Vol.3 No.2 October, 2004
Editorial & In This Issue (pp075-076)
        M. Gaedke       
Research Articles and Reviews:
e-Prototyping: Iterative Analysis of Web User Requirements  (pp077-0094)
        W-G Bleek, M. Jeenicke and R. Klischewski
Projects developing Web applications face problems when it comes to identifying the Web users' requirements. There are a number of reasons for this. It is unclear how to gather initial requirements from potential users if there is no design artifact to communicate about. Developers have difficulty identifying the needs of the Web
application users during the ongoing development process because of a lack of proper communication concepts. Development teams for Web-based systems include professionals from different disciplines with diverse cultures. Members of the development team often belong to many different organizations with varying stakes in the project. This article presents a modified prototyping approach called \eprot. This approach includes frequent releases of software versions (based on short development cycles) as well as integrated mechanisms for gathering feedback from users and other relevant actors via the live system. It underlines the need to offer various communication channels to the users and to systematically order the different streams of feedback to enable the developers to identify the user requirements. \eprot encompasses the management of an agile software development process and the systematic evaluation of manifold feedback contributions.

Quantification of Authentication Mechanisms: a Usability Perspective (pp095-123)
        K. Renaud
Users wishing to use secure computer systems or web sites are required to authenticate themselves. Users are usually required to supply a user identification and to authenticate themselves to prove that they are indeed the person they claim to be. The authenticator of choice in the web environment is the simple password. Since the advent of the web the proliferation of secure systems has placed an unacceptable burden on users to recall increasing numbers of passwords that are often infrequently used. This paper will review the research into different types of authentication mechanisms, including simple passwords, and propose a mechanism for quantifying the quality of different authentication mechanisms to support an informed choice for web site administrators.

Model-Driven Web Usage Analysis for the Evaluation of Web Application Quality (pp124-152)
        P. Fraternali, P.L. Lanzi, M. Matera and A. Maurino
So far, conceptual modeling of Web applications has been used primarily in the upper part of the life cycle, as a driver for system analysis. Little attention has been put on exploiting the conceptual specifications developed during analysis for application evaluation, maintenance and evolution. This paper illustrates an approach for integrating the use of conceptual models in the lower part of the application life cycle. The approach is based on the adoption of {\em conceptual logs}, which are Web usage logs enriched with meta-data deriving from the application conceptual specifications. In particular, the paper illustrates how conceptual logs are generated and exploited in Web usage evaluation and mining, so as to achieve a deeper and systematic quality evaluation of Web applications. A prototype tool supporting the generation of conceptual logs and the evaluation activities is also presented.

On the Image content of a Web Segment: Chile as a Case Study (pp153-168)
        A. Jaimes  J. Ruiz-del-Solar, R. Verschae, R. Baeza-Yates, C. Castillo, D. Yaksic, and E. Davis
 We propose a methodology to characterize the image contents of a web segment, and we present an analysis of the contents of a segment of the Chilean web (.CL domain). Our framework uses an efficient web-crawling architecture, standard content-based analysis tools (to extract low-level features such as color, shape and texture), and novel skin and face detection algorithms. In an automated process we start by examining all websites within a domain (e.g., .cl websites), obtaining links to images, and downloading a large number of the images (in all of our experiments approx. 383,000 images that correspond to about 35 billion pixels). Once the images are downloaded to a local server, our process automatically extracts several low-level visual features (color, texture, shape, etc.). Using novel algorithms we perform skin and face detection. The results of visual feature extraction, skin, and face detection are then used to characterize the contents of a web segment. We tested our methodology on a segment of the Chilean web (.cl), by automatically downloading and processing 183,000 images in 2003 and 200,000 images in 2004. We present some statistics derived from this last set of 200,000 images, which should be of use to anyone concerned with the image content of the web in Chile. Our study is the first one to use content-based tools to determine the image contents of a given web segment.

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