Doc-U-Lib: About

Introduction

• perl
  
  
• "standard" CGI, so not persistent (contrast FCGI).

Database

• The cgi-scripts interact with the database through CDF.pm, Thingy.pm and Tree.pm, three OO modules. These provide an abstraction layer so that the database can be changed without affecting the client-related code.
  
  
• Currently the database is very simple: we just use the file-system on the (unix/linux) server and some SGML files. This is not particularly efficient, but is simple and plenty fast enough for a few dozen users with a few thousand files. Should an improvement be necessary, we can consider DBM files, SQL...

Authentication, the Password Abstraction-Layer/Subsystem

• Once authentication has taken place a cookie is set which lasts for the current browser session only.
  
  
• Authentication is by username/password. The current implementation uses a password directory, PASSWD, in which password files reside. These files include usernames, encrypted passwords and names of groups in which users belong. More than one password file can be used. For example, one for permanent, development staff, one for temporary guests, ...
  
  
• The cgi-scripts interact with the username/password/group directory through _sal/Passwd.pm an OO module which provides an abstraction-layer, thus the whole system could be changed to use, e.g., LDAP-authentication, with ease.

Exception Handling

Perl's error detection is good but it's error handling is not up to that required for a safety-critical system, nor indeed a document repository. So I wrote a simple exception handling mechanism (_lib/exceptions.pm).

Depending upon the severity of the exception raised various things can happen, from a simple message to the user to a forced exit.

All raised exceptions are logged.

Logging

A logging mechanism (_lib/log.pm) is used to keep a check on various events. These include all raised exceptions.

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