عنوان مقاله [English]
The growth of Information and Communication Technology (ICT) has significantly
increased the number of automated web services. Web services are self-contained, modular and distributed piece of software that can be described, published, located, or invoked over the network to create products, processes, and supply chains based on Service Oriented Architecture (SOA). Usually, web services are different in both functional and non-functional (or quality of service) requirements. While functional requirement states what a typical service performs, non-functional requirement states how a service addresses its task. Besides, cloud computing has provided unprecedented opportunities for hosting, developing, publishing, and applying web services. Hence, we are faced with many unique services provided with similar functionality and different Quality of Service (QoS) parameters. Therefore, an efficient service composition is required while providing necessary QoS and user constraints (known as Service Level Agreement). Most of the studies in the literature address service composition problem using QoS values announced by providers (known as advertised QoS values). However, when the services are physically deployed and invoked by service consumer, the values of QoS parameters may vary largely depending on different factors such as network
load, number of applications running in the server, and topology changes in network. To address this limitation, in this paper, we present a novel approach based on user observations. The proposed approach considers users' observation in the composition process to overcome the problem of varying QoS values in users-side. The proposed method is implemented using Floyd algorithm and
evaluated using real dataset.