the Web service composition problem, taking advantage of the fact that logic-based planning enables the elegant introduction of a number of extensions and generalizations (e.g., dealing with incomplete knowledge and preferences). The theory describing each Web service is encoded as a logic programming module, and different semantics are allowed within different modules, thus better reflecting the practical use of different service description formalisms and ontologies.


Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Junwen Lu ◽  
Guanfeng Liu ◽  
Keshou Wu ◽  
Wenjiang Qin

Web service composition is widely used to extend the function of web services. Different users have different requirements of QoSs (Quality of Services) making them face many problems. The requirement of a special QoS may be a hard requirement or a soft requirement. The hard requirement refers to the QoS which must be satisfied to the user, and the soft one means that the requirement is flexible. This paper tries to solve the service composition problem when there are two kinds of requirements of QoSs. To satisfy various kinds of requirement of the QoS, we propose a composition method based on our proposed framework. We give an analysis from composition models of services and from related QoE (Quality of Experience) of web services. Then, we rank the service candidates and the service requests together. Based on the ranking, a heuristics is proposed for service selection and composition-GLLB (global largest number of service requests first, local best fit service candidate first), which uses “lost value” in the scheduling to denote the QoE. Comparisons are used to evaluate our method. Comparisons show that GLLB reduces the value of NUR (Number of Unfinished service Requests), FV (Failure Value), and AFV (Average Failure Value).


2021 ◽  
Vol 9 (2) ◽  
pp. 65-70
Author(s):  
Laishram Jenny Chanu ◽  
◽  
Arnab Paul ◽  

Lots of Web Services are available which differ in their QoS values but can perform a similar task. Discovery mechanism selects the best Web Service according to their QoS values and functional attributes. Cases arise, where the discovery mechanism fails, as a user’s complex query cannot be satisfied by a single Web Service. This can be solved by Web Service composition where multiple Web Services are combined to give a composite Web Service which meet user’s complex query. Our work is mainly focused on composition of Web Services that efficiently meets the user’s query. Different algorithms have been discussed and used by different researchers in this field. One of the most blooming topics is the use of evolutionary algorithms in optimization problems. In our work, we have chosen Particle Swarm Optimization Algorithm approach to discover the best efficient composition. Then, Weight Improved Particle Swarm Optimization Algorithm is used to improve the results which were found to be quite satisfying and efficient.


Author(s):  
Manuel Palomo-Duarte

Web services are changing software development thanks to their loosely coupled nature and simple adoption. They can be easily composed to create new more powerful services, allowing for large programming systems. Verification and validation techniques try to find defects in a program to minimize losses that its malfunction could cause. Although many different approaches have been developed for “traditional” program testing, none of them have proven definitive. The problem is even more challenging for new paradigms like web services and web service compositions, because of their dynamic nature and uncommon web service-specific instructions. This chapter surveys the different approaches to web service and web service composition verification and validation, paying special attention to automation. When no tools are available for a given technique, academic efforts are discussed, and challenges are presented.


2011 ◽  
pp. 739-758 ◽  
Author(s):  
Seog-Chan Oh ◽  
Dongwon Lee

In this article, a novel benchmark toolkit, WSBen, for testing web services discovery and composition algorithms is presented. The WSBen includes: (1) a collection of synthetically generated web services files in WSDL format with diverse data and model characteristics; (2) queries for testing discovery and composition algorithms; (3) auxiliary files to do statistical analysis on the WSDL test sets; (4) converted WSDL test sets that conventional AI planners can read; and (5) a graphical interface to control all these behaviors. Users can finetune the generated WSDL test files by varying underlying network models. To illustrate the application of the WSBen, in addition, we present case studies from three domains: (1) web service composition; (2) AI planning; and (3) the laws of networks in Physics community. It is our hope that WSBen will provide useful insights in evaluating the performance of web services discovery and composition algorithms. The WSBen toolkit is available at: http://pike.psu.edu/sw/wsben/.


2014 ◽  
Vol 11 (2) ◽  
pp. 67-84 ◽  
Author(s):  
Tanveer Ahmed ◽  
Abhishek Srivastava

Service oriented architecture has revolutionized the way a traditional business process is executed. The success of this architecture is Indue to the composition of multiple heterogeneous services at runtime. Web service composition is a mechanism where several web services are combined at runtime to build a complex application for a user. It is one of the most sought after processes in the context of semantic web. But, composition of web services at runtime is a difficult task owing to the availability of multiple service providers offering the same functionality. The process if exasperated by due conflicting preferences of a service consumer. In this paper, the authors address the issue of selecting a service based on Quality of Service (QoS) attributes. They utilize concepts customized from physics to create an environment that facilitates the selection of a best service from the set of similar services. The technique not only facilitates the selection of the service with the best QoS attributes, but distributes the load among expeditiously. Here in this paper, the authors concentrate on minimizing and equitably balancing the waiting time for a user. They conduct in silico experiments on multiple workflows to demonstrate the efficacy of the proposed technique to balance load efficiently among similar service offerings.


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