Question

I want to make realtime change in HTML documents.

When the variable changed with event, HTTP document(.erb file) must automatically change together.

#controller.rb

puts("Downloading...")

bt = RubyTorrent::BitTorrent.new("public/files/ubuntu.torrent")
bt.on_event(self, :complete) { @donemessage="Done!" } #<-- This event


#index.html.erb
<h1>Transfers</h1>
<p><%= @donemessage %></p> <!-- <- This must be changed -->

How can I do that?

Answer 1

This is not an easy task at all. But generally the approach is following:

1. client (for simplicity, think of a browser) should tell server that it wants to know about the state change of a given object(s); i.e. it wants to be subscribed to listen events that occur on certain objects;
2. all objects that might change their have states should be put in special queue;
3. on the server side, the queue resolver, after processing given (next) object in queue, should notify all subscribed client about the new status of object.
4. Now that clients are notified, they can make further actions based on the new data about objects they received. For example, client can update the part of html of the page.

Again, I cannot speak in details here as this is not that simple.

Take a look at the following projects to get more info on the topic:

1. Meteor
2. EventMachine