I recently felt the power of SIP-based presence in our Syracuse University Real-World Labs®, where I took Microsoft's Live Communication Server 2005 and its companion Communicator 2005 for a spin.
First, I installed LCS on a dual-processing Intel Xeon CPU (3 GHz) with 3 GB of RAM running Windows 2003 Server. In IETF parlance, LCS is a presence server that combines the activities of a PA (presence agent), a registrar server and a proxy server for SUBSCRIBE requests.
In my tests, LCS acted as a PA for two instances of Communicator 2005 running on Windows XP from an IBM Thinkpad T-41 and a Sony Vaio (PCG-R505ECP). LCS also exchanged SIP messages with a public IM provider and AOL Instant Messenger after I enabled Federation. (The Federation feature lets LCS exchange SIP messages and track the presence of users outside my skyey.nwc.com domain with AOL Instant Messenger).
To keep track of the SIP presence information and transactions, LCS must run on Microsoft SQL Server. I also used Active Directory for the users participating in the sessions. Once I prepped the forest and domain with LCS schema extensions and installed the requisite files (2 MB to 3 MB), I deployed a new tab in the Active Directory Users and Computers console (dsa.msc) that enabled Live Communications for users. I identified the SIP URI for the users "sdoherty" (sip:[email protected]) and "randerson" (sip:[email protected]) and associated them with the LCS enterprise pool I created during installation.
The enterprise pool, which is the PA, identified the SQL server instance for the presence information, and information on remote servers used to proxy SIP requests to remote servers. The PA also contained information for archiving IM sessions and tracking archive server resources via WMI (Windows Management Instrumentation) and Windows Performance Manager--so you can archive AOL IM sessions using LCS, for instance.
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