Harmony for Microsoft Exchange 2000 uses WebDAV technology to connect to the Exchange 2000 server. WebDAV offers superior performance for Exchange 2000 users over CDO. Installed on a Java Virtual Machine, Application Server or Servlet Engine, Harmony for Microsoft Exchange 2000 brings the mail, calendar, task, contact, journal, public folders and Global Address List information from the Exchange 2000 server to a web browser or mobile device and store any changes to that information back on the server.
The WebDAV-related products I've mentioned here recently are by no means the only WebDAV products out there, just those Ive seen that are specifically targetted at Exchange 2000. For details of more generally WebDAV-related products and projects the WebDAV Resources page is well worth a browse.