Web Development with Clojure, 3rd Edition

Multi-User with WebSockets

Instead of just having a refresh messages button, let’s add a push notification for new messages using WebSockets.

We’ll take a look at using WebSockets for client-server communication. In the traditional Ajax approach, the client first sends a message to the server and then handles the reply using an asynchronous callback. WebSockets allow the web server to initiate the message exchange with the client.

Currently, our guestbook application doesn’t provide a way to display messages generated by other users without reloading the page. If we wanted to solve this problem using Ajax, our only option would be to poll the server and check if any new messages are available since the last poll. This is inefficient since ...