Optimal QoS-Aware Web Service Composition

Abstract

The availability of many independent services on an open network opens the opportunity of composing individual instances to achieve complex functionality. Most often there are several possible compositions to achieve the same highlevel functionality; the advantage of choosing one composition instead of another one may lie in the different quality of the composition, e.g., one might be cheaper, faster, or more reliable. In this paper, we focus on services described with XML documents and accessed via XML Protocols, known as Web services, and enriched with semantic and Quality of Service (QoS) annotations. We propose an algorithm that, given a desired functionality, returns a composition of services from a repository with the optimal response time or throughput. Services are composed taking into account an ontology of operation names expressed in OWL. RuGQoS is the related implementation.

Dynamic Service Composition

“…Proposed approach considers keyword match and semantic matching can be performed with very minimal changes. Result of experiment following proposed algorithm shows improvement compared to that of algorithm following FCA [10] and BCA [11] . Mathematical analysis also proves that proposed algorithm is scalable and improvement in performance increases as the length of composition plan increases and it is well supported by the result of experiments.…”

“…Backward Chaining Approach for dynamic service composition is introduced by [9] and is followed by [11]. Figure 2 shows the flow chart of BCA.…”

“…There have been a lot of researches in the area of dynamic service composition. The main issue with dynamic composition algorithm is related to the composition time taken by algorithm to generate a composite service [10], [11], [12] . Composition time indicates duration of the time at which the service request was submitted to the algorithm till the algorithm generates a composite service that can satisfy service request.…”

“…[10] And [12] mainly follow forward chaining approach (FCA) that starts from the source; explore all paths until destination is reached. Another architecture [11] that won the second best architecture award in same WSC 2009 competition follows backward chaining approach (BCA) in which algorithm starts from destination, explore all the nodes from which destination is reachable until all the explored nodes can be reached from the source. FCA and BCA are described in detail in Section III-A and Section III-B respectively.…”

WSARCH: Uma arquitetura para a provisão de web services com qualidade de serviço

“…As características de QoS tais como custo, disponibilidade, tempo de execução e reputação também são analisadas. Em (Aiello et al, 2009) é proposto um algoritmo que, dada a funcionalidade desejada, retorna uma composição de serviços a partir de um repositório com o ótimo tempo de resposta ou throughput. Os serviços são compostos, levando em consideração uma ontologia de nomes de operações expressas em Web Ontology Language (OWL).…”