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Re: chat on web, Ajax ? [message #177162 is a reply to message #177161]

Fri, 24 February 2012 14:51

Tim Streater
Messages: 328
Registered: September 2010

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Senior Member

In article <4f479e77$0$6860$e4fe514c(at)news2(dot)news(dot)xs4all(dot)nl>,
Erwin Moller <erwinmollerusenet(at)xs4all(dot)nl> wrote:

> On 2/24/2012 2:59 PM, sl@exabyte wrote:

>> I am implementing chat on the web, ie on a browse. On browser, I can only
>> use javascript. So the problem is what method to use to listen for incoming
>> data.
>
> Yes.
> That is the problem: typical http requests data from some server, and
> after it arrives, that's it.
> A normal http request:
> 1) Browser sends request to server.
> 2) server answers
> the end.
> How to let the browser listen to the server?
>
> Short answer: You cannot. Not without some tricks or additional software
> (Java, Flash for example).
>
> Read up here first:
> http://en.wikipedia.org/wiki/Push_technology#HTTP_server_push
>
> You can see on that page that a few experiments have been tried, but
> none of them if fully reliable.
> For example: multipart/x-mixed-replace is not supported by IE, and I
> don't know about mobile devices.
>
> You have 2 options:
> 1) Make a client-pull approach, eg with XHR ("Ajax").
> http://en.wikipedia.org/wiki/XMLHttpRequest
> Advantage: Easy to implement.
> Drawback: All the connected clients will be sending update-requests all
> the time. This will lead to extra serverload which can kill the server
> if you have many clients trying to chat.
>
> 2) Use additional software that CAN listen.
> Problem: See former thread: Suppose your server wants to PUSH new data
> to some client: How to deliver that behind a firewall/NAT? To which port?
>
> Maybe IP6 and UPNP can help you out? I am not sure to be honest.
> http://en.wikipedia.org/wiki/UPNP
> UPNP can help you out of the NAT mess, but it isn't supported everywhere
> (I disabled it because I don't want programs to open ports on my router.)
>
> I once created a chat application, and resorted to PULL technology
> because of all the problems. In my situation that was OK because the
> load was low, and the approach worked (This was before the XHR days, and
> I used a hidden frame and Javascript to pull the trick.)
>
> Bottomline: Decide if you want to go CLIENT-PULL (easy, but limited) or
> SERVER-PUSH (Hard).
>
> But you better go to a networking group instead of this one.
> These advanced networking protocols (both IP6 and UPNP) are quite
> complex, and this isn't PHP related.

Or you can wait until websockets is more widely available - see RFC 6455:

<http://tools.ietf.org/html/rfc6455>

--
Tim

"That excessive bail ought not to be required, nor excessive fines imposed,
nor cruel and unusual punishments inflicted" -- Bill of Rights 1689

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[Message index]

		chat on web, Ajax ? By: SL on Fri, 24 February 2012 13:59
		Re: chat on web, Ajax ? By: SL on Fri, 24 February 2012 14:15
		Re: chat on web, Ajax ? By: Captain Paralytic on Fri, 24 February 2012 14:20
		Re: chat on web, Ajax ? By: SL on Fri, 24 February 2012 15:52
		Re: chat on web, Ajax ? By: The Natural Philosoph on Fri, 24 February 2012 15:59
		Re: chat on web, Ajax ? By: SL on Fri, 24 February 2012 16:23
		Re: chat on web, Ajax ? By: Doug Miller on Fri, 24 February 2012 16:52
		Re: chat on web, Ajax ? By: SL on Sat, 25 February 2012 02:01
		Re: chat on web, Ajax ? By: M. Strobel on Fri, 24 February 2012 15:22
		Re: chat on web, Ajax ? By: Erwin Moller on Fri, 24 February 2012 14:28
		Re: chat on web, Ajax ? By: Tim Streater on Fri, 24 February 2012 14:51
		Re: chat on web, Ajax ? By: The Natural Philosoph on Fri, 24 February 2012 15:54
		Re: chat on web, Ajax ? By: Tim Streater on Fri, 24 February 2012 19:02
		Re: chat on web, Ajax ? By: The Natural Philosoph on Fri, 24 February 2012 21:06
		Re: chat on web, Ajax ? By: Tim Streater on Fri, 24 February 2012 21:38
		Re: chat on web, Ajax ? By: The Natural Philosoph on Fri, 24 February 2012 21:51
		Re: chat on web, Ajax ? By: Tim Streater on Fri, 24 February 2012 22:26
		Re: chat on web, Ajax ? By: The Natural Philosoph on Sat, 25 February 2012 13:15
		Re: chat on web, Ajax ? By: Tim Streater on Sat, 25 February 2012 13:20
		Re: chat on web, Ajax ? By: The Natural Philosoph on Sat, 25 February 2012 13:33
		Re: chat on web, Ajax ? By: Tim Streater on Sat, 25 February 2012 13:42
		Re: chat on web, Ajax ? By: SL on Fri, 24 February 2012 16:31
		Re: chat on web, Ajax ? By: The Natural Philosoph on Fri, 24 February 2012 15:48
		Re: chat on web, Ajax ? By: Thomas 'PointedEars' on Fri, 24 February 2012 16:27
		Re: chat on web, Ajax ? By: Jeff North on Sat, 25 February 2012 13:13
		Re: chat on web, Ajax ? By: Arno Welzel on Sun, 26 February 2012 03:54

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