Principles of Object-Oriented Software Development
[] readme course preface 1 2 3 4 5 6 7 8 9 10 11 12 appendix lectures resources

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Web applications

The explosive growth of the Web is perhaps the single most important event in the history of computing technology. What started as an information infrastructure is now turning into an infrastructure encompassing both information and applications, and is becoming the backbone for the commercial deployment of the Internet.


Web Applications

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Additional keywords and phrases: Web Objects, XML, Java, CORBA, multimedia, software architecture


slide: Web applications

In this chapter, we will explore how the Web affects (object-oriented) software development. First of all, we will discuss whether object orientation has any relevance for the Web and for the development of Web applications. We will look at some of the current trends and technologies, discuss the possible occurrence of the Object Web, and look at an example deploying Web technology to provide an infrastructure for distributed object computing. We will reflect on the computation model underlying the Web, to explore how to program the Web to suit our needs. We will also look at the phenomenon of intelligent agents on the Web, which may aid the user in retrieving the right information and perform his/her tasks in a more convenient way. We then present some of our early research on extending the Web with multimedia fuctionality, carried out in the DejaVU project at the Vrije Universiteit. Concluding this chapter, and the book, we will discuss the forces that play a role in defining a suitable software architecture for (object-oriented) Web applications. Currently agents are in the focus of interest of numerous research groups  Internet,Softbots,Software,Architecture,Survey. However, one may observe a divergence between purely formal approaches and purely pragmatical approaches, that provide an operational realization of agents lacking a solid foundation.

Although many of the ideas and concepts underlying agents have been a topic of research for decades, notably issues concerning distributed systems and programming language design, the notion of agents itself hase become a major research topic only recently. A survey of agent theories, architectures and languages is given in  [ Survey]. As concerns agent theories, the main focus of attention lies on a logical analysis of intentional notions underlying the behavior o research groups  Interne t,Softbots,Software,Architecture,Survey. However, one may observe a divergence between purely formal approaches and purely pragmatical approaches, that provide an operational realization of agents lacking a solid foundation.

Although many of the ideas and concepts underlying agents have been a topic of research for decades, notably issues concerning distributed systems and programming language design, the notion of agents itself hase become a major research topic only recently.:u single agents, whereas for agent architectures issues of communication and cooperation between agents have been addressed in more detail. In  [ Survey], concurrent l ogic programming languages are considered to be the ancestors of agent languages. Of immediate relevance for our own work is the Oasis programming language described in  [ Oasis], which bears a close resemblance to the distributed logic programming language DLP  [ DLP]. Recently, commercial agent systems have been developed for the Web. For example, General Magic has launched its Telescript Agent System, a system that employs mobile agents defined in General Magic's Telescript language. Also in  [ Internet], a number of agent-like programs are described. We are reluctant to qualify these systems as 'agents', however, since they are defined in a purely operational way. We find, for complex agents anyway, a more explicit representation of the intentional aspects desirable.

In a recent issue of the CACM( 37(7), July 1994), some current trends and applications of agent research are presented. From our perspective we consider as important representatives of ongoing research:  [ Software], that describes the agent communication language KQML (Knowledge Query and Manipulation Language);  [ Architecture], which describes the complexity of integrating collections of agents; and  [ Softbots], which describes a number of simple agents for facilitating access to the Web.



[] readme course preface 1 2 3 4 5 6 7 8 9 10 11 12 appendix lectures resources
eliens@cs.vu.nl

draft version 0.1 (15/7/2001)