Socket.IO, etc all require the using of browser on the client side....just wondering, how can we have browserless websocket client for node.js ?
A Node.js server is in no way bound to a web browser as a client. Any program can use whatever socket library is provided by its supporting libraries to make a call to a Node.js server.
EDIT
Responding to your comment: don't forget that Node.js is Javascript! If you want to execute code periodically -- in much the same way that a daemon process might -- you can use setInterval to run a callback every n milliseconds. You should be able to do it right there in your node program.