Comments on: Foldblog: Handling Multiple XHRs

By: Luis Torrefranca

Luis Torrefranca — Sat, 18 Feb 2006 18:48:06 +0000

I have a way to get around the single http_request resource and multiple requests to it. It still uses it as a global variable, but as an array. In a nutshell, it goes through the array and finds an available resource. If there isn’t one, it creates a new one.

Here’s a sample of it in use: http://www.digitalbonsai.com/xhrmulti.php

Three functions that use XHR are called at the same time (well, one right after the other). The list at the bottom of the page show the xhr[] variables that were generated.

- Luis (lu@digitalbonsai.com)

By: The Web Chronicals » Blog Archive » Foldblog: Handling Multiple XHRs

The Web Chronicals » Blog Archive » Foldblog: Handling Multiple XHRs — Thu, 26 Jan 2006 02:35:57 +0000

[...] Foldblog: Handling Multiple XHRs Apparently, Fold (not there yet) is to be a new Web 2.0 start page. In any event, the Fold Development Blog, by Axel Wolf, is explaining the goings-on in their Ruby-On-Rails development effort, and a recent post explains how they deal with multiple â€¦ [...]

By: mikepk

mikepk — Wed, 25 Jan 2006 21:44:05 +0000

so much for fancy formatting.
network.http.pipelining=false
network.http.pipelining.maxrequests=4
network.http.proxy.pipeline=false
Change the booleans to true, and increase the max request to some reasonable number like 20. Add a property â€œnglayout.initialpaint.delay=0â€³. Obviously this is a little involved for end users but could be useful for testing purposes.

By: mikepk

mikepk — Wed, 25 Jan 2006 21:39:47 +0000

So digging into the multiple request issue a bit, I think I’ve found that firefox can actually hold more request in flight simultaneously. Essentially you want to enable pipelining and increase the max outstanding values. Go into firefox, and go to “about:config”.
There are a few options you can tweak regarding simultaneity. Put “network.http” into the filter box. The options you’re looking for are the following.
network.http.pipelining=falsenetwork.http.pipelining.maxrequests=4network.http.proxy.pipelining=false

Change the booleans to true, and increase the max request to some reasonable number like 20. Add a property “nglayout.initialpaint.delay=0″. Obviously this is a little involved for end users but could be useful for testing purposes.

Check out YAJAF! still soliciting feedack!

By: Axel Wolf

Axel Wolf — Wed, 25 Jan 2006 19:34:17 +0000

Yeah, it should read that you have one “single, globally defined variable” (that is assigned a new XHR object for each call etc. which will ovioulsly not work if you have more than one request at a time) Thanks for pointing this out.

By: mikepk

mikepk — Wed, 25 Jan 2006 19:10:42 +0000

Hmm that’s interesting, I guess I never noticed since most of my sample applications use very small communication payloads between application and back end. Fired up the network analyzer, and sure enough it looks like you’re right. Gonna make a new sample application to pound on the data pipe interface to see what I can get on the network analyzer. Makes me think that maybe a scatter/gather method might work for increasing the efficiency of the link, especially for smaller transactions. Will try to implement and see what it does.
Thanks for the tip!

By: Christophe

Christophe — Wed, 25 Jan 2006 18:42:38 +0000

In firefox you can only have two pending requests. You can create an infinity of XHRs objects, but requests will only be dispatched two by two. I haven’t tested it in IE yet, but certainly it has something like that too. This is a good limitation, if you could create an infinity of pending requests this would overload the web server.

By: mikepk

mikepk — Wed, 25 Jan 2006 18:24:35 +0000

Actually you have to create a new XHR object for every request. I think he’s saying they have one function/object that wraps this creation process and handles the asynchrounous return.

In my own framework I use some neat object oriented techniques to handle multiple requests. I’m guessing it’s similar to the “ajax in action” referred to in the text.

I create “data pipe” objects and have objects that implement a pipe-reciever interface. Objects that use the data pipe, are automatically returned the data they requested through the interface.

Stll looking for feedback on YAJAF!, all comments welcome.

By: Julien Couvreur

Julien Couvreur — Wed, 25 Jan 2006 18:07:07 +0000

â€œMost introductory AJAX examples only have a single, globally defined XMLHttpRequest object. â€œ

I thought most tutorials actually show you to create a new XHR object for every request, which is the opposite problem.

By: La brujula verde » Fold, otra pÃ¡gina de inicio “Ã la web 2.0″

La brujula verde » Fold, otra pÃ¡gina de inicio “Ã la web 2.0″ — Wed, 25 Jan 2006 17:10:02 +0000

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