The Browser Server Protocol

The Browser server protocol is extremely simple. It makes use of JSON messages sent over a websocket. This fits nicely with both Erlang and JavaScript and makes interfacing the browser to Erlang really easy.

Sending a Message from Erlang to the Browser

To change something in the browser, we send a message from Erlang to the browser. Suppose we have a div in the browser, declared like this:

 
<div​ id=​"id123"​​>​​</div>

To change the content of the div to the string abc, Erlang sends the following JSON message to the websocket that is connected to the browser:

 
[{cmd:​'fill_div'​, id:​'id123'​, txt:​'abc'​}]

The code in webserver.js, which is activated when the browser receives a message from a websocket, is a callback ...

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