The ASP should accommodate many users, as well as few, and multiple parties. There should be a clear protocol to add and remove users. Investigate the underlying database engine and learn its upper and lower limits. Besides log-in passwords, encryption, and digital certificates, some systems use an electronic security token that generates a new ID number every 60 seconds. You may be asked at any time to re-verify your ID number, but the added security is worth it.
Many ASPs offer integrated applications that range from private calendars to matter management.
Make sure your ASP has a high-bandwidth throughput. Then make sure YOU have one, too. Don t forget that users will sometimes be dialing in on modems.