Agent Interaction SDK services

[Tinu]

Hi,

I'm using Agent Interaction SDK services (.Net)  for developing a sample agent desktop .i need help on identifying
1.whether an agent is already logged in with some other extension or
2. the extension is used by another agent

basically it has to display an error message when trying to do the agent.login() method.

Plz let me know if there are any reference docs..

Thanks in advance