Applying model-driven engineering for linking web service and context models

Preface. 1. Introduction. 1.1 What is COP? 1.2 Why is COP important? 1.3 What is a component? 1.4 Hardware components and software components. 1.5 From OOP to COP. 1.6 Component-based software engineering. 1.7 Summary. 1.8 Self-review questions. 1.9 Exercises. 2. A Theory of Components. 2.1 Principles of COP. 2.2 Infrastructures of COP. 2.3 Component models. 2.4 Connection models. 2.5 Deployment models. 2.6 Unifying component technologies. 2.7 Summary. 2.8 Self-review questions. 2.9 Exercises. 3. COP with JavaBeans. 3.1 Overview of JavaBeans technology. 3.2 The component model of JavaBeans. 3.3 The connection model of JavaBeans. 3.4 The deployment model of JavaBeans. 3.5 Examples and lab practice. 3.6 Summary. 3.7 Self-review questions. 3.8 Exercises. 4. Enterprise JavaBeans Components. 4.1 The EJB a rchitecture. 4.2 The component model of EJB. 4.3 The connection model of EJB. 4.4 The deployment model of EJB. 4.5 Examples and lab practice. 4.6 Summary. 4.7 Self-review questions. 4.8 Exercises. 4.9 Programming exercises. 5. CORBA Components. 5.1 The COBRA component infrastructure. 5.2 The CORBA component model (CCM). 5.3 The connection model of CORBA and CCM. 5.4 The deployment model of CORBA and CCM. 5.5 Examples and lab practice. 5.6 Summary. 5.7 Self-review questions. 5.8 Exercises. 5.9 Programming exercises. 6. .NET Components. 6.1 The .NET framework. 6.2 The component model of .NET. 6.3 The connection model of .NET. 6.4 .NET component deployments. 6.5 Visual Studio .NET. 6.6 Examples and lab practice. 6.7 Summary. 6.8 Self-review questions. 6.9 Exercises. 6.10 Programming exercises. 7. COP with OSGi Components. 7.1 Overview of OSGi technology. 7.2 The component model of OSGi. 7.3 The connection model of OSGi. 7.4 The deployment model of OSGi. 7.5 Examples and lab practice. 7.6 Summary. 7.7 Self-review questions. 7.8 Exercises. 8. Web Services Components. 8.1 The Web Services framework. 8.2 The component model of Web Services. 8.3 The connection model of Web Services. 8.4 Web Services component deployment. 8.5 Examples and lab practice. 8.6 Summary. 8.7 Self-review questions. 8.8 Exercises. 8.9 Programming exercises. Appendix.

Context-aware web services have been attracting significant attention as an important approach for improving the usability of web services. In this paper, we explore a novel approach to model dynamic behaviors of interacting context-aware web services, aiming to effectively process and take advantage of contexts and realize behavior adaptation of web services and further to facilitate the development of context-aware application of web services. We present an interaction model of context-aware web services based on context-aware process network (CAPN), which is a data-flow and channel-based model of cooperative computation. The CAPN is extended to context-aware web service network by introducing a kind of sensor processes, which is used to catch contextual data from external environment. Through modeling the register link's behaviors, we present how a web service can respond to its context changes dynamically. The formal behavior semantics of our model is described by calculus of communicating systems process algebra. The behavior adaptation and context awareness in our model are discussed. An eXtensible Markup Language-formatted service behavior description language named BML4WS is designed to describe behaviors and behavior adaptation of interacting context-aware web services. Finally, an application case is demonstrated to illustrate the proposed model how to adapt context changes and describe service behaviors and their changes.

Despite the great interest and the enormous potential, Web services, and more in general service-oriented architectures (SOAs), are still in their infancy. The speed at which software vendors have released middleware and development tools for Web services is unprecedented, but their level of maturity is still far from their counterparts in conventional middleware. This is only natural and common to any novel technology, and will be corrected over time, as more users adopt this technology and provide feedback on what the actual needs are.

The automatic composition of Web services requires the existing services to be encoded in a semantic form, such as ontology. If Web services are represented with ontology, we can automatic compose Web services by means of their semantics. Ontology modeling is divided into two steps: input/output parameters modeling and Web services modeling. First, we collect Web services' input/output parameters, represent them with classes in ontology, and transform Web services to properties in ontology, define relations between classes and properties. Then we judge Web services' relations based on relations between properties transformed from these Web services and estimate whether these Web services can be composed.

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.

Web services form the core of e-business and hence, have experienced a rapid development in the past few years. This has led to a demand for a discovery mechanism for Web services. Discovery is the most important task in the Web service model because Web services are useless if they cannot be discovered. A large number of Web service discovery systems have been developed. Universal Description, Discovery and Integration (UDDI) is a typical mechanism that stores indexes to Web services but it does not support semantics. Semantic Web service discovery systems that have been developed include systems that support matching Web services using the same ontology, systems that support matching Web services using different ontologies, and systems that support limitations of UDDI. This paper presents a survey of Web service discovery systems, focusing on systems that support semantics. The paper also elaborates on open issues relating to such discovery systems. Request access from your librarian to read this chapter's full text.

Matching web services and client requirements in the form of goals is a significant challenge in the discovery of semantic web services. The most common but unsatisfactory approach to matching is set‐based, where both the client and web services declare what objects they require and what objects they can provide. Matching then becomes the simple task of comparing sets of objects. This approach is inadequate because it says nothing about the functionality required by the client or the functionality provided by the web service. As an alternative, we use the Frame Logic as implemented in Flora‐2 to specify web service capabilities and client requirements, including their preconditions, postconditions, and ontologies, implement a logic‐based discovery agent using Flora‐2, demonstrate its usefulness in a medical appointment making scenario, and show its efficiency both theoretically and by benchmarking. The result is an expressive yet concise representation scheme for semantic web services, and a practical, efficient, powerful, and fully implemented matching engine based purely on logical inference for web service discovery, with direct applicability to Web Service Modeling Ontology and Web Service Modeling Language, because both are based on Frame Logic.

While Web service models become increasingly popular and many service providers start to offer all kinds of Web services, the quality of service (QoS) for Web services has become an important factor for service requesters to consider during the selection process of appropriate Web services. In this paper, we present an evaluation and selection framework (CosmosQoS) for QoS-required Web services. A novel architecture and reputation appraisal model to monitor, store and evaluate the physical usage and post-condition of requested Web services in a requester-located network is proposed to better support service requesters such that they can select suitable Web services based on their QoS requirements, trustworthiness of Web services, and effect of network connection and configuration between service requesters and providers.

Web services form the core of e-business and hence, have experienced a rapid development in the past few years. This has led to a demand for a discovery mechanism for web services. Discovery is the most important task in the web service model because web services are useless if they cannot be discovered. A large number of web service discovery systems have been developed. Universal Description, Discovery and Integration (UDDI) is a typical mechanism that stores indexes to web services but it does not support semantics. Semantic web service discovery systems that have been developed include systems that support matching web services using the same ontology, systems that support matching web services using different ontologies, and systems that support limitations of UDDI. This paper presents a survey of web service discovery systems, focusing on systems that support semantics. The paper also elaborates on open issues relating to such discovery systems.

Development of services that span over the Internet and Telecom networks is driving significant efforts towards the integration of services offered by Telecom operators. The telecommunications R&D community also starts adapting and developing similar service delivery platforms to offer a wide range of new value‐added services faster and more cost efficiently inspired by the success of Web service technologies for the development and deployment of IT services. In this paper, we have an analysis for Telecom Web services communication requirements and also propose Telecom Web services communication model considering the specific characteristics as state, asynchronous, event‐driven communications in Telecom domain. We focus on the design and implementation details for real‐time Web service communication model in Telecom domain, and as the framework of communication model for Telecom Web services, the enhanced state machine design and implementation, and the messages dispatching design and implementation for Telecom Web services communication model, and also illustrate the third party end call control scenarios. Finally, we give the conclusion and future essential work. Copyright © 2009 John Wiley & Sons, Ltd.

The wide deployment of Web services in wire line and wireless networks has resulted in the proliferation of user identities relying on which the trust between a user and a Web service can be established through identification and authentication. Since user identities normally contain some information concerned with user privacy, sharing of such identity information between Web services should be minimized to preserve user privacy. In this paper, we propose a user-centric trust model for supporting Web services based on the principle of least sharing identity information. This model can be applied to applications in which a user is interacting with multiple Web services simultaneously. We describe this model and show how it can be used as the foundation for developing comprehensive solutions to protect user identities during Web service interactions, thus preserving user privacy.

The recent approaches for Web services composition tend to integrate heterogeneous business processes executed in Peer-to-Peer networks. In such networks, component Web services are invoked on independent peers and are orchestrated according to the transactional requirements defined by the designers or the users of the composite Web service. Since component Web services can be dynamically invoked and are generally implemented as black boxes, concurrency between them may appear. This paper presents the transactional execution model of composite Web services exploiting the transactional properties of their component Web services. The proposed concurrency control is ensured by a decentralized serialization graph based on an optimistic protocol and on the hierarchical structure of the composition. The globally correct execution of the composite Web service is achieved by communication among dependent subtrans-actions and the peers they have accessed.

A solution of asynchronous Web Services is proposed through the analysis of Web Services' concept and architecture. And on this basis, some further discussions on how to implement the WebLogic JMS-based Asynchronous Web Services with several specific examples. It is proved that asynchronous Web Services can improve performance of application in particular case, but it is not always applicable. In practice, appropriate Web Services should be adopted according to actual situation.

<span>Web services' high levels of duplicate textual structures have caused network bottlenecks and congestion. Clustering and then aggregating similar web services as one compressed message can potentially achieve network traffic reduction. In this paper, a static Hilbert clustering as new model for clustering web services based on convex set similarity is proposed. Mathematically, the proposed model calculates similarity among simple object access protocol (SOAP) messages and then cluster them based on higher similarity values. Next, each cluster is aggregated as a compact message. The experiments have explained the proposed model performance as it has outperformed the convention clustering strategies in both compression ratio and clustering time. The best results have been achievable by the proposed model has reached up to (15) with fixed-length and up to (21) with Huffman.</span>

In this paper, we overviewed self-healing issues of Web services using AOP. This type of programming supports separation of self-healing concerns from Web services code and promotes maintenance and reusability. Similar to any computing application, Web services are subject to failure and unavailability due to multiple reasons, such as Web service faulty-code and unreliable communication-infrastructure