The Role of Web Services

This chapter aims to examine the extent of Web services usage and quality, applying the balanced scorecard methodology in a small business firm as an exploratory case study. This chapter contributes to guidelines and lessons learned that will inform, educate, and promote small businesses on the importance of maintaining the quality of Web services.

Providing Web Services Security SLA Guarantees

This chapter underlines the importance of security service level agreements (SLAs) for Web services. As Web services are increasingly incorporated in the mainstream enterprises, the need for security has led to various standards. However unlike nonfunctional requirements such as performance, scalability and so forth, which are quantitative and are enforced through SLAs, security is represented only through policies. There exist quite a few frameworks for security at different levels of enactment; however, what is clearly missing is an approach to represent security SLAs and enacting them for a Web service environment. In this chapter, we primarily focus on two aspects. We first focus on the security requirements for Web services and the currently available stack of security mechanisms and frameworks for achieving security at various levels of Web service implementation. The second focus is on how these could be utilized to build security SLAs, which could be enforced on Web services. Later in the chapter we suggest a conceptual model to represent these SLA clauses and present an approach to enact them.

Service Evolution and Maintainability

Change is the only constant, and this concept holds good for services too. Service maintenance is the most tedious and longest phase of service lifecycle. The more complex the service, the more difficult it is to maintain it. Service maintenance and service evolution mandate a series of best practices and selective models to apply for better execution and administration. In this chapter we detail the challenges faced in service evolution management and the key activities involved, and their role in service-oriented architecture (SOA) quality.

Adoption of Web Services in Digital Libraries

This chapter describes a research study with an objective to explore and describe decision factors related to technology adoption. The study utilized theories of diffusion of innovations and communities of practice as frameworks and a case study of Web services (WS) technology in the digital library (DL) environment to develop an understanding of the decision-making process. A qualitative case study approach was used to investigate the research problems and data was collected through semistructured interviews, documentary evidence (e.g., meeting minutes), and a comprehensive member check. Face-to-face and phone interviews were conducted with respondents from five different DL programs in the U.S., selected based on distinctive characteristics (e.g., size of the DL program). Findings of the research suggest that the decision-making process is a complex procedure in which a number of factors are considered when making WS adoption decisions. These factors are categorized as organizational, individual, and technology-specific factors.

Open Security Framework for Unleashing Semantic Web Services

The lack of intrinsic and user control in the identity management of today Internet security hampers the research in the area of Semantic Web and service-oriented architectures. Semantic Web research is seeking to develop expert Web services that are a composition of specialized Web services of multiorganizations. To unleash these emergent Web services, we propose an open security framework that is based on the concept of personal identity management. Despite the resistance from today’s Internet security dominated by domain-centric identity management, we believe that when all the alternatives are exhausted, the industry will come to the conclusion that the concept of personal identity management is the only approach to provide true user-centric identity management and give users control over the management of their identities.

Aspect-Oriented Framework for Web Services (AoF4WS)

This chapter presents our research initiative known as aspect-oriented framework for Web services (AoF4WS). This initiative looks into the role of aspect-oriented programming in enhancing Web services with nonfunctional properties that are orthogonal to the primary functional properties of Web services, without the need for extensive reprogramming. This enhancement achieves a separation between the functional and nonfunctional aspects of Web services, thereby resulting in easier adaptability and maintainability. We have initially chosen to focus on security and self-healing nonfunctional requirements. The AoF4WS initiative is therefore demonstrated using two projects, SC-WS and SH-WS, which respectively stand for security concerns of Web services and self-healing Web services. Our contributions are relevant to the design phase in an aspect-oriented software development lifecycle.

Enhancing the Testability of Web Services

For the foreseeable future, testing will remain the mainstay of software quality assurance and measurement in all areas of software development, including Web services and service-oriented systems. In general, however, testing Web services is much more challenging than testing normal software applications, not because they are inherently more complex, but because of the limited control and access that users of Web services have over their development and deployment. Whereas the developers of normal applications, by definition, have full control over their application until release time, and thus, can subject them to all kinds of tests in various combinations (e.g., integration testing, system testing, regression testing, acceptance testing, etc.), users of Web services can often only test them at run-time after they have already been deployed and put into service. Moreover, users of Web services often have to share access to them with other concurrent users. In order to effectively test Web services under these conditions special measures and approaches need to be taken to enhance their testability. Right from the early phases of development, the testability of services needs to be taken into account and “designed into” services. In this chapter we consider these issues and with the aid of a case study we present a methodology that can be used to enhance the testability of Web services.

Web Services Dependability

This chapter presents the definition of relevant terminology and a conceptual model of the basic terms. The chapter starts with the presentation of research in the area of dependability. Based on this, Web service concepts related to the dependability are introduced. The presentation leads into a statement identifying individual quality-of-service (QoS) characteristics for forming dependable Web services. Then, the chapter discusses the current status quo in the area of QoS-aware Web services. This part is divided into three subparts: description, management, and monitoring. This also identifies ongoing efforts as well as efforts that do not show present activity. By this discussion, this chapter puts research about dependability in relation with ongoing QoS-related efforts in the Web services domain. Thus it identifies how these efforts can be combined in order to form a dependable Web services platform.

Quality Models for Multimedia Delivery in a Services Oriented Architecture

In this chapter we present an overview of research and development efforts across several different technical communities aimed at enabling efficient and standardized end-to-end delivery of multimedia content over a service-oriented architecture (SOA). We focus primarily on issues related to quality of service (QoS) specification, measurement, and enforcement for different multimedia distribution applications in this space.

Profiling of Web Services to Measure and Verify their Non-Functional Properties

The following chapter focuses on the problem of the proper definition of non-functional properties and methods that may be applied in order to estimate their values. First of all, a reader is familiarized with the concept of non-functional properties and different views on the quality of Web services. Then, selected approaches to obtain values of non-functional properties are presented. The focus of attention is Web services profiling that seems to be one of the most promising methods to perform this task. The framework presented in this chapter was implemented and tested within the EU Adaptive Services Grid project.