The Service-Oriented Architecture (SOA) has become one of the most popular approaches to building large-scale network applications. The web service technologies are de facto the default implementation for SOA. Simple Object Access Protocol (SOAP) is the key and fundamental technology of web services. Service composition is a way to deliver complex services based on existing partner services. Service orchestration with the support of Web Services Business Process Execution Language (WSBPEL) is the dominant approach of web service composition. WSBPEL-based service orchestration inherited the issue of interoperability from SOAP, and it was furthermore challenged for performance, scalability, reliability and modifiability. I present an architectural approach for service composition in this thesis to address these challenges. An architectural solution is so generic that it can be applied to a large spectrum of problems. I name the architectural style RESTful Service Composition (RSC), because many of its elements and constraints are derived from Representational State Transfer (REST). REST is an architectural style developed to describe the architectural style of the Web. The Web has demonstrated outstanding interoperability, performance, scalability, reliability and modifiability. RSC is designed for service composition on the Internet. The RSC style is composed on specific element types, including RESTful service composition client, RESTful partner proxy, composite resource, resource client, functional computation and relaying service. A service composition is partitioned into stages; each stage is represented as a computation that has a uniform identifier and a set of uniform access methods; and the transitions between stages are driven by computational batons. RSC is supplemented by a programming model that emphasizes on-demand function, map-reduce and continuation passing. An RSC-style composition does not depend on either a central conductor service or a common choreography specification, which makes it different from service orchestration or service choreography. Four scenarios are used to evaluate the performance, scalability, reliability and modifiability improvement of the RSC approach compared to orchestration. An RSC-style solution and an orchestration solution are compared side by side in every scenario. The first scenario evaluates the performance improvement of the X-Ray Diffraction (XRD) application in ScienceStudio; the second scenario evaluates the scalability improvement of the Process Variable (PV) snapshot application; the third scenario evaluates the reliability improvement of a notification application by simulation; and the fourth scenario evaluates the modifiability improvement of the XRD application in order to fulfil emerging requirements. The results show that the RSC approach outperforms the orchestration approach in every aspect.

In addition to storing 70-75% of their data and business logic in legacy mainframe systems, global corporations have countless custom applications and off-the-shelf ERP products residing within their networks. Increasing competition and shrinking budgets have left managers scouring for innovative, cost-effective methods to maximize the potential of these enormous sunk costs. There is, as a result, an overwhelming need to not only web enable these existing legacy assets in order to quickly and cost-effectively deliver data to both customers and business partners alike, but also to amalgamate these disparate systems into a unified, homogeneous, real-time enterprise. Integration efforts to date, focused predominantly on the development of proprietary point-to-point adapters, have unfortunately proven to be a daunting task with countless failed projects and losses in the millions. The advent of XML web services does, however, have the potential to revolutionize existing integration strategies; the cost savings and ease of implementation associated with wrapping virtually all systems, past, present and future, with standardized, code-independent, data-centric interfaces is truly astounding. As the future success of this platform is, however, strictly dependent upon the interoperability of its endpoints, we have proposed several fundamental amendments to the existing flawed WSDL specification. A generic reference architecture, leveraging both this improved web services model as well as established component middleware technologies, is then proposed for the web enablement of legacy assets on an enterprise scale. In order to ensure the adoption of this methodology, a toolkit designed to automate the transformation has also been devised. This new paradigm will not only allow information to flow freely from deep within the enterprise, but will ultimately serve as the cornerstone of a new generation of enterprise integration solutions.

This thesis presents a framework for semantic Web Service discovery using descriptive (non-functional) service characteristics in a large-scale, multi-domain setting. The framework uses Web Ontology Language for Services (OWL-S) to design a template for describing non-functional service parameters in a way that facilitates service discovery, and presents a layered scheme for organizing ontologies used in service description. This service description scheme serves as a core for desigining the four main functions of a service directory: a template-based user interface, semantic query expansion algorithms, a two-level indexing scheme that combines Bloom filters with a Distributed Hash Table, and a distributed approach for storing service description. The service directory is, in turn, implemented as an extension of the Open Service Discovery Architecture. <br /><br /> The search algorithms presented in this thesis are designed to maximize precision and completeness of service discovery, while the distributed design of the directory allows individual administrative domains to retain a high degree of independence and maintain access control to information about their services.

No description available.

Today, advancements in the information technologies increased the significance of electronic business in the world. Besides the numerous advantages provided by these advancements, competition has also increased for the enterprises. In this competitive environment, companies have to access information faster and response to the changes quickly. In a supply chain, it is a highly possible that one of the partners may defect in providing its services. When these exceptional cases occur, the pending parties have to establish transitory collaborations to replace the missing partner promptly in order not to suffer this deficiency economically. Companies need to know the competences and capabilities of their prospective business partners before establishing partnerships. Furthermore, the reputations of the candidate partners have to be known to avoid possible regrettable partnerships. In this thesis, we have developed a trust and reputation model that can be used over supply chains to determine and exploit the reputation of providers in transitory collaboration formation. The trust model takes the behaviors of providers, consumers into account and combines multiple criteria to aggregate a single reputation value. Experimental results show that, our model provides a robust and reliable reputation mechanism addressing a number of issues that have not been covered in the related studies. In addition to this, an implementation of the model is realized within a Web application and the functionalities have been exposed as Web Services. The interoperability of the Web Services have been ensured through standard GS1 XML documents, which are utilized and extended in scope of the thesis. Furthermore, client interaction is provided through Web based user interfaces and REST services.

One of the most crucial decisions when developing a system based on Service Oriented Architecture is to select an appropriate server which will be the ground for building the application. Similar to databases, an application server has significant influence on efficiency, stability, and security of entire system. During the preparation of architecture for system development one has to decide which available application server would be optimal for hosting and maintaining v Web Services in the given case. There are multiple significant criteria that lead to the proper choice. The impact on a decision among other things is type of the physical machine on which the application server is installed, estimated number of simultaneous clients, and sizes of requests and responses between clients and server. The goal for this thesis is to conduct the comparative analysis of the most commonly used application servers using Service Oriented Architecture and to determine which server should be applied in which particular cases. Performance and load tests will be conducted using SoapUI application.

With increasing number of applications in Internet and mobile environments, distributed software systems are demanded to be more powerful and flexible, especially in terms of dynamism and security. This dissertation describes my work concerning three aspects: dynamic reconfiguration of component software, security control on middleware applications, and web services dynamic composition. <br><br> Firstly, I proposed a technology named Routing Based Workflow (RBW) to model the execution and management of collaborative components and realize temporary binding for component instances. The temporary binding means component instances are temporarily loaded into a created execution environment to execute their functions, and then are released to their repository after executions. The temporary binding allows to create an idle execution environment for all collaborative components, on which the change operations can be immediately carried out. The changes on execution environment will result in a new collaboration of all involved components, and also greatly simplifies the classical issues arising from dynamic changes, such as consistency preserving etc. <br><br> To demonstrate the feasibility of RBW, I created a dynamic secure middleware system - the Smart Data Server Version 3.0 (SDS3). In SDS3, an open source implementation of CORBA is adopted and modified as the communication infrastructure, and three secure components managed by RBW, are created to enhance the security on the access of deployed applications. SDS3 offers multi-level security control on its applications from strategy control to application-specific detail control. For the management by RBW, the strategy control of SDS3 applications could be dynamically changed by reorganizing the collaboration of the three secure components. <br><br> In addition, I created the Dynamic Services Composer (DSC) based on Apache open source projects, Apache Axis and WSIF. In DSC, RBW is employed to model the interaction and collaboration of web services and to enable the dynamic changes on the flow structure of web services. <br><br> Finally, overall performance tests were made to evaluate the efficiency of the developed RBW and SDS3. The results demonstrated that temporary binding of component instances makes slight impacts on the execution efficiency of components, and the blackout time arising from dynamic changes can be extremely reduced in any applications. / Heutige Softwareanwendungen fuer das Internet und den mobilen Einsatz erfordern bezueglich Funktionalitaet und Sicherheit immer leistungsstaerkere verteilte Softwaresysteme. Diese Dissertation befasst sich mit der dynamischen Rekonfiguration von Komponentensoftware, Sicherheitskontrolle von Middlewareanwendungen und der dynamischen Komposition von Web Services. <br><br> Zuerst wird eine Routing Based Workflow (RBW) Technologie vorgestellt, welche die Ausfuehrung und das Management von kollaborierenden Komponenten modelliert, sowie fuer die Realisierung einer temporaeren Anbindung von Komponenteninstanzen zustaendig ist. D.h., Komponenteninstanzen werden zur Ausfuehrung ihrer Funktionalitaet temporaer in eine geschaffene Ausfuehrungsumgebung geladen und nach Beendigung wieder freigegeben. Die temporaere Anbindung erlaubt das Erstellen einer Ausfuehrungsumgebung, in der Rekonfigurationen unmittelbar vollzogen werden koennen. Aenderungen der Ausfuehrungsumgebung haben neue Kollaborations-Beziehungen der Komponenten zufolge und vereinfachen stark die Schwierigkeiten wie z.B. Konsistenzerhaltung, die mit dynamischen Aenderungen verbunden sind. <br><br> Um die Durchfuehrbarkeit von RBW zu demonstrieren, wurde ein dynamisches, sicheres Middleware System erstellt - der Smart Data Server, Version 3 (SDS3). Bei SDS3 kommt eine Open Source Softwareimplementierung von CORBA zum Einsatz, die modifiziert als Kommunikationsinfrasturkutur genutzt wird. Zudem wurden drei Sicherheitskomponenten erstellt, die von RBW verwaltet werden und die Sicherheit beim Zugriff auf die eingesetzten Anwendungen erhoehen. SDS3 bietet den Anwendungen Sicherheitskontrollfunktionen auf verschiedenen Ebenen, angefangen von einer Strategiekontrolle bis zu anwendungsspezifischen Kontrollfunktionen. Mittels RBW kann die Strategiekontrolle des SDS3 dynamisch durch Reorganisation von Kollabortions-Beziehungen zwischen den Sicherheitskomponenten angepasst werden. <br><br> Neben diesem System wurde der Dynamic Service Composer (DSC) implementiert, welcher auf den Apache Open Source Projekten Apache Axis und WSIF basiert. Im DSC wird RBW eingesetzt, um die Interaktion und Zusammenarbeit von Web Services zu modellieren sowie dynamische Aenderungen der Flussstruktur von Web Services zu ermoeglichen. <br><br> Nach der Implementierung wurden Performance-Tests bezueglich RBW und SDS3 durchgefuehrt. Die Ergebnisse der Tests zeigen, dass eine temporaere Anbindung von Komponenteninstanzen nur einen geringen Einfluss auf die Ausfuehrungseffizienz von Komponeten hat. Ausserdem bestaetigen die Testergebnisse, dass die mit der dynamischen Rekonfiguration verbundene Ausfallzeit extrem niedrig ist.

Since 1993 The US government took the lead to propose the ¡§National Information Infrastructure, (NII)¡¨ plan, many countries started to establish the electronic government to provide the populace with innovation services.. The services of electronic government have to evolve from ¡§Do Government Better¡¨ into ¡§Do Better Government¡¨. Now the network has evolved into a new generation that emphasizes on users co-constructing the cyber contents - Web 2.0. Could Web 2.0 be applied to the web services of the electronic government? How should the electronic government provide the innovation services by using Web 2.0? What are the Web 2.0 services provided by the local government in Taiwan? The above questions are the key points of this research. This research was based on the web service type of government and the mature application of Web 2.0 to establish 4 categories (Blog, Instant Messaging, Podcast and RSS) and 17 indicators to construct questionnaire, and review local government web services in Taiwan. This research used the census method to observe 25 local government website by the researcher during 2008/4/7~2008/4/9. Also the all 25 local government website administrators in Taiwan completed the questionnaire separately during 2008/4/21~2008/5/13. According to the research results, that Web 2.0 services on Taiwan local government were: (1) the primary service provided by local government is automatic information service, (2) the online multimedia playing service is getting mature gradually, (3) the web call is the main online intercommunication service, (4) the concepts of blog service has not established yet, (5)there are many problems to surmount for advancing Web 2.0 Services, such as the definitions of Web 2.0 Services, the doubts of information security etc.. Overall, Web 2.0 for local government online services is still at beginning stage in Taiwan. Besides this research provides the following suggestions about Web 2.0 innovations for government services online: (1) to establish the better understanding of Web 2.0 Services, (2) to develop guidelines of Web 2.0 services and evaluation criteria, (3) to provide financial motivation and technical support.

The recent development of the service-oriented architecture (SOA) has provided an opportunity to apply this new technology to support model management. This is particularly critical when more and more decision models are delivered as web services. A web-services-based approach to model management is useful in providing effective decision support. When a decision model is implemented as a web service, it is called a model-based web service. In model management, selecting a proper model-based web service is an important issue. Most current research on selecting such web service relies on matching inputs and outputs of the model, which is oversimplified. The incorporation of more semantic knowledge may be necessary to make the selection of model-based web services more effective. In this research, we propose a new mechanism that represents the semantics associated with a problem and then use the similarity of semantic information between a new problem description and existing web services to find the most suitable web services for solving the new problem. The paper defines the concept of entity similarity, attribute similarity, and functional similarity for problem matching. The web service that has the highest similarity is chosen as a base for constructing the new web services. The identified mapping is converted into BPEL4WS codes for utilizing the web services. To verify the feasibility of the proposed method, a prototype system has been implemented in JAVA.

<p>There is a great deal of interest burgeoning in the intellectual community regarding Web Services and their usage. Many writers have tried to bring awareness about some unconceived threats lurking behind the enticing Web Services. Threats due to Web Services are on an all time high giving an alarming knock to the Web Services security community. This led to the, Organization for the Advancement of Structured Information Standards (OASIS) made some constraints mandatory in order to standardize message security and these constraints and specifications are presented through a document called WS Security -2004. This work is an attempt to check the support offered by various Web Services Tools available currently. It introduces the reader to Web Services and presents an overview of how far some of the tools have reached in order to make the Web Services environment safe, secure and robust to meet the current day’s requirements. A quantitative approach was taken to investigate the support offered by servers like BEA, Apache Axis etc. The conclusions drawn show that most of the tools meet the imposed standards but a lot more is expected from the web community and these tools; if at all the visions about safe and secure Web Services are to be realized.</p>