Aspect-oriented Programming for Dynamic Web Service Selection, Integration and Management

Management applications of the Web Service Offerings Language (WSOL)

Web service technology allows for the development of client applications independently of the Web services they use. In this article, we propose a dynamic invocation mechanism for unanticipated Web services that offers support for conversational messaging, based on dynamic aspect oriented programming (AOP) techniques. Aspects are used to store the communication details and the conversational context of the Web service. In case of service failures, the conversation can be replayed on another semantically equivalent Web service, in a transparent way for the client. Code examples are given in the dynamic AOP language JAsCo, and a prototype, called Web services management layer, is discussed as a proof of concept.

Summary form only given. Industry has been wrestling with the complexity of managing business systems for years. The challenge stems from the variety of application and IT resource providers that enterprises use to build their business systems. A range of management systems co-exist to manage the breadth of resources. The management industry and customers have an opportunity to take advantage of the industry trend towards using Web services for business integration and moving to service oriented architectures for business. It is now possible to garner these same advantages seen in business for management. Building manageable resources and management systems on a Web services foundation is going to cause a profound shift in how enterprises and vendors manage their IT resources in the future. Embracing this shift is going to create more flexible IT infrastructures, better integration of business and IT objectives, and greater end to end management of both IT infrastructures and business processes. This presentation provides a bottoms-up tutorial of Web services distributed management (WSDM), the new OASIS Standard that provides the first step in solving this classic management integration problem. The session will begin with an overview of the SOA based management architecture and WSDM's place in that architecture relative to other industry standards and initiatives. The technical tutorial will begin with an introduction on WSDL and WS-addressing, specifications on which WSDM depends. The presenters will build on this with an overview of the Web services for resource framework (WSRF) and Web services notification (WSN) OASIS specifications and discuss how they are used by WSDM. Finally, the session will explore WSDM components, management using WS (MUWS) and WSDM management of Web services (MOWS). MUWS defines how to represent and access the manageability interfaces of any IT resource as Web services. MOWS defines how to manage Web services as resources and how to describe and access that manageability using MUWS. Concrete customer issues solved by WSDM will also be highlighted as well as how CIM modeled resources can be accessed using WSDM. Apache MUSE and IBM Developerworks Toolkits will be used to illustrate the programming techniques

Aiming at the hot and difficult issues in Web services and service composition, this paper analyzes and studies the selection of Web services and service composition from the functional and non functional attributes of Web services, and mainly makes the following work and innovation. First of all, the functional attributes of Web services are studied, Web services on various service provision platforms are collected, and Web services are classified. Secondly, aiming at the shortcomings of existing Web service QoS attribute evaluation models, an improved method is proposed, which introduces a comprehensive evaluation mechanism of variable weight vector. Based on the constant weight comprehensive evaluation method, the state variable weight vector is established to dynamically adjust the attribute weights of various service QoS indicators, so as to improve the accuracy and objectivity of the Web service QoS attribute evaluation. Finally, in view of the defects and deficiencies of traditional algorithms in the selection of Web service composition, the particle swarm optimization algorithm with linearly decreasing inertia weight and learning factor is introduced, which better balances the self cognition and social learning ability of particles, and improves the search speed and global search ability of particles. And a large number of experiments are carried out to compare it with the traditional algorithm, which verifies the effectiveness and superiority of the improved particle swarm optimization algorithm.

Virtual enterprise is a temporary network of independent companies or enterprises that can quickly bring together to fulfill a value-added task. With the development of Web service technologies, the enterprise business systems can be encapsulated as Web services. Establishing a virtual enterprise is actually a process of Web services composition. As more and more Web services are available, many Web services with different quality of service (QoS) can be found for tasks of the composite Web service. Thus, a significant research problem in Web service composition is how to select the correct Web services for tasks such that the composite Web service gives the best overall quality. In this paper, we propose an approach to achieve Web services selection efficiently with excellent comprehensive quality. Firstly, a comprehensive evaluation model based on generic QoS (GQoS) and domain QoS (DQoS) of composite Web service is established. Secondly, a novel optimization algorithm named culture max–min ant system (C-MMAS) is constructed to solve the problem of Web service selection based on DGQoS. Simulations show that when used in Web service selection, C-MMAS is better than ant colony optimization algorithm and MMAS in efficiency.

The increasing popularity of Web services for application integration has strengthened the need for automated Web service composition and joint execution. A lot of attention has been paid recently towards techniques for creating a composite Web service from individual Web services based on user requirements, and driven by a variety of criteria. However, the major lacuna so far in Web service composition is the lack of a holistic requirements-driven approach for modeling the Web service execution lifecycle. In this paper we present such an approach based on our earlier work on context-driven Web service modeling. In particular, we separate requirements into two parts - functional and extrafunctional requirements (FRs and EFRs, respectively). We express FRs as commitments made by individual Web ser-vices towards the composite Web service, and EFRs as rules that constrain the behavior of the individual Web services while they execute against their FRs. We also present a conceptual model that can be used for tracking requirements during Web service execution.

Service Oriented Architecture (SOA) introduced the web services as distributed computing components that can be independently deployed and invoked by other services or software to execute composite services that represent an end-to-end business process. An important problem in the SOA is the web service selection and composition problem which involves selecting the right web services mix to construct the best service composition that achieves the consumers Service Level Agreement (SLA) requirements. In this chapter we propose different methods to solve the problem of the business processes execution engine web service selection and services composition construction in the Service Oriented Architecture (SOA).  The chapter provides different mechanisms to improve the web services selection and composition using dynamic techniques. The main goal is to satisfy the services' requirements expressed as the SLA and to enhance the services selection and composition by increasing the availability and decreasing the response time of the service compositions.

The increasing popularity of Web services for application integration has resulted in a large body of research on Web service composition. However, the major lacuna so far in Web service composition is the lack of a holistic requirements-driven approach for modeling the entire Web service lifecycle, i.e., composition, joint execution, midstream adaptation in response to failures or changing requirements, and finally re-execution until successful completion. In this paper we present such an approach based on our earlier work on context-driven Web service modeling. In particular, we separate requirements into two parts – functional and extra-functional requirements (FRs and EFRs, respectively). We express FRs as commitments made by individual Web services towards the composite Web service, and EFRs as rules that constrain the behavior of the individual Web services while they execute against their FRs. We also show how midstream adaptation in Web service execution – caused either by changes in user requirements or execution failures – can be managed in our approach. We believe that ours is the first such approach towards a comprehensive modeling of requirements for composite Web service executions, and especially during adaptation.

THE Internet, along with its related technologies, has created an interconnected world in which information flows easily and tasks are processed collaboratively. To make service-oriented applications more robust, Web services must be examined from a transactional perspective. By transactional, we mean first defining the actions that guide the execution of Web services when failures arise and then the states that permit claiming the success of this execution following the handling of these failures. A variety of transactional models are reported in the database community. Some of these models can be leveraged and enhanced in response to Web services characteristics while others are not suitable for Web services due to the dynamic nature of Web services, the long-running execution scenarios that Web services take part in, and the successful execution of Web services despite other peers’ failure. Today’s service-oriented applications require advanced transactional models that guarantee integrity and continuity of business processes despite the dynamic nature of the features of the environments hosting the execution of these applications. This special section sheds light on the latest advances in the fields of Web services and transactional models in order to better address advanced research on and experience with transactional Web services. Four papers out of 19 submissions were selected for inclusion in this special section. Each submission was subject to a double-review process by at least three peer reviewers. In the first paper, entitled “Event-Based Design and Runtime Verification of Composite Service Transactional Behavior,” Gaaloul et al. propose an event-driven approach to validate the transactional behavior of Web services taking part in compositions. A composition life cycle consists of four phases, namely, design, execution, monitoring, and reengineering. The verification of this behavior throughout this life cycle is done either at design time to validate recovery mechanisms’ consistency or after runtime to detect execution deviations and repair design errors, and, therefore, formally ensure the execution reliability of Web services. In addition, this verification is based on the Event Calculus formalism, which offers a sound definition for this reliability. In the second paper, entitled “FACTS: A Framework for Fault-Tolerant Composition of Transactional Web Services,” Liu et al. note that delivering reliable compositions over unreliable Web services is challenging. To address this challenge, Liu et al. identify a set of high-level exception handling strategies and a new taxonomy of transactional Web services to devise a fault-tolerant mechanism that combines exception handling and transaction techniques. In addition, Liu et al. devise two modules, known as specification and verification, to assist service designers in constructing fault handling logic conveniently and correctly. This logic is automatically injected into WS-BPEL. In the third paper, entitled “Rule-Based Coordination of Distributed Web Service Transactions,” von Riegen et al. study the distributed transactional activity control problem in the context of service choreographies. In such a context, many participants are allowed to work together to achieve a global, common goal, and the initiator of a process is not always the one who is able to commit or cancel a transaction. Von Riegen et al. introduce a framework that allows autonomous coordination of dynamic processes. This framework extends WSBusinessActivity to strengthen the role of the coordinator. Predicate rules are developed to let participants cancel or complete a process and help the coordinators decide on the completion processes and the confirmation or cancellation of the participants’ works. In the fourth paper, entitled “TQoS: Transactional and QoS-Aware Selection Algorithm for Automatic Web Service Composition,” El Haddad et al. focus on the issues of selecting and composing Web services. A design-time selection algorithm is proposed in which transactional and QoS requirements are both integrated into the selection process. This algorithm is based on the notion of risk that indicates if execution outcomes can either be compensated for or not. Two risk levels of execution in a transactional system are considered: Risk 0, meaning that if the execution is successful, the obtained outcomes can be compensated for by the user, and Risk 1, meaning that the system does not guarantee successful execution, but if it achieves it, the outcomes cannot be compensated for by the user. We hope this special section inspires researchers to develop new transactional models that would guarantee service-oriented applications integrity and continuity. 30 IEEE TRANSACTIONS ON SERVICES COMPUTING, VOL. 3, NO. 1, JANUARY-MARCH 2010

Web services composition is a process of creating a new web service from a set of available web services. Semi-dynamic web services composition in Service Oriented Architecture (SOA) consists of designing composition plan by service provider, and automation of web service discovery and selection at runtime. This research paper describes redundant-free web services composition in order to reduce execution time and overall cost of the composition process and also improve efficiency of the composition method. To fulfill the needs, this paper uses a linked list data structure called Composition List (CL) to select the ideal services. In addition, a hash table called Available Output Parameters (AOP) is used to find redundant web services and reject them from web services composition process.

A web service is an interface of the software component that can be accessed by standard Internet protocols. The web service technology enables an application to application communication and interoperability. The increasing number of web service providers throughout the globe have produced numerous web services providing the same or similar functionality. This necessitates the use of tools and techniques to search the suitable services available over the Web. UDDI (universal description, discovery and integration) is the first initiative to find the suitable web services based on the requester's functional demands. However, the requester's requirements may also include non-functional aspects like quality of service (QoS). In this paper, the authors define a QoS model for QoS aware and business driven web service publishing and selection. The authors propose a QoS requirement format for the requesters, to specify their complex demands on QoS for the web service selection. The authors define a tree structure called quality constraint tree (QCT) to represent the requester's variety of requirements on QoS properties having varied preferences. The paper proposes a QoS broker based architecture for web service selection, which facilitates the requesters to specify their QoS requirements to select qualitatively optimal web service. A web service selection algorithm is presented, which ranks the functionally similar web services based on the degree of satisfaction of the requester's QoS requirements and preferences. The paper defines web service provider qualities to distinguish qualitatively competitive web services. The paper also presents the modelling and selection mechanism for the requester's alternative constraints defined on the QoS. The authors implement the QoS broker based system to prove the correctness of the proposed web service selection mechanism.

The trustworthiness between anonymous web service client and provider influences service stability and collaboration. Trustworthiness includes some aspects such as service's security, controllability and survivability. So, a definition of trustworthiness for web service is given in the paper, and then a web service trustworthiness evaluation and management model is brought forth inspired by human small-world network. The model consists of three web service federations: WSRRC, APAEAS and AWSORT. WSRRC is a Web Service Resource Register Center, which is established by UDDI protocol. APAEAS is an Area Proxy Authentication Evaluating Autonomy System, which collects some authentication information of web service clients, accepts clients' special requirement and feedbacks service's trustworthiness values to AWSORT. AWSORT is an Area WS Resource Organizing Tree, which organizes and manages web service resources; records web service trustworthiness values, keeps web service state, assigning web service. The model establishes a trustworthy environment for anonymous web service clients and providers. Furthermore, some detailed evaluating parameters about service trustworthiness and quality is discussed and some service management algorithms are proposed in the paper. The simulation results show that model is feasible for semantic grid integration and establishment for virtual organization.

In the Web Service Composition (WSC) domain, Web Services (WSs) execute in a highly dynamic environment, as a result, the Quality of Service (QoS) of a WS is constantly evolving, and this requires tracking of the global optimization overtime to satisfy the users’ requirements. In order to make a WSC adapt to such QoS changes of WSs, we propose a self-healing model for WSC. Self-healing is the automatic discovery, and healing of the failure of a composite WS by itself due to QoS changes without interruption in the WSC and any human intervention. To the best of our knowledge, almost all the existing self-healing models in this domain substitute the faulty WS with an equivalent one without paying attention to the WS selection processes to achieve global optimization. They focus only on the WS substitution strategy. In this paper, we propose a self-healing model where we use our hybrid approach to find the optimal WSC by using Parallel Genetic Algorithm based on Q-learning, which we integrate with K-means clustering (PGAQK). The components of this model are organized according to IBM’s Monitor, Analyse, Plan, Execute, and Knowledge (MAPE-K) reference model. The PGAQK approach considers as a module in the Execute component. WS substitution strategy has also been applied in this model that substitutes the faulty WS with another equivalent one from a list of candidate WSs by using the K-means clustering technique. K-means clustering is used to prune the WSs in the search space to find the best WSs for the environment changes. We implemented this model over the NET Framework using C# programming language. A series of comparable experiments showed that the proposed model outperforms improved GA to achieve global optimization. Our proposed model also can dynamically substitute the faulty WSs with other equivalent ones in a time-efficient manner

Web services provide a promising solution to an age old need of fast and flexible information sharing among people and businesses. One of the key research issues in web services is selection of most pertinent web services. Selection of web service has become a tedious job because of the increasing number of service providers providing services with similar functionality. Therefore, a framework for selection and discovery of web service that can meet the non-functional requirements is needed. In this work, we have developed a selection tool (WSS-NFP) for web services which can rank services based on their non functional properties such as performance, delay etc. We have used soft computing techniques for selection and discovery of web services based on non functional properties. These properties are fuzzy in nature. A tool is developed and implemented that is generic in nature and can be customized for any application domain. As a core of this tool, it consists of Fuzzy System for ranking web services and Neural Network for fine tuning the membership functions for linguistic terms. Appropriate and fine tuned membership functions help in minimizing the output error measure and maximizing the performance index of the proposed tool. This tool is basically a Neuro-Fuzzy system for ranking web services of any domain.

Conventional web services have more minor role of semantics for finding appropriate web services. In semantic web service selection, the maximum matching process plays an important role in finding accurate results using semantics. Most of the pre-existing web service selection approaches work based on keyword-based searching to find the relevant results for the corresponding user query. These approaches neglect the semantic understanding, which leads to irrelevant results for a user query. This paper reviews existing state-of-the-art for semantic web service selection. The techniques discussed here focused on the semantic capabilities and are also applicable for both web service composition and web service selection. Furthermore, two network flow-based approaches for maximum matching are applied, and an improvement in web service selection is observed.