Hi Sunil,
In the future, please post to the Premium Downloads section:
http://www.infopathdev.com/forums/forum.asp?FORUM_ID=47 I'm not sure what you mean about "send only the link and not the entire form in e-mail". This sounds like an InfoPath question and not an AD Web Service question. If you are just taking about the e-mail adapter, then you can do this by inserting the link into the body of the message. You may need to write some code to do this but first check the design wizard - there may be a setting. It's a fairly common practice, though.
The service returns the current logged in user. It also has functionality to check the user. It does not currently return a list of all users and that would be difficult since some organizations have thousands of users.
Patrick Halstead [InfoPath MVP]
InfoPathDev