how to open popup window on both side using javascript

I am developing a chat application here i have kept general chat room here multi users can chat wi开发者_开发技巧th each other but now i want one to one chat in my application, when logged user click on any user in the user list, one pop up window should be opened on the user computer and another pop up window should be opened in the remote users computer , how can i achieve this , any help will be appreciated...

Its possible only through ajax. javascript can play only with your browser.. when user1 starts a chat, the ajaxscript should communicate the server.. the user2 should be constanly asking the server if someuser has sent a message to him.. if yes, retrieve the message, and with javascript open a window in user2's browser..

Dont ask how to do? or ask code!! try.. if u haveproblems/errors comeback with code :) :)