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In the case of the link with commentary, the term ‘link’ is used even though it is not a real link, due to the fact
it does not relate to two nodes of the hypertext but to a node that is connected to a commentary page (this is the
reason why the acronym ‘SC’ signifies ‘Simple commentary’). A personalised link is public or private. The
public link, in opposition to the private link, means that the author’s work can be accessed by other users.
The General Architecture
The Web uses the CGI (Common Gateway Interface) [Mc Cool 94] that serves the purpose of writing the
bridges between the information HTTP servers (HyperText Transfer Protocol) and external programs. The role
of these programs, that are commonly known as scripts, consists of : (i) capturing the parameters entered by the
user, (ii) manipulating them and, (iii) giving a result to the client program that made the request. The
architecture chosen for ‘Nestor’ is based upon the coupling of Matisse [2] , an objet oriented database, and
Netscape, a client of the Web. The interfacing of these two applications is assured by scripts written in Python,
an objet oriented programming language developed at the ‘Centrum voor Wiskunde en Informatica’ (CWI) of
Amsterdam [Van Rossum 93].Matisse is asystem used for the managment of object oriented databases. Its basic
concept is the PDM model (Property Driven Model), developed at the University of Technology of Compiègne
[Barthès et al. 86]. This model is based upon both semantic networks [Quillian 68] and frames [Minsky 74].
An object is characterised by two different properties : the attributes and the relations. The notions of minimal
and maximal cardinality are associated with the relations, as occurs within the Entity-Association data model
[Chen 76]. From a practical point of view, it is possible to note the following :
• all values added to the documents are systematically assigned a signature that comprises the date at which
these improvements have been performed, and the name and electronic address of the author.
• the creation of a personalised link is both simple and dynamic. In the first instance, the author selects the
line, and then the word, that will play the role of anchor. Secondly, the ‘Destination’ and ‘Commentary’
fields enable him to classify the links (cf. the end of section 3.2).
• the equality approach, that consists namely of all the users having access to operations in order to improve
documents, is only verified for the members of CNET. This explains the requirement for the use of
personal passwords within Matisse, in order to identify users. Whilst using ‘Nestor’ with a password that
has the specific value ‘anonymous’, an external CNET user would be able to, nevertheless, consult the
recommendations and all the additions before they are declared public.
Python is an interpreted programming language that proposes objects and high level operations using a simple
syntax that is based upon indentation. In addition, it has the advantage of possessing a standard ‘CGI’ module
that allows the easy capture of parameters from a HTML page. The following modules have been written for
‘Nestor’ :
Matisse
Within this module are the main functions (written in C) of the Application Programming Interface of Matisse.
FormatHtml
This module embodies a part of the HTML language. This language is used for the diffusion of documents by
Web servers and consists of a set of formatting commands.
Compiler
The compiler allows the transformation of the set of ASCII recommendations into HTML files. This
transformation is performed in two stages. Firstly, the compiler identifies the units (or nodes) of the hypertext,
[2] Matisse (Multimedia Advanced Technology for Information Systems Semantic Engineering) is a trademark of ADB the
society (Advanced Data Base).