Technical Aspects of the WWW, the Integrator of "Cyberspace"

In order to discuss ``when the Web'' works in education, let's recall shortly ``how the web'' works. The World-Wide Web was conceived by Tim Berners-Lee at CERN in 1989 as an information integrator within which all available information on the Internet could be accessed in a simple and consistent way on every kind of machine architecture. A standard WWW browser (i.e. the client program for the WWW) can access at least the following communication protocols: HTTP (WWW's Hypertext Transfer Protocol), FTP, NNTP, WAIS and Gopher. Central for information retrieval is the Universal Resource Locator (URL). A URL (e.g. ``http://tecfa.unige.ch/welcome.html'') is composed of a protocol indicator (e.g. ``http''), an Internet machine name (e.g. ``tecfa.unige.ch'') and a file name (e.g. ``welcome.html''). Usually the file name stands for a document to be retrieved. Sometimes, a program will be launched, e.g. ``http://www.ucc.ie/htbin/acronym'' will launch a program for looking up Internet Acronyms). Note that in principle any networked software can be turned into an HTTP server and this is important for future educational WWW-based systems.

The standard WWW information vehicle is a hypertext document, a text file encoded with the so-called ``Hypertext Mark-Up Language'' (HTML). An HTML file will display on your screen according to special mark-up commands and according to the settings and capabilities of your client-program. Special highlighted buttons in a displayed ``page'' allow retrieval of other pages from anywhere in the world (including any kind of file formats that your setup can handle).

The server tells the client what file type is accessed. When a file format is met that the browser does not understand (e.g. a Postscript, a VRML or a Toolbook file), a ``helper'' application is called, if it is available on your machine. You can configure your client to use any kind of program to display any multimedia image, sound, video and data format. Note also, that most WWW clients can display in-line images. HTML is an evolving language: The latest version (HTML 3) allows for quite sophisticated layout (e.g. tables, text floating around images).

Forms are an important feature of HTML. They allow a server to query the user with a few standard graphic user interface (GUI) widgets like push-buttons, radio-buttons, text editing window and scrolling lists. This information can then be processed by the server. It makes up a powerful query-interface to various kinds of data bases, but it can be used as interface to any program running on a server. Because HTML pages can be generated dynamically by a server, such pages can be tailored according to the needs of the user, which is an interesting feature for educational systems. Another feature is interactive maps which report to the server the position of mouse clicks. Such maps can be used to build user navigation aids.

Given this technical description, the WWW can be characterized with several functionalities:

1. A Knowledge Integrator
2. A distributed Hypertext
3. An Interface to any kind of remote program
4. An Interface to certain local programs

For producing HTML, there are 4 basic strategies:

1. Using a simple text editor (inserting html tags manually),

2. Using a ``smart'' text editor or an HTML tool that includes special editing extensions for automatically inserting HTML tags (like HTML assistant for Windows; or an ``HTML tool'' like HotMetal)

3. Using ``filters'' (translation programs that translate from text or other formats into HTML)

4. Using programs that create HTML ``on the fly'' (a feature frequently used to display output resulting from a data base request, on-line questionnaires and assessment programs).

Option 1 is not very productive, Option 2 is best for producing short Hypertext material, but using those tools requires some training. Option 3 is a good solution for producing larger document structures that also can be printed. However, currently these filters are not powerful enough (especially in the world of micro-computers).

We can distinguish several levels of WWW Use in Education. In order of difficulty they are:

1. The Web as information tool: Curricula and courses information, etc.)
2. Distribution of learning material: E.g. books (in various formats like postscript, word-processor, etc.), programs, applications needing a specific interpreter/language for the client
3. Collaboration tools
4. Interactive educational applications:

The realization of level 3 and level 4 WWW-interfaced applications are hindered both by the design of the WWW and the fact that advanced programming knowledge is required.

Recently a few interesting new developments can be observed in the WWW world, like: HotJava (a WWW client that can execute programs), WWW-MOO interfaces, VRML (virtual reality mark-up language) interfaces, Netscape's ``server-pushes'', Educational packages for CGI-scripts. These extensions and additions will add additional power to the WWW and increase its popularity.