Web Services World Research Articles

Introducing test data-set for the QoS-aware web-services discovery and composition

The QoS-aware web services discovery and composition are considered as two important, open and hot issues in Service-Oriented Architecture (SOA). By definition, web-service discovery is about how to select the best web-service for a role in a workflow among available web-services whereas web-services composition works on developing merely optimum coordination among a number of available web-services to provide a new composed web-service intended to satisfy some users requirements for which a single web service is not (good) enough. The criteria, upon which the web service selection, position, and composition processes are based, may or may not cover the Quality of services (QoS) parameters. The latter case would turn the name of the job into QoS-aware web services discovery and composition. In this article, the QoS-WSC test data-set is introduced for the QoS-aware web-services discovery and composition with regard to specific potentials and needs of the web-services world. In this respect, at first, an interface has been designed to define QoS for the roles attended in a service-oriented architecture. Then a solution, which allows comparison among web-services through the calculation of similarity of the request to amounts of the QoS parameters of available web services, is proposed. The similarity is obtained using the internal multiplication of two vectors of weighted numerical parameters representing request parameters and QoS parameters of available web services. The weights are technically significant coefficients, which can be obtained from the QoS-WSC data-set, which is assembled out of a rule-based integration of two well-known prior data sets in the field of web services.

Web service recommendation based on time‐aware users clustering and multi‐valued QoS prediction

SummaryWith the growing number of functionally similar services over the Internet, recommendation techniques become a natural choice to cope with the challenging task of optimal service selection, and to help consumers satisfy their needs and preferences. However, most existing models on service recommendation are static, while in the real world, the perception and popularity of Web services may continually change. Time is becoming an increasingly important factor in recommender systems since time effects influence users' preferences to a large extent. In order to help users with this problem, we propose a time‐aware Web service recommendation system. First, we use K‐means clustering method in order to exclude the less similar users, which share few common Web services with the active user at different times. Slope One algorithm is also adopted in order to deal with data sparsity problem by predicting the missing ratings over time. Then, a recommendation algorithm is presented in order to recommend the top‐rated Web services. Experiments proved the accuracy of our approach compared to five existing solutions.

An evolutionary clustering approach based on temporal aspects for context-aware service recommendation

Over the last years, recommendation techniques have emerged to cope with the challenging task of optimal service selection, and to help consumers satisfy their needs and preferences. However, most existing models on service recommendation only consider the traditional user-service relation, while in the real world, the perception and popularity of Web services may depend on several conditions including temporal, spatial and social constraints. Such additional factors in recommender systems influence users’ preferences to a large extent. In this paper, we propose a context-aware Web service recommendation approach with a specific focus on time dimension. First, K-means clustering method is hybridized with a multi-population variant of the well-known Particle Swarm Optimization (PSO) in order to exclude the less similar users which share few common Web services with the active user in specific contexts. Slope One method is, then, applied to predict the missing ratings in the current context of user. Finally, a recommendation algorithm is proposed in order to return the top-rated services. Experimental studies confirmed the accuracy of our recommendation approach when compared to three existing solutions.

Time‐aware service recommendation: Taxonomy, review, and challenges

SummaryNowadays, a huge number of available Web services offer the same functionalities and a high quality of service, which makes the selection of suitable services a difficult task. In such situation, the services must be differentiated by additional criteria such as users' ratings. To meet this goal, recommendation techniques become a natural choice to cope with the challenging task of optimal service selection and to help consumers satisfy their needs and preferences. However, most existing models on service recommendation are static, whereas in the real world, the perception and popularity of Web services may continually change, and users' preferences and habits also shift frequently. Time is becoming an increasingly important factor in recommender systems, since time effects influence users' preferences to a large extent. In addition, quality‐of‐service performance of Web services is strongly linked to the service status and network environments, which are variable against time. Recently, a wide range of service recommendation approaches, dealing with the time dimension in user modeling and recommendation strategies, have been proposed. Thus, the purpose of this survey is to present a comprehensive study and analysis of the state‐of‐the‐art on time‐aware service recommendation. We identify the techniques used in recommender systems to provide the best services. Moreover, we present a classification of time‐aware recommender systems based on the target recommendation time, the type of relationship between users, and the type of feedback. Besides, we present a comparison between time‐aware recommendation approaches, and we discuss their advantages and disadvantages. Finally, challenges and requirements of time‐aware service recommendation as well as the future directions are identified according to the studied approaches.

A survey on trust and reputation models for Web services: Single, composite, and communities

Web service selection constitutes nowadays a major challenge that is still attracting the research community to work on and investigate. The problem arises since decision makers (1) cannot blindly trust the service or its provider, and (2) ignore the environment within which the service is operating. The fact that no security mechanism is applicable in such a completely open environment, where identities can be easily generated and discarded makes social approaches such as trust and reputation models appealing to apply in the world of Web services. This survey classifies and compares the main findings that contributed in solving problems related to trust and reputation in the context of Web services. First, a high-level classification scheme partitions Web services into three main architectures: single, composite, and communities. Thereafter, a low-level classification within each architecture categorizes the trust and reputation models according to the technique used to build the trust value. Based on this classification, a profound analysis describing the advantages and shortcomings of each class of models is presented; leading to uncover possible topics that need further study and investigation. In particular, we discuss the challenging problem of having active malicious Web services in the composite and community-based architectures. Thus, the paper can be used by the future researchers as a roadmap to explore new trust and reputation models for Web services taking into account the shortcomings of the existing models.

Model Checking Semantically Annotated Services

Model checking is a formal verification method widely accepted in the web service world because of its capability to reason about service behavior at process level. It has been used as a basic tool in several scenarios such as service selection, service validation, and service composition. The importance of semantics is also widely recognized. Indeed, there are several solutions to the problem of providing semantics to web services, most of them relying on some form of Description Logic. This paper presents an integration of model checking and semantic reasoning technologies in an efficient way. This can be considered the first step toward the use of semantic model checking in problems of selection, validation, and composition. The approach relies on a representation of services at process level that is based on semantically annotated state transition systems (asts) and a representation of specifications based on a semantically annotated version of computation tree logic (anctl). This paper proves that the semantic model checking algorithm is sound and complete and can be accomplished in polynomial time. This approach has been evaluated with several experiments.

XML Data Services

In this paper, we address the question, “In the brave new world of Web services and service-oriented architectures (SOA), how does data fit in?” We bring data modeling concepts to bear on the world of services, yielding an approach in which enterprise data access is handled by a collection of interrelated data services. We show how the approach can be realized on a foundation of XML standards, namely XML Schema, Web services, and XQuery. We show that this approach provides a uniform and declarative framework for integrating enterprise data assets that are drawn from disparate underlying sources, including both queryable and non-queryable data sources as well as data that is encapsulated by Web services. We also explain how the approach yields data services that are easily and efficiently reusable.

Security in a Web services world

We are getting closer to the time when Web Services will be adopted for real-life applications. Acceptance of this new concept has been slowed partly because of the security dilemmas that Web Services poses. Web Services demands an altogether different approach to security thinking - in fact it makes conventional security methods irrelevant.

Using advanced transaction meta‐models for creating transaction‐aware web service environments

Recently, the software industry has published several proposals for transactional processing in the Web service world. Even though most proposals support arbitrary transaction models, there exists no standardized way to describe such models. This paper describes potential impacts and use cases of utilizing advanced transaction meta‐models in the Web service world and introduces two suitable meta‐models for defining arbitrary advanced transaction models. In order to make these meta‐models more usable in Web service environments, they had to be enhanced, and XML representations of the enhanced models had to be developed.

Agent-based Semantic Web Services

The Web Services world consists of loosely-coupled distributed systems which adapt to changes by the use of service descriptions that enable ad-hoc, opportunistic service discovery and reuse. At present, these service descriptions are semantically impoverished, being concerned with describing the functional signature of the services rather than characterising their meaning. In the Semantic Web community, the DAML Services effort attempts to rectify this by providing a more expressive way of describing Web Services using ontologies. However, this approach does not separate the domain-neutral communicative intent of a message (considered in terms of speech acts) from its domain-specific content, unlike similar developments from the multi-agent systems community. We describe our experiences of designing and building an ontologically motivated Web Services system for situational awareness and information triage in a simulated humanitarian aid scenario. In particular, we discuss the merits of using techniques from the multi-agent systems community for separating the intentional force of messages from their content, and the implementation of these techniques within the DAML Services model.

Agent-Based Semantic Web Services

The Web Services world consist of loosely-coupled distributed systems which adapt to changes by the use of service descriptions that enable ad-hoc, opportunistic service discovery and reuse. At present, these service descriptions are semantically improverished, being concerned with describing the functional signature of the services rather than characterising their meaning. In the Semantic Web community, the DAML Services effort attempts to rectify this by providing a more expressive way of describing Web services using ontologies. However, this approach does not separate the domain-neutral communicative intent of a message from its domain-specific content, unlike similar developments from the multi-agent systems community. We describe our experiences of designing and building an ontologically motivated Web Services system for situational awareness and information triage in a simulated humanitarian aid scenario. In particular, we discuss the merits of using techniques from the multi-agent systems community for separating the intentional force of messages from their content, and the implementation of these techniques within the DAML Services model.