Summary of design requirements

To summarize, we had to build a system that met the following requirements. To succeed, every criteria had to be met in full:

• The system had to operate in real-time. Data entered at one site must be immediately available at all other sites.
• The system had to be secured against eavesdropping, wire-taps, etc.
• The system had to be responsive to users even when communication latency was high (on the order of 1-3 seconds) and the bandwidth was low (at most 30kbps).
• All administration had to be handled by a trained end-user.
• Access to the data had to be strictly controlled and the rules for access control were subject to modification by the user-administrator.
• Access to data had to be logged and the detail with which logs were made had to be subject to run-time control by the user-administrator.
• The client user interface had to be very intuitive - users with no computer experience (literally: where's the on-switch?) had to be able to use the system after a 1/2 hour of training.
• The system had to be inexpensive to develop, deploy, administer and maintain.

The last criterion makes the preceding ones even harder to achieve!