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eventsource.html
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eventsource.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Eventsource</title>
<meta name="apple-mobile-web-app-capable" content="yes" />
<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<link rel="stylesheet" href="lib/reveal.js/css/reveal.min.css">
<link rel="stylesheet" href="lib/reveal.js/css/theme/night.css">
<link rel="stylesheet" href="lib/template.css">
<!-- For syntax highlighting -->
<link rel="stylesheet" href="lib/reveal.js/lib/css/zenburn.css">
<!-- If the query includes 'print-pdf', include the PDF print sheet -->
<script>
if( window.location.search.match( /print-pdf/gi ) ) {
var link = document.createElement( 'link' );
link.rel = 'stylesheet';
link.type = 'text/css';
link.href = 'css/print/pdf.css';
document.getElementsByTagName( 'head' )[0].appendChild( link );
}
</script>
<!--[if lt IE 9]>
<script src="lib/reveal.js/lib/js/html5shiv.js"></script>
<![endif]-->
</head>
<body>
<div class="reveal">
<div class="slides" id="content">
<section data-markdown
data-separator="==="
data-vertical="---"><script type="text/template">
# 20 minutes to create a chat
---
<img src="eventsource/assets/cat.png"/>
---
# ... in Ruby
===
* **Rails :** Create a **blog** in 20 minutes
* **Angular :** Create a **TODO list** in 20 minutes
* **Node :** Create a **chat** in 20 minutes
===
## Websockets / SSE
---
* Open connection
* Realtime data push
---
### Websockets
* 2-way channel (realtime push **TO** the browser)
* Need an evented server
* IE 10+
* Obscure protocol
---
### Eventsource / SSE
* 1-way chanel
* via HTTP
* TEXT!
* No IE (but fallbacks)
===
## Eventsource?
---
### Why?
* proxies-friendly (http)
* fallback to long polling
* Speaks HTTP : keep the session
---
### Spec
* HTTP with **text/event-stream** MIME type
```
data: Hello
data: World
```
```
event: add
data: 123456
event: remove
data: 456789
```
---
### Native client
```
var source = new EventSource('updates.cgi');
source.onmessage = function (event) {
alert(event.data);
};
```
```
var source = new EventSource('updates.cgi');
source.addEventListener('add', addHandler, false);
source.addEventListener('remove', removeHandler, false);
```
===
# 0. Template
---
### Client
```html
<div id="chatroom">
</div>
<form action="/message" method="post">
<input type="text" name="message" placeholder="Type your message"></input>
<input type="submit" value="Send"/>
</form>
```
---
### Backend
```ruby
require 'sinatra'
class App < Sinatra::Base
end
```
===
## 1. Open a connection
---
### Client
<pre>
<code class="html xml">
<script type="text/javascript" src="https://code.jquery.com/jquery-2.1.1.min.js"></script>
<script type="text/javascript" src="js/chat.js"></script>
</code>
</pre>
```javascript
var Chat = {
start: function(){
console.log('Joining the chat...');
var source = new EventSource('/join_room');
}
};
$(function(){ Chat.start(); });
```
---
### Server
```ruby
get '/join_room' do
content_type 'text/event-stream'
puts 'Somebody joined the chat!'
end
```
===
## 2. Ping-pong
---
### Server
```ruby
get '/join_room' do
content_type 'text/event-stream'
stream(:keep_open) do |connection|
connection << "data: Welcome to the chat!\n\n"
end
puts 'Somebody joined the chat!'
end
```
---
### Client
```javascript
var Chat = {
start: function(){
console.log('Joining the chat...');
var source = new EventSource('/join_room');
var self = this;
source.addEventListener('message', function(event){
self.appendMessage({text: event.data});
});
},
appendMessage: function(message){
var line = $('<p>');
line.html(message.text);
$('#chatroom').append(line);
}
};
```
===
## 3. Talking to people
---
### Server : store connections
```ruby
set :users, []
get '/join_room' do
content_type 'text/event-stream'
stream(:keep_open) do |connection|
puts 'Somebody joined the chat!'
settings.users << connection
# On close
connection.callback do
puts 'Somebody left the chat :('
settings.users.delete(connection)
end
end
end
```
---
### Server : dispatch messages
```ruby
def message(data)
"data: #{data.to_json}\n\n"
end
post '/post_message' do
puts "New message : #{params[:message]}"
settings.users.each do |connection|
connection << message(text: params[:message])
end
halt 200
end
```
---
### Client
```javascript
$('form').on('submit', function(e){
$.post('/post_message', $(this).serialize());
$(this).find('input[type="text"]').val('');
e.preventDefault();
});
```
===
## 4. With users
---
### Client
```javascript
var Chat = {
[...]
connect: function(name){
this.name = name;
[...]
},
sendMessage: function(messageText){
$.post('/post_message', {
text: messageText,
name: this.name
});
},
appendMessage: function(message){
var line = $('<p>');
line.append ('<strong>' + message.from + '</strong> : ');
line.append(message.text);
this.chatRoom.append(line);
}
}
```
---
### Server
```ruby
post '/post_message' do
settings.users.each do |connection|
connection << message(from: params[:name], text: params[:text])
end
end
```
===
## 5. Integration
---
* Talking via http : sessions are here!
* Deployable to a separate service / server
* redis pubsub / rabbitmq bus
* Or just plain HTTP : `post '/dispatch'`
===
## 6. Ship it!
* Evented server needed (thin + nginx)
* Heroku compatible : https://jtrubychatdemo.herokuapp.com/
---
### Nginx config
```
proxy_set_header Connection '';
proxy_http_version 1.1;
chunked_transfer_encoding off;
proxy_buffering off;
proxy_cache off;
```
===
## Links
(W3C Spec)[http://www.w3.org/TR/2012/WD-eventsource-20120426/]
(Sinatra streaming)[http://www.sinatrarb.com/contrib/streaming.html]
</script></section>
</div>
</div>
<script src="lib/reveal.js/lib/js/head.min.js"></script>
<script src="lib/reveal.js/js/reveal.min.js"></script>
<script src="lib/jquery/dist/jquery.min.js"></script>
<script src="config.js"></script>
</body>
</html>