Live geolocation web app android

I want to create a node.js web app that when you select a user from a list shows you its location in real time. The user has to get the Android Application activated.

I know how to do the android application, but the part of the web application I don't know how to raise it.

The only thing that occurred to me is to keep the location in a database table and a web socket get the position of the user.

An example of what i want is Runtastic on live.

Thanks.