The builtin session management system tries to detect if the remote client is a web robot. If a robot is detected, session management is temporarily disabled and in particular no new session are generated. There are several reason why it is preferable to disable session management with web robots:
Web robots are detected by comparing their "User-Agent" http header with a database of known web robots. Draco comes with a web robots signature database that was updated dec. 2002 from the site http://www.robotstxt.org. It includes most web robots currenly active on the Internet. The database is located in the file robots.ini in Draco's data directory.
You can add signatures to this list by putting a file named robots.ini in the document root of your web site. Signatures from this file are added to the global database. The format of this file is as follows: empty lines and lines starting with a hash mark (#) are ignored. Other lines contain a string with is prefix matched with different parts of the "User-Agent" header. An example:
# Small robots.ini example. # These signatures are already present in Draco's # web robot database, no need to add them yourself. jeeves googlebot openfind data gatherer