From CD-ROM to Web-Served: reverse engineering of an interactive Multimedia Course Daniele Maraschi LIRMM, Montpellier, France
[email protected]
Stefano A. Cerri LIRMM, Montpellier, France
[email protected]
Abstract The Web offers advantages for Learning Technologies, but the interactivity necessary for the learner requires technical features that are currently hardly supported. In the paper, we briefly describe how a traditional Multimedia Course, usually marketed as off-line CD-ROMs, has been reverse engineered to a server-based, multi-client Web application in order to have an identical behaviour at the learner's site. The new Course consists of XML/XSL documents programmed by server-driven Java functionalities managing the conversations with the remote learners. Abstraction and generalisation to other Courses and/or interactive Web applications or services, become now feasible, easy and re-usable, because all middleware technologies are Open Source.
1. Introduction Advanced Learning Technologies (ALTs) today are those that support Learning by stimulating it through Dialogues with Systems[1]. These may range from the simplest, locally loaded program, to Web applications where Artificial and Human Agents collaborate to animate the Dialogues. A wide range of architectures may be conceived for Systems adequate to support Learning: from Tutoring Systems to Learning Environments; each of these may be based on a client-centred or server-centred approach. In this paper we consider an existing available Course, designed, developed and marketed since years on CDROMs; we present why it is convenient to transform it into a dynamically generated, interactive, multimedia, server-centred Web application and we summarise how we did the porting to the Web.
2. A conversational view of the Web in ALT The Web as an interactive, multimedia Communication medium is currently hindered by a major limit: its behaviour is mainly page-centred as HTTP is a stateless protocol. In interactive Web applications, such as those that support Human Learning, this limit has to be overcome. In recent papers [e.g.: 2] a serious approach to advocate a computation-centric view of servers (in opposition to the usual page-centric) has shown that continuations may model multiple conversations between users and a Web server preserving the state of the conversation by means of an extremely simple mechanism of continuations like the one available in the
Gianna Martinengo Didael SpA, Milano, Italy
[email protected]
Scheme programming language. We agree with this view, so deeply that we have proposed a perfectly complementary model - called STROBE - for modelling Agent to Agent Conversations [3-5]. However, Lisp or Scheme are not widely used applicative languages, even if we believe they are best adequate for Web applications [6]. Looking at the literature, the porting to the Web of available Intelligent Tutoring Systems (ITS) has been reported in cases where a LISP-HTTP server has been used, compatible with the Lisp code of the ITSs [7-8]. Surveys about Web-Based Education do not present other examples of Web-Generated Courses at the moment [9]. On the contrary, a rapidly growing number of examples of Web-Generated Interactive Web Sites are currently reported [10].
3. How we did the porting to the Web In order to publish XML documents on the Web without any kind of plugin, we have chosen a servletbased Java framework, Cocoon [10]. In such a way, the two steps of a) parsing the XML content and b) interpreting the XSL layout in order to obtain HTML pages, are executed on the Web server each time the page is requested by the user. The use of Java servlets allows to manage user sessions in a simple yet efficient fashion. This management requires the persistence of at least one data structure, modelling the user state during the whole period of interaction between the user and the Web application. At the moment the Cocoon framework allows to program both XML and XSL documents using the Java programming language. Starting from three CD-ROMs containing a Toolbook application, generating a proprietary Multimedia Course to learn the Italian Language, we have classified all the possible types of pages (the menus, the presentations including multimedia components and the exercises) and, for each of them, we have built the corresponding XML structure along with a series of XML/XSL documents apt to generate the output layout of the XML content. The new source code amounts to about 750Mbytes. We encountered two types of obstacles, each corresponding to a class of problems: conceptual and engineering problems. The conceptual ones concern the reverse design of an XML structure reflecting «potentially» the results of a Toolbook application. We could have adopted here: a) the approach of redesigning the XML tree structure with our own
Proceedings of the IEEE International Conference on Advanced Learning Techniques (ICALT’01) 0-7695-1013-2/01 $10.00 © 2001 IEEE
mental model of how, later, the XSL and Java code would have had to be developed in order to have the final HTML pages, or b) the approach of maintaining the «semantic» structure underlying the Toolbook application, so that the final Web product would have exactly the same appearance as the original CD-ROM based Course. We have preferred the second option for market reasons. Since the CD-ROM Course is a success, clients are used to it, so that in this first experience we preferred to limit as much as possible the modifications on the interface. The engineering problems concerned the acquisition and mastery of the relevant languages and tools and their integration. This was not really beyond our scope, as we are currently developing an integrated Environment for both Agent architectures and Web Applications [11]. Among the interesting engineering challenges, we implemented a Java-based protection functionality that allows specific XML files to be decrypted-encrypted on the fly at runtime.
4. Foreseen developments and conclusions The product will be delivered in the next weeks.1 The evident advantages of the porting in terms of reuse of methods and tools in the design and development phases are clear from the separation, in the reported architecture, of the concerns regarding the document structure (XML), the page layout (XSL) and the user interaction (Java). Once a Course is published on the Web, it is easily conceivable that other features can be integrated, such as those offered by the ATHENA© Platform [12]. The evident advantages of the porting to a server-based Web application for the Course delivery phase, consist of the world-wide offer to learners that, on turn, may well feed back the results of user's evaluations (managers, teachers as well as students) to the designers and developers for generating subsequent, more powerful versions. The next endeavour is to integrate tools so that remote human teachers, experts, designers may modify dynamically the « teacher Agent » according to evolving specifications, in such a way that a minimal technological expertise is needed even for updating the Course [13]. After 30 years a content independent Authoring System becomes a feasible goal. We foresee, however, that such an achievement will require really integrated Agent Technologies [11]. As a conclusion, we argue that these innovative operations require, at the moment, highly skilled human resources. The difficulty is not in terms of personmonths (six p.m. in our case) but in terms of « culture » ; technical awareness and familiarity with a variety of concepts and tools that Web processing requires/offers (see for instance www.sourceforge.net). 1 We hope to be able to demonstrate it at the Conference, including its performances, expected to range between 100 and 1000 interactions per minute.
These concepts and tools are not in the standard background of our graduates in Computing, at least insofar they are not part of standard curricula but have to be acquired by self learning.
5. Acknowledgements We are grateful to Didael SpA for having stimulated, supported and facilitated our endeavour. The work described in this paper was part of the EU INCOCOPERNICUS project LARFLAST (LeARning Foreign LAnguage Scientific Terminology).
6. References [1] S. A. Cerri, "Models and Systems for Collaborative Dialogues in Distance Learning", Collaborative Dialogue Technologies in Distance Learning , vol. 133, ASI Series F: Computers and Systems Sciences, M.F. Verdejo and S. A. Cerri, Eds. Springer-Verlag, 1994, pp. 119-125. [2] C. Queinnec, "The Influence of Browsers on Evaluators or, Continuations to Program Web Servers", International Conference on Functional Programming, ACM. Montréal, Canada, Nov. 2000. [3] S. A. Cerri, "Computational Mathetics Toolkit: architecture's for dialogues", Intelligent Tutoring Systems, vol. 1086 in LNCS, C. Frasson, G. Gauthier and A. Lesgold, Eds. Springer-Verlag, 1996, pp. 343-352. [4] S. A. Cerri and D. Maraschi, "Dialogues among Distributed Agents", Workshop on Advances in Languages for User Modelling, 6th International Conference on User Modelling, S. A. Cerri and V. Loia, Eds., Chia Laguna, Sardinia, Italy, 1997. [5] S. A. Cerri, "Shifting the focus from control to communication: the STReams OBjects Environments model of communicating agents", Collaboration between human and artificial societies, vol. 1624 in LNAI, J. Padget, Ed., Springer-Verlag, 1999, pp. 71-101. [6] S. A. Cerri, "Dynamic typing and lazy evaluation as necessary requirements for Web languages", European Lisp User Group Meeting, Amsterdam, NL, 1999. [7] P. Brusilovsky, E. Schwarz, G. Weber, "ELM-ART: an Intelligent Tutoring System on World Wide Web", Intelligent Tutoring Systems, vol. 1086 in LNCS, C. Frasson, G. Gauthier and A. Lesgold, Eds. Springer-Verlag, 1996, pp. 261-269. [8] A. Mitrovich and K. Hausler, "Porting SQL-Tutor to the Web", Workshop on Adaptive and Intelligents Web-based Education Systems, ITS'2000, Montreal, Canada, 2000. pp. 3744. [9] S. R. Alpert, M. K. Singley, P. G. Fairweather, "Deploying Intelligent Tutors on the Web: an Architecture and an Example", International Journal of AI in Education, 10, 1999, pp. 183-197. [10] Cocoon. http://xml.apache.org/cocoon/ [11] D. Maraschi, "Jaskemal: a Java/Scheme based integrated Framework to develop Web Application and Intelligent MultiAgent Systems", PhD Thesis, LIRMM, University of Montpellier II, France, 2002. (in preparation) [12] The Atena Platform. http://www.didael.it [13] S.A. Cerri, S. Dikareva, D. Maraschi, S. Trausan-Matu, "Web Server Based Architectures for Language Learning: LARFLAST Agents generating CALL Dialogues", Conference on Computer Assisted Language Learning, Univ. of Exeter, UK, September 2001. (accepted)
Proceedings of the IEEE International Conference on Advanced Learning Techniques (ICALT’01) 0-7695-1013-2/01 $10.00 © 2001 IEEE
