1 Introduction

Navigation across the Internet consists of jumping across a set of links interactively chosen by the user during a session with an Internet browser. This may be arduous because of the absence of an effective classification scheme for the enormous amount of information available through billions of inter-linked UNIFORM RESOURCE LOCATORs (URLs). Altogether, this huge world-wide ``information system'' has the structure of an untyped semantic network [5]. The basic idea put forward in this paper is to use the SOUR software system as an Internet Navigation Assistant. SOUR is a system for comparing, classifying and retrieving information about large software systems. Figure 1 depicts the overall structure of the system [16][15][14][18][17][19].

Figure 1: SOUR Overall Architecture

The unit of information in SOUR is the so-called Abstract Object (AO), a notion which combines the enumerative and faceted classification schemes [10][11][12] as an extension of the popular attributive view of objects in the context of a hierarchical semantic network information model.

A crucial decision to make is how to map Internet nodes onto the SOUR information model. A URL refers to the format used by World Wide Web (WWW) [21] documents to locate files on other servers. A URL gives the type of resource being accessed (e.g., gopher, WAIS), the address of the server and the path of the file. The format is

scheme://host.domain[:port]/path/filename

where scheme is one of

file	file on your local system, or a file on an anonymous ftp server
http	a resource on a World Wide Web server
gopher	a resource on a Gopher server
WAIS	a resource on a WAIS server
news	an Usenet newsgroup
telnet	a connection to a telnet-based service

The above information scheme can be turned into a SOUR class scheme in a way that will be described in this paper. But a summary of the overall SOUR information model will be presented beforehand.