how to get user name of the client machine

[vikas sharmaa]

we can get the name of current user logged in to the system by using System.getProperty("user.name") method call. But, how could we get the user name of the client machine from the server machine? here client is sending request to server machine using browser. On getting first request, server has to determine the user name of the client. we are not using applets in our application. Please help me. Thank you.

[Rob Spoor]

Let the client send the user name along with the rest of the request. The server can't possibly know who the user is unless someone told him so.