Measurement-based performance analysis of e-commerce applications with Web services components

Towards a context-based multi-type policy approach for Web services composition

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.

Service composition makes use of existing service-based applications as components to achieve a business goal. In time critical business environments, the response time of a service is crucial, which is also reflected as a clause in service level agreements (SLAs) between service providers and service users. To allow the composite service to fulfill the response time requirement as promised, it is important to find a feasible set of component services, such that their response time could collectively allow the satisfaction of the response time of the composite service. In this work, we propose a fully automated approach to synthesize the response time requirement of component services, in the form of a constraint on the local response times, that guarantees the global response time requirement. Our approach is based on parameter synthesis techniques for real-time systems. It has been implemented and evaluated with real-world case studies.

Web service adaptation is an important feature for mission critical Web services. It is widely recognized that thrashing and crashes occur in system saturation for many statically adaptive resource management algorithms, including CPU, memory, and network congestion. Service adaptation supports alternative responses to saturation control, maintaining service and server system stability and progress, instead of thrashing. In this paper, we present a design framework for developing adaptive web services. The core of this framework is the adaptation space model, which is based on the concepts of adaptation space and adaptation case. An adaptation space is defined by a use context and a partial order of adaptation cases. Each adaptation case describes a specific adaptation of a program or component of a web service. There are three main thrusts of the adaptation space approach. First, it defines a multi-dimensional adaptation context for capturing and coordinating different kinds of adaptation at different levels of a web service. Second, it provides a uniform way for representing and viewing a collection of alternative adaptations for a given web service component. Third, it promotes a declarative and incremental approach to adaptation specification, allowing the incorporation of new adaptation behavior of a web service in terms of existing adaptation cases. We evaluate the adaptation space approach using Ginga, an adaptive query processing service for handling queries over multiple data sources with diverse capabilities across the Internet. Our experimental results show that Ginga query adaptation can achieve significant performance improvements (up to 40% of response time gain) for processing distributed queries over the Internet in the presence of end-to-end delays.

A service oriented application consists of component web services which cooperate with each other to offer the desired functionality. Due to the distributed and unpredictable nature of the underlying environment, the component web services have uncertain dependability characteristics. This paper looks into the issue of web service availability. The paper proposes a proactive framework to manage the situation when third party web services become unavailable. Software agents are employed to monitor web services on the provider side. The framework is implemented in J2EE, using JADE environment for creating and deploying software agents. Experimental analysis shows that the proposed solution is effective and behaves considerably well when availability of component web services is varied from 0 % to 100 %.

As the amount of pathway information for various organisms is increasing very rapidly, performing various analyses on the full network of pathways for even multiple organisms can be possible and therefore developing an integrated database for storing and analyzing pathway information is becoming a critical issue. Until now analyzing these networks is not easy because of the nature of the existing pathway databases, which are often heterogeneous, incomplete, and/or inconsistent. We presented a database system called SPDBS to solve this problem. However, application-oriented systems like SPDBS have some limitations on the extension and integration of the heterogeneous databases. In this paper, we extend previous SPDBS into a web service prototype (SPDBSW) where all functions can be serviced on the web environment. The web services include pathway database integration/search, import/export of SBML documents, pathway reconstruction/visualization. SPDBSW has been implemented by the combination SPDBS and external web services such as OLS, KEGG and NCBI. And user can get more confidential and delicate information from KEGG or NCBI through their web services. The system can be extended or modified immediately by replacing its component web services. We provide SPDBSW at the website http://database.chungbuk.ac.kr/SPDBSW.

The 90 Day Challenge team set out to deliver an end-to-end Web services solution to enterprise sales agents in 90 days, with immediate plans to extend the solution to other user groups. In order to meet their commitments, the team had to reuse the same component Web services in multiple contexts. By modeling the workflows and carefully managing scope at the component level, the team developed a suite of Web services that other teams could easily incorporated into multiple projects. As a result, twelve other programs to date have incorporated Web services from the 90 Day Challenge, saving weeks of development time.

Reputation is useful for establishing trust between Web service (WS) providers and WS consumers. In the context of WS composition, a challenging issue of reputation management is to propagate a user's impression of a composite WS (i.e., the user's feedback rating) to its component WSs. In this paper, we propose a Shapley value based approach which can achieve fair impression propagation, that is, the reputation of a component WS is never awarded (or penalized) for the good (or bad) performances of the other peer component WSs in the same composite WS. The fairness of the proposed approach is validated through theoretical analysis and experimental results.

This study introduces a distributed e-learning system on power line network. E-learning system, in general, consists of learning management system (LMS) for managing users and courses, learning content management system (LCMS) for offering educational contents to learners and course authoring for course and content design. Today, there is a great deal of requests, issued simultaneously by worldwide users from any place at any time, for e-learning systems. Because of enormous amount of requests and simultaneous connections of users, server's performance and response time may degrade. Power line communication has high influence and is high speed medium that can be utilized as platform for e-learning. On the other hand, it is possible to implement distributed e-learning system on a power line network to distribute load of requests on multiple servers and improve their performances. In this paper, we propose software architecture and network design for distributed e-learning system on power line network.

Internet and Mobile technologies have greatly changed our lives in the past decade. However, the power and patentlals of the cambined capabilities offered by these two major inventions remain untapped. This paper looks into how we can turn these capabilities into service components that can be assembled into various composite services and enable people to have a simple way to enjoy camprehensive services anytime, anywhere, anyway with user and context relevance. We will explain in this paper how Web Services technologies and Service Oriented Architecture enables rapidly service creation; and the power of combining web technologies and mobile capabilities for service execution. Tourism is ane vertical industry chosen to apply this Service Provisioning concept. A packaged tour prototype is built to demonstrate the creation and execution of various tour services. These packaged tour services inciude both web and mobile service components and are described in service logic. Utilising the published services co...

This paper describes a generalized web-based framework for VBI pathosystems informatics & bioinformatics web services. The framework provides a universal mechanism for accessing web services through web browsers. A web service can be configured to the framework easily. The framework is designed using object-oriented methodology and implemented using Java 2 Enterprise Edition, relational databases, XML technology and various other open source technologies. It is designed to conform to a n-tiered architecture that includes several layers: a web-based graphical user interface built using Apache Struts web framework running on Apache Jakarta Tomcat; a business object layer, server and web service components that process the queries and manipulate the result sets; and a robust data access layer. The system provides an extensible, flexible, and user-friendly framework for any generic bioinformatics projects, including genome curation, micro-array gene expression profiles, pathogen information curation and pathway analysis, etc.

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.

Today, in the field of computer networks, new services have been developed on the Internet or intranets, including the mail server, database management, sounds, videos and the web server itself Apache. The number of solutions for this server is therefore growing continuously, these services are becoming more and more complex and expensive, without being able to fulfill the needs of the users. The absence of benchmarks for websites with dynamic content is the major obstacle to research in this area. These users place high demands on the speed of access to information on the Internet. This is why the performance of the web server is critically important. Several factors influence performance, such as server execution speed, network saturation on the internet or intranet, increased response time, and throughputs. By measuring these factors, we propose a performance evaluation strategy for servers that allows us to determine the actual performance of different servers in terms of user satisfaction. Furthermore, we identified performance characteristics such as throughput, resource utilization, and response time of a system through measurement and modeling by simulation. Finally, we present a simple queue model of an Apache web server, which reasonably represents the behavior of a saturated web server using the Simulink model in Matlab (Matrix Laboratory) and also incorporates sporadic incoming traffic. We obtain server performance metrics such as average response time and throughput through simulations. Compared to other models, our model is conceptually straightforward. The model has been validated through measurements and simulations during the tests that we conducted.

We present a way to automatically compose Web service workflow that uses component Web services. The Web services workflows are described using our transactional workflow ontology. The workflow ontology can be used to describe both component Web service workflows and master Web service workflows. We have also implemented a workflow engine that runs the workflow instances. Here we analyze using our ontology and some workflow instances with a reasoning agent to automatically find a composed workflow that fulfills all given constraints. The result from the inference is a workflow instance that can be executed using our workflow engine. We see that this kind of dynamic composition is needed in dynamic heterogeneous environments with loosely coupled Web services.

Web service (WS) providers need to restrain access to private information when cooperating with business partners. This need is translated in practice by an abstraction phase where inner data is withheld from public view. However, just like hiding encryption keys is not enough to prove the secrecy of information in a communication protocol, this procedure cannot prove the goal of secrecy is attained. Security related literature has turned in the past couple of decades to a new, formal, security property, i.e., opacity, to both hide and prove the privacy of secrets. Following our previous work on the use of the Symbolic Observation Graph (SOG), on one hand, to abstract and compose Web services, and to verify the opacity of systems on the other, we show in this paper how the verification of three different types of opacity in SOG-abstracted WSs is translated to the opacity of their composites. We hence establish that the SOG is a suitable abstraction that allows to check these opacity variants locally to each component of a composite WS, and preserves opacity by composition (i.e., each WS component is opaque iff the composite WS is).