server push and comet (rails user group hamburg 2009-06-10)

Server Pushor „How to initiate client side changes from the server

without polling every second or so“

Donnerstag, 11. Juni 2009

Websocket


HTML5


var myWebSocket = new("ws://www.websocket.org");myWebSocket.onmessage = function(evt)

{ alert( "Received Message: " + evt.data); };


http://www.websocket.org

http://www.websocket.org

Can you use it?


IE6 (released 2001) market share May 09:

~15%


No!


Then what?


Juggernaut


needs flash


no thanks


Comet


general technique, no implementation


longer connections


server and client side components


server side


traditionally (think Apache):one thread per connection


Comet serversreduce server-side resources per connection

• Reduce overhead per thread

• use event libraries

• use microthreads (e.g. Erlang)


client side


asynchronous request


hold it!


drop connection after receiving something useful


then reinitiate connection


still request/reponse


BUT

data flow occurs on the server‘s schedule

close approximation of the server → client flow


Implementations


Bayeux


standard protocol


many servers use it

CometdErlyCometGlassFish

JettyOrbited

Persevere...


many client libs use it

Dojo (inventor)jQueryGWT

...


combine any server and js lib


Jabber


JS libs available


mature Server


scales


can hold ten thousands connections on a single server


proprietary solutions


RMDS2Web Server

500.000 concurrent users on single Dell-server

"most scalable real-time push web system"

commercial


APE (Ajax Push Engine)

"Real time data streaming"

open source client and serverproprietary protocol (NOT Bayeux)


Who is doing it?


FacebookMeebo (Chat)

...


That is all!


Reminder:

Rails-Konferenz call for papers deadline:

1st of July


server push and comet (rails user group hamburg 2009-06-10)

Technology