Many of the Web applications around us are data-intensive; this term indicates applications whose main purpose is presenting large amount of data to their users. Most of the sites for on-line trading or e-commerce are data-intensive, as well as most “institutional ” sites (describing private and public organizations) or digital libraries. Several commercial Web development systems enable the rapid development of data-intensive

In this paper we present an architecture for building families of rich Web applications. We first characterize current trends in Web applications, from read-only Web sites to sophisticated applications where complex distributed transactions must be supported. We next some design principles for building Web applications, and give the rationale for separating application behavior from navigation and interface issues. We briefly argue the need for developing a product line architecture for simplifying the systematic construction of different families of applications. We next describe the main components of our architecture explaining how we manage to decouple application specific aspects from technological aspects (such as dynamic page generation and persistence) that can be eventually solved by reusing of-the-shelf components. We show how to build application frameworks using this architecture using a concrete example of an electronic CD store.

Abstract. This paper presents StateWebCharts (SWC), a formal description technique based on statecharts for describing navigation on web applications. This notation extends the classical statecharts notation by adding more necessary concepts such as an appropriate semantics for states and transitions in a Web context, including notions like dialog initiative control and client and server activities. As well as statecharts do, this formal description technique features a graphical representation thus making it easier to use for web designers and formal enough to allow to rigorously reason about properties of navigation models. In order to show the applicability of the notation, we show, in the paper, its use on two real-size web applications. 1.

Web-based sales assistance systems are a valuable means to guide online customers in the decision-making and product selection process. Conversational recommenders simulate the behavior of an experienced sales expert, which is a knowledge-intensive task and requires personalized user interaction according to the customers' needs and skills. In this paper, we present the AD- VISOR SUITE framework for rapid development of conversational recommenders for arbitrary domains. In the system, both the recommendation logic and the knowledge required for constructing the personalized dialog and adaptive web pages is contained in a declarative knowledge-base. The advisory application can be completely modeled using graphical tools based on a conceptual model of online sales dialogs. A template mechanism supports the automatic construction of maintainable dynamic web pages. At run-time, a controller component generically steers the interaction flow. Practical experiences from several commercial installations of the system show that development times and costs for online sales advisory systems can be significantly reduced when following the described knowledge-based approach.

Abstract Most existing Web applications conceptual modeling approaches are based on a design concept, the page, on which the navigational specification of the system is usually built. However, their increasing personalization and mobility demands, together with the high pace at which new devices and technologies are appearing, are causing such applications and their related models to become increasingly complex and less reusable. This problem would be lessened by integrating a navigation analysis model exclusively based on the different user requirements. Supporting this idea, in this article we introduce two constructs that increase the level of abstraction at which navigational aspects are captured, namely the Navigation Semantic Unit (NSU) and the Navigation Semantic Link (NSL), and which are in the core of a navigational model independent from users, platforms and access devices. Also, we outline how this model can be integrated in a range of user-oriented hypermedia modeling approaches, and influence the way their navigation design models are constructed.

WebML is a high-level language for specifying the content structure of data-intensive Web applications, and the organization and presentation of such content through a hypertext structure. This paper concentrates on the conceptual design of structural schemas and hypertexts, which represents the core aspect of the WebML design process. In particular, the paper introduces a set of WebML skeletons, i.e., abstract and simplified versions of structural and hypertext schemas that are recurrent within Web applications. Then, it shows how skeletons can be composed to obtain several WebML application frameworks, which provide a classification of Web sites from the viewpoint of their predominant information-delivery mission (or business model). WebML skeletons and frameworks can be assumed as the initial start-point of design sessions, as well as paradigms for better understanding and classifying data-intensive Web applications.

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This paper presents a case study highlighting the best practices for designing and building a web-based auction system using UML (Unified Model Language) and component-based programming. We use the Use Case, Class, Sequence, and Component Diagrams offered by UML for designing the system. This enables new functions to be added and updated easily. Our implementation, with its basis in component-based programming, enabled us to develop a highly maintainable system with a number of reusable components: the MethodofBidding (the bidder can bid at three different frequencies- fast, medium or leisurely), the Certification (Identity verification function), and the RegistrationGood (Product entry function) Components. Further, the system uses intelligent agents that permit fair help to bidders participating in auctions and at the same time achieve maximum profit for the seller. The design and implementation environment, along with the tools used, provide excellent support for the successful development of the system. 1.

A sales advisory system is a tool supporting customers in the decision -making and buying process by interactive and personalized requirements elicitation and the provision of comprehensible product proposals and explanations. The particular challenges when building such systems lie in the strong interdependencies between the recommendation and personalization logic and the corresponding adaptive, web-based user interface. The ADVISOR SUITE tool described in this paper is a system that follows a consistent knowledge-based approach for all tasks that are required to build such intelligent sales advisory systems for arbitrary domains. The development of advisory applications is based on a conceptual model of online sales dialogues, a "Model-ViewController " application architecture, a generic controller component, as well as (semi-)automatic, template-based web page generation. Experiences from various real-world applications show that the knowledge-based approach and the corresponding graphical tools of ADVISOR SUITE significantly accelerate the development and maintenance process for such applications.