Vol.1 No.2 March, 2003

In This Issue (pp91-92)
          M. Gaedke
Research Articles and Reviews:
Enhancing Hyperlink Structure for Improving Web Performance (pp93-127)
      J. Czyzowicz, E. Kranakis, D. Krizanc, A. Pelc, and M.V. Martin
In a Web site, each page $v$ has a certain probability $p_{v}$ of being requested by a user. The access cost of a Web site is the sum of $p_{v}\cdot c(r,v)$, of every page $v$, where $c(r,v)$ is the cost of the shortest path between the home page, $r$, and page $v$. The cost of a path is measured in two ways. One measure is in terms of its length, where the cost of the path is simply the number of hyperlinks in it. The other measure is in terms of the data transfer generated for traversing the path. This research work concerns the problem of minimizing the access cost of a Web site by adding hotlinks over its underlying structure. We propose an improvement on Web site access by making the most popular pages more accessible to users. We do this by assigning hotlinks to the existing structure of the Web site. The problem of finding an optimal assignment of hotlinks is known as the hotlink assignment problem. We present heuristic algorithms which are tested and compared by simulation on real and random Web sites. We develop The Hotlink Optimizer (HotOpt), a new software tool that finds an assignment of hotlinks reducing the access cost of a Web site. HotOpt is empowered by one of the algorithms presented in this paper.

An Enhanced Service Oriented Architecture for Developing Web-based Applications (pp128-146)
      D. Cotroneo, C. di FLora and S. Russo
Web services architectures have recently emerged as a standard, service oriented approach for developing Internet-scale distributed systems. Such architectures are characterized by discovery and delivery infrastructures, since service provisioning follows the publish-find-bind paradigm. Recently, a variety of service oriented architectures have been proposed, where service discovery infrastructure does not take into account non-functional requirements associated to a service. Furthermore, service repositories are merely conceived as service descriptors containers, without any relationship with the actual availability of services. This paper proposes an enhanced service oriented architecture, called PRINCEPS, particularly suited for developing web-based applications. PRINCEPS resorts to a novel service discovery protocol which assembles services at run-time according to both functional and non-functional client requirements. The protocol is XML-based and it exploits a lease mechanism to maintain service repositories consistent with actual running service instances. PRINCEPS is endued with a service delivery infrastructure, which is based on the HTTP protocol, and allows extended client-server models to be implemented. PRINCEPS is interoperable with web-service technologies standardized by the world wide web consortium. A complete example, which shows the advantages of PRINCEPS architecture, is also provided.

 An XML-Based Platform for E-Government Services Deployment (pp147-162)
      A. Ioannidis, M. Spanoudakis, G. Priggouris, S. Hadjiefthymiades, and L. Merakos
Transaction services that enable the on-line acquisition of information, the submission of forms and tele-voting, are currently viewed as the future of E-Government. Deploying such services requires platform independent access and communications security as a basis. This paper presents a platform for supporting E-Government services in a highly distributed public network environment, based on XML protocols. We discuss the technical details of the developed software that implements these XML protocols. The platform relies on the well-established IPsec and SSL/TLS technologies for ensuring the security of the critical, e-government related data, exchanged over the public network.

Specification and Design of Workflow-Driven Hypertexts (pp163-182)
      M. Brambilla, S. Ceri, S. Comai, P. Fraternali and I. Manolescu
While the Web consolidates as the ubiquitous application delivery platform, the features of Web applications evolve to cover new requirements, like the capability of managing complex workflows spanning multiple users and organizations. This scenario challenges the Web engineering methods to address a broader class of applications. This paper introduces workflow-driven hypertexts, defined as Web-enabled hypertextual applications serving the workflow of multiple users, and proposes a design method integrating data, hypertext, and workflow modeling concepts for modeling lightweight Web-enabled workflows; this approach extends the benefits of high-level conceptual modeling and automatic code generation to a much broader class of Web applications.

Book Reviews:
On "Web Engineering: Managing Diversity nd Complexity of Web Application Development" ed by S. Murugesan and Y. Deshpande (pp183-184)
      B. White
Forthcoming Conferences on Web Engineering (pp185-186)

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