Hi all,

 

Found the solution to this and wanted to share that with you ;-)

 

Everytime a new read was done on the layer through refreshing the
refresh event triggered the update of the BBOX strategy. Here the abort
was called on the protocol.

In the protocol abort method the abort was propagated to the
XMLHttpRequest.

The abort method of the XMLHttpRequest propagated again to the
XMLHttpRequest native object or the ActiveX object depending on the
browser used.

It seems that the abort is not working correctly if readystate has
reached 4 already. So changing that to conditionally propagate the abort
only when readystate > 0 and < 4 did the trick.

 

Attached you'll find a patch file including this change and also:

-          Setting readystatechange function after open is called (as
good practice from ajaxian.com:
http://ajaxian.com/archives/reusing-xmlhttprequest-without-abort)

-          Applied changes from version 1.0.3 of the used library from 
http://code.google.com/p/xmlhttprequest

 

Hope its usefull for anyone (and makes it into a new release).

 

Cheers Kris

 

From: Kris Geusebroek 
Sent: Monday, April 27, 2009 9:52 AM
To: Kris Geusebroek; [email protected]
Subject: RE: [OpenLayers-Users] Error when using XMLHTTPRequest
(throughrefreshing a wfs layer every n seconds)

 

Hi All,

 

Some further investigating shows that the location of the error
(unspecified error) is at line 1087 /29937 (for uncompressed
openLayers.js)

This is the line in XMLHTTPRequest.js where the this._object.send(vData)
is called form cXMLHttpRequest.prototype.send

 

In script debugeer I can see that this._aborted = true

But nothing more strange things to see.

 

Anybode knows how I can investigate more?

 

Cheers Kris

 

From: [email protected] [mailto:[email protected]]
On Behalf Of Kris Geusebroek
Sent: Monday, April 27, 2009 8:17 AM
To: [email protected]
Subject: [OpenLayers-Users] Error when using XMLHTTPRequest
(throughrefreshing a wfs layer every n seconds)

 

Hi all,

 

When using openlayers to refresh my wfs layers frequently after some
time using the application (zooming, panning etc while still refreshing
every n seconds)

I get an error: unknown error at line 977 (or 1076 sometimes).

After that error the app becomes very unresponsive. Zooming in for
example takes about 30 seconds after clicking the button in the PanZoom
control.

 

My feeling is that the error comes form the XMLHttpRequest code so I
need to investigate that more.

Anybody know a good help to investigate what goes wrong and to find out
how to fix this?

 

Environment is IE6 (I know bad choice). But the error also comes in
Firefox but there the response times remain ok.

 

Any help I much appreciated

 

Cheers

 

Kris Geusebroek

Consultant

 

 

Email: [email protected] <mailto:[email protected]> 

Tel: +31 (0)35 538 1921

Fax: +31 (0)35 538 1922

Mobile: +31 (0)6 30 697 223

http://www.xebia.com <http://www.xebia.fr/> 

 

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1213 TL Hilversum

The Netherlands 

 

Xebia Blog !   http://blog.xebia.com/ <http://blog.xebia.com/>    

Xebia Podcast!   http://podcast.xebia.com/ <http://podcast.xebia.com/>  

 

<<image001.jpg>>

Attachment: xmlhttprequest.patch
Description: xmlhttprequest.patch

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