Agent-based computing is an emerging computing paradigm that has proved extremely successful in dealing with a number of problems arising from new technological developments and applications. In this paper we report the role of computational logic in modeling intelligent agents, by analysing existing agent theories, agent-oriented programming languages and applications, as well as identifying challenges and promising directions for future research. 1 Introduction In the past ten years the eld of agent-based computing has emerged and greatly expanded, due to new technological developments such as ever faster and cheaper computers, fast and reliable interconnections between them as well as the emergence of the world wide web. These developments have at the same time opened new application areas, such as electronic commerce, and posed new problems, such as that of integrating great quantities of information and building complex software, embedding legacy code. The establishment o...

We discuss from a practical point of view a number of issues involved in writing distributed Internet and WWW applications using LP/CLP systems. We describe PiLLoW, a publicdomain Internet and WWW programming library for LP/CLP systems that we have designed in order to simplify the process of writing such applications. PiLLoW provides facilities for accessing documents and code on the WWW; parsing, manipulating and generating HTML and XML structured documents and data; producing HTML forms; writing form handlers and CGI-scripts; and processing HTML/XML templates. An important contribution of PiLLoW is to model HTML/XML code (and, thus, the content of WWW pages) as terms. The PiLLoW library has been developed in the context of the Ciao Prolog system, but it has been adapted to a number of popular LP/CLP systems, supporting most of its functionality. We also describe the use of concurrency and a highlevel model of client-server interaction, Ciao Prolog’s active modules, in the context of WWW programming. We propose a solution for client-side downloading and execution of Prolog code, using generic browsers. Finally, we also provide an overview of related work on the topic.

. We dene HTML as an embedded domain specic language in Haskell. To this end, we have designed and implemented a combinator library which provides the means to create and modify HTML elements. Haskell's type classes are employed to enforce well-formed HTML to a large degree. Haskell can then be used as a meta language to map structured documents to HTML, to dene conditional content, to extract information from the documents, or to dene entire web sites. We introduce container-passing style as a programming convention for the library. We also pinpoint some shortcomings of Haskell's type system that make the task of this library's implementor tedious. Key words: embedded domain specic language, HTML, functional programming, type classes 1 Introduction Programming one web page in isolation is not hard. Programming an entire web site can be a nightmare. While simple HTML editors help with the rst task [23, 9], full blown web authoring systems are required for the other ta...

Abstract. Prototyping is a valuable technique to help software engineers explore the design space while gaining insight on the dynamics of the system. In this paper, we describe a method for rapidly building prototypes of large multi-agent systems using logic programming. Our method advocates the use of a description of all permitted interactions among the components of the system, that is, the protocol, as the starting specification. The protocol is represented in a way that allows us to automatically check for desirable properties of the system to be built. We then employ the same specification to synthesise agents that will correctly follow the protocol. These synthesised agents are simple logic programs that engineers can further customise into more sophisticated software. Our choice of agents as logic programs allows us to provide semi-automatic support for the customisation activity. In our method, a prototype is a protocol with a set of synthesised and customised agents. Executing the prototype amounts to having these agents enact the protocol. We have implemented and described a distributed platform to simulate prototypes. 1.

. As use of Web sites has exploded, large amount of eort have gone into the deployment of sites but little thought has been given to methods for their design and maintenance. This paper reports some encouraging results on the use of automated synthesis, using domain-specic formal representations, to make design more methodical and maintenance less time consuming. Key Words: Web site application, computational logic, HTML. 1 Introduction Web site maintenance has become a challenging problem due to the increase in size and complexity of Web site applications. It often involves access to databases, complex cross referencing between information of the site and sophisticated user interaction. Web sites applications related to a same domain often share a common pattern. Consider, for example, the Software Systems and Processes Group at Edinburgh (www.dai.ed.ac.uk/ groups/ssp/index.html) the research group Web sites of the Articial Intelligence Research Institute in Barcelona (www.iiia...

A number of data description languages initially designed as standards for the WWW are currently being used to implement user interfaces to programs. This is done independently of whether such programs are executed in the same or a different host as the one running the user interface itself. The advantage of this approach is that it provides a portable, standardized, and easy to use solution for the application programmer, and a familiar behavior for the user, typically well versed in the use of WWW browsers. Among the proposed standard description languages, VRML is a aimed at representing three dimensional scenes including hyperlink capabilities. VRML is already used as an import/export format in many 3-D packages and tools, and has been shown effective in displaying complex objects and scenarios. We propose and describe a Prolog library which allows parsing and checking VRML code, transforming it, and writing it out as VRML again. The library converts such code to an internal repres...

This papers shows the deployment of the processing and computational facilities of Prolog to query on XML documents and to reason about their content. Based on a case study we show that it is feasible and useful to deploy Prolog in complex, mobile agent environments. We introduce a rule-based system component which reasons about XML documents and their content respectively. It provides a state-of-the-art World Wide Web interface to connect to multi agent applications.