Planning and Specifying the Composition of Web Services

As the Web services paradigm becomes popular and more and more applications are created and deployed as Web services, the need for developing new solutions tackling the composition of Web services becomes manifest. However, emerging web service standards and existing methods are not sufficient for realizing the goal of flexible and dynamic composition of Web services, although some preliminary work has been conducted in the area of services composition. This situation has raised the interesting research points for creating and developing new approaches for the Web services composition. In this paper we separate the design and implementation phases of the composite services, and concentrate on the research of the way a composite service is constructed in terms of its constituent services. We call this way the composition logic of a composite service. We firstly propose well-defined notions “composition structures” to represent the joints among the constituent services and generate the reliable structure of a composite service, and then we provide a specification mechanism to clearly specify the internal dependencies of a composite service in terms of the notification and dataflow dependencies. Our solutions for planning and specifying the composition of Web services can effectively support the properties of modularity, interoperability, dynamic reconfigure-ability and fault-tolerance for a composite software system in the dynamic Web environments of business applications, which are a organic part of our framework for tackling the challenges of Web service discovery and composition on which we are working

Подход к определению полноты композиции семантических Веб–сервисов

Основная задача сервис-ориентированной парадигмы – это облегчение автоматизи-рованной композиции сервисов мотивирована сценариями, развиваемыми в электронной коммерции и e-science. Проблема автоматизированной композиции начинается со спецификации цели "goal" сервиса и набора доступных для поиска сервисов. Композиция зависит от обнаружения соответствующих сервисов на семантическом уровне, в основном, через входные и выходные условия активностей, и сборки их в "приложение" целевого сервиса. Мы исследуем проблему полноты композиции, путем усиления запросов поиска сервисов, начиная от условий целевого сервиса. Более сильное условие может найти более релевантный сервис, без которого сборка целевого сервиса может быть невозможной. Проблема усиления условий изучается в различных логических языках, в данном случае, используются условия с порядковыми ограничениями.Основне завдання сервіс-орієнтированої парадигми полягає у полегшенні автоматизованої композиції сервісів яке мотивоване сценарія-ми, що розвиваються в електронній комерції і e-science. Проблема автоматизованої композиції починається із специфікації мети "goal" сервісу і визначення набору доступних сервісів для пошуку. Композиція залежить від виявлення відповідних сервісів на семантичному рівні, в основному, через вхідні і вихідні умо-ви активностей, і збірки їх в "застосування" цільового сервісу. Ми досліджуємо проблему повноти композиції, шляхом посилення запитів пошуку сервісів, починаючи від умов цільового сервісу. Сильніша умова може знайти більш релевантний сервіс, без якого збірка цільового сервісу може бути неможливою. Проблема посилення умов вивчається в різних логічних мовах, у даному випадку, використовуються умови з порядковими обмеженнями.A Basic task of the service oriented paradigm/SOA is facilitation the automated composition of services motivated by scenarios developed in electronic commerce and e-science. The problem of the automated composition is begun with the specification of "goal" service and set of accessible for a search existing services. Composition depends on finding out the proper services on semantic level, mainly, through the entry/exit conditions, and assembling them in a "application" as a purpose service. Based on this framework, we study in this paper a tightening problem which strengthens service discovery queries formulated from conditions in the goal service. A tighter condition can find more relevant services while a looser one may exclude the possibility of assembling a goal realization. The tightening problem is studied for conditions is studied in different logical languages, in this case, ones given for both integers and real numbers constraints

Evaluating performance of web services in cloud computing environment with high availability

This paper presents an methodology for attaining high availability to the demands of the web clients. In order to improve in response time of web services during peak hours dynamic allocation of host nodes will be used in this research work. As web users are very demanding: they expect web services to be quickly accessible from the world 24*7. Fast response time leads to high availability of web services, while slow response time degrades the performance of web services. With the increasing trend of internet, it becomes a part of life. People use internet to help in their studies, business, shopping and many more things. To achieve this objective LAMP platform is used which are Linux, Apache, My SQL, and PHP. LAMP is used to increase the quality of product by using open source software. The proposed strategy will work as middle layer and provide highly availability to the web clients

Integración de procesos de negocio basados en servicios Web: Coreografía y satisfacción de restricciones

Los procesos de negocio en ocasiones necesitan funcionalidades adicionales que pueden alcanzarse empleando servicios del mismo dominio o de uno externo. Durante este procedimiento, los servicios web involucrados deben integrarse, de tal forma que sus funcionalidades individuales generen un comportamiento global. La coreografía de servicios web controla la secuencia de las interacciones entre los servicios durante el proceso de integración. Este artículo presenta una aproximación al modelado basado en restricciones de la coreografía de servicios web, a fin de lograr su automatización

A Four-Level Linear Discriminant Analysis Based Service Selection in the Cloud Environment

The cloud is an outstanding platform to deal with functionally equivalent services which are exponentially increasing day-by-day. The selection of services to meet the client requirements is a subtle task. The services can be selected by ranking all the candidate services using their network and non-network Quality-of-Service (QoS) parameters, which is formulated as a NP hard optimization problem. In this paper, we proposed a linear discriminant analysis (LDA) based a four level matching model for service selection based on QoS parameters, which includes description matching of a service, matchmaking phase, LDA-based QoS matching and ranking. The LDA-service selection agent is deployed on each cloud to classify services into classes and rank the services based on the aggregate QoS value of each service. Finally, the test results show the efficiency in service selection with minimal discovery overhead, significant reduction in the computation time and the number of candidate services to be considered

Optimal QoS aware multiple paths web service composition using heuristic algorithms and data mining techniques

The goal of QoS-aware service composition is to generate optimal composite services that satisfy the QoS requirements defined by clients. However, when compositions contain more than one execution path (i.e., multiple path's compositions), it is difficult to generate a composite service that simultaneously optimizes all the execution paths involved in the composite service at the same time while meeting the QoS requirements. This issue brings us to the challenge of solving the QoS-aware service composition problem, so called an optimization problem. A further research challenge is the determination of the QoS characteristics that can be considered as selection criteria. In this thesis, a smart QoS-aware service composition approach is proposed. The aim is to solve the above-mentioned problems via an optimization mechanism based upon the combination between runtime path prediction method and heuristic algorithms. This mechanism is performed in two steps. First, the runtime path prediction method predicts, at runtime, and just before the actual composition, execution, the execution path that will potentially be executed. Second, both the constructive procedure (CP) and the complementary procedure (CCP) heuristic algorithms computed the optimization considering only the execution path that has been predicted by the runtime path prediction method for criteria selection, eight QoS characteristics are suggested after investigating related works on the area of web service and web service composition. Furthermore, prioritizing the selected QoS criteria is suggested in order to assist clients when choosing the right criteria. Experiments via WEKA tool and simulation prototype were conducted to evaluate the methods used. For the runtime path prediction method, the results showed that the path prediction method achieved promising prediction accuracy, and the number of paths involved in the prediction did not affect the accuracy. For the optimization mechanism, the evaluation was conducted by comparing the mechanism with relevant optimization techniques. The simulation results showed that the proposed optimization mechanism outperforms the relevant optimization techniques by (1) generating the highest overall QoS ratio solutions, (2) consuming the smallest computation time, and (3) producing the lowest percentage of constraints violated number

QoS-Aware Middleware for Web Services Composition

The paradigmatic shift from a Web of manual interactions to a Web of programmatic interactions driven by Web services is creating unprecedented opportunities for the formation of online Business-to-Business (B2B) collaborations. In particular, the creation of value-added services by composition of existing ones is gaining a significant momentum. Since many available Web services provide overlapping or identical functionality, albeit with different Quality of Service (QoS), a choice needs to be made to determine which services are to participate in a given composite service. This paper presents a middleware platform which addresses the issue of selecting Web services for the purpose of their composition in a way that maximizes user satisfaction expressed as utility functions over QoS attributes, while satisfying the constraints set by the user and by the structure of the composite service. Two selection approaches are described and compared: one based on local (task-level) selection of services and the other based on global allocation of tasks to services using integer programming