Server Push
or „How to initiate client side changes from the server
without polling every second or so“
Donnerstag, 11. Juni 2009

Websocket
Donnerstag, 11. Juni 2009

HTML5
Donnerstag, 11. Juni 2009

var myWebSocket = new(\"ws://www.websocket.org\");
myWebSocket.onmessage = function(evt)
{ alert( \"Received Message: \" + evt.data); };
Donnerstag, 11. Juni 2009

Can you use it?
Donnerstag, 11. Juni 2009

IE6 (released 2001) market share May 09:
~15%
Donnerstag, 11. Juni 2009

No!
Donnerstag, 11. Juni 2009

Then what?
Donnerstag, 11. Juni 2009

Juggernaut
Donnerstag, 11. Juni 2009

needs flash
Donnerstag, 11. Juni 2009

no thanks
Donnerstag, 11. Juni 2009

Comet
Donnerstag, 11. Juni 2009

general technique, no implementation
Donnerstag, 11. Juni 2009

longer connections
Donnerstag, 11. Juni 2009

server and client side components
Donnerstag, 11. Juni 2009

server side
Donnerstag, 11. Juni 2009

traditionally (think Apache):
one thread per connection
Donnerstag, 11. Juni 2009

Comet servers
reduce server-side resources per connection
• Reduce overhead per thread
• use event libraries
• use microthreads (e.g. Erlang)
Donnerstag, 11. Juni 2009

client side
Donnerstag, 11. Juni 2009

asynchronous request
Donnerstag, 11. Juni 2009

hold it!
Donnerstag, 11. Juni 2009

drop connection after receiving something useful
Donnerstag, 11. Juni 2009

then reinitiate connection
Donnerstag, 11. Juni 2009

still request/reponse
Donnerstag, 11. Juni 2009

BUT
data flow occurs on the server‘s schedule
close approximation of the server → client flow
Donnerstag, 11. Juni 2009

Implementations
Donnerstag, 11. Juni 2009

Bayeux
Donnerstag, 11. Juni 2009

standard protocol
Donnerstag, 11. Juni 2009

many servers use it
Cometd
ErlyComet
GlassFish
Jetty
Orbited
Persevere
...
Donnerstag, 11. Juni 2009

many client libs use it
Dojo (inventor)
jQuery
GWT
...
Donnerstag, 11. Juni 2009

combine any server and js lib
Donnerstag, 11. Juni 2009

Jabber
Donnerstag, 11. Juni 2009

JS libs available
Donnerstag, 11. Juni 2009

mature Server
Donnerstag, 11. Juni 2009

scales
Donnerstag, 11. Juni 2009

can hold ten thousands connections on a single server
Donnerstag, 11. Juni 2009

proprietary solutions
Donnerstag, 11. Juni 2009

RMDS2Web Server
500.000 concurrent users on single Dell-server
\"most scalable real-time push web system\"
commercial
Donnerstag, 11. Juni 2009

APE (Ajax Push Engine)
\"Real time data streaming\"
open source client and server
proprietary protocol (NOT Bayeux)
Donnerstag, 11. Juni 2009

Who is doing it?
Donnerstag, 11. Juni 2009

Facebook
Meebo (Chat)
...
Donnerstag, 11. Juni 2009

That is all!
Donnerstag, 11. Juni 2009

Reminder:
Rails-Konferenz call for papers deadline:
1st of July
Donnerstag, 11. Juni 2009