Use Drupal login with an opensource billing app

Hello, My client is currently running a Drupal 6 website. They would like to start using another application for billing clients called Ofuz. The job is to synchronize logins and users between drupal and Ofuz. Please see details below for more information. ## Deliverables My client is currently running a Drupal 6 website. They would like to start using another application for billing clients called Ofuz. (You can download it from: [login to view URL] and Installation instructions are here: [login to view URL]) Ofuz has its own login authentication and user tables. *The functionality the client needs is:* * When logged into Drupal, Ofuz should be accessible. When logged out of Drupal, Ofuz should not be accessible. * When accessing Ofuz, the script should check to see if a user with the same drupal id or drupal name already exists, and if not, create that user in the Ofuz database. The objective is so that salesman1 can invoice his clients and salesman2 can invoice his clients separately. Ofuz should not lose its multi-user capabilities. * Finally, within Ofuz, there is the possibility for a user to add a new "coworker". This basically adds a new user to the "user" table in the ofuz database. When this happens, we would also like the user to be added to the Drupal user database with the same credentials. *Some guidelines:* * The drupal core should not be altered. * Changes to Ofuz files are fine but a list of all files altered must be provided so that when a new version of Ofuz is released, the client can copy over the changes. * Changes made to Ofuz files should be labelled with comments. *Notes:* At the moment, Ofuz doesn't work when installed in a subdirectory (ie [login to view URL]). It needs to be installed as something like ofuz.mysite.com. This presumably means that the sessions will have to be shared between domain and subdomain. Ofuz allows users to login with their facebook/google/twitter accounts but this functionality does not need to be preserved. You probably already know this but just in case it helps, Drupal allows logins from external applications. There are sample scripts out there that may help: [login to view URL] If you have any questions, please feel free to ask.