The existing HMS system is used for many other purposes beyond just dorm room assignments. So DAO must co-exist with, rather than replace HMS, and this co-existence imposes some overhead.
Using the new approach requires: Executing six queries to export the data out of HMS, logging into a Unix system, running the DAO, and importing the data back into the master system (page ).
An HMS assignment run, using a special set of rules (Appendix A) that say `just take our suggestions', actually performs the assignments. Instead of updating HMS tables directly, we use this round about procedure to avoid voiding the `warranty'. This last step, which runs on a local copy of HMS to avoid network overhead, takes about 30 seconds per student on a 350MHz workstation. As mentioned in , the HMS roommate logic is not rule-based, and thus we cannot alter it by changing the HMS rules. However, we discovered that emptying the roommate database on the local copy rendered the overpowering HMS roommate logic harmless.
Finally, five occupant related files are uploaded to the master copy to complete the assignment process. These final steps in the process are streamlined with the use of batch files selected through window system shortcuts.
A benefit of this approach is that nothing in the master system changes until the data is imported and the master database need not be locked for the entire duration of the assignment process. The DAO can easily run during normal business hours. Besides running in less time, without weekend restrictions, results become available in a timelier manner.