Implement Comet using PHP
Dutch PHP Conference 2011Jonas Marin King Foowww.king-foo.be
Jonas Marin, King Foo www.king-foo.beAuthor Zend Framework Web
Services (php|architect)Online since 93 (yep). PHP for fun since
96, professional since 2001.Master in Biological and Genetic
Engineering, University of Leuven.
Comet=data push from server to client
Comet
aka
Reverse AjaxHTTP server PushAjax PushHTTP streaming...
abused/umbrella term
Use case
Example updates being pushed:ticker info
news items
chat messages
status updates
e-mail notifications
in-app messaging
monitoring feedback
feedback on processes that take time to complete
...
Push?
But, but ... a browser pulls and the server responds, no?
Fake push using polling trickery
Connection is kept open as long as possible
A giant hack
Does the trick for now
The Basics
Short polling
Client tries to get something new from the server and polls at
regular and short intervals.
Responsiveness at the cost of performance (on the server side).
Wasteful in terms of resources.
Easy, but not really what we are looking for.
Not considered 'comet'.
Short polling
function getUpdate() { $.ajax({ type: "POST", url: "server.php",
data: "type=news&category=PHP", success: function(msg){
$('#feed').append(msg);/** we do something **/
setTimeout("getUpdate()", 2000); } });}
$(document).ready(function() { getUpdate();}
Short polling
demo
The forever frame
An iframe keeps loading, never stops (or reloads
occasionally)
Also called streaming
Dirty, e.g IE doesn't like this
The forever frame
In the page:function updateResult(/** do something **/))
On the server:
