[Chameleon] IE red cross problem

Wed Jul 13 02:54:24 EDT 2005

Hmm.... ok, in that case I'm wrong :)

The problem is not likely to be in the chameleon code, because each image has a valid url, that leads to a valid image (eventually). Do you keep a log of every request sent to the web-server, including failed requests? Wonder what it says when an image breaks. Could it be that when many requests are sent at once, that the php memory limit is exceeded? (memory_limit in php.ini file)

I can not imagine that the requests are sent too quickly for a web-server to handle, because most web-servers have higher loads than that. Which would leave the option of a bug in IE....... 

My current version of IE (6.0.2800.1106.xpsp2) on winxp refuses to show broken images, no matter what. But my colleagues computer (win2k) does have it (6.0.2800.1106CO). I have seen it in win98, IE5.0 as well.

Jacob

-----Original Message-----
From: Bart van den Eijnden [mailto:BEN at Syncera-ITSolutions.NL] 
Sent: 13 July 2005 14:23
To: chameleon at lists.maptools.org; jacob.delfos at maunsell.com
Subject: RE: [Chameleon] IE red cross problem

Hi Jacob,

my site is running on Windows 2003 with IIS6 and it still occurs quite (frequently) there .....

Best regards,
Bart

Bart van den Eijnden
Syncera IT Solutions
Postbus 270
2600 AG  DELFT

tel.nr.: 015-7512436
email: BEN at Syncera-ITSolutions.nl

>>> "Jacob Delfos" <jacob.delfos at maunsell.com> 07/13/05 02:29am >>>
Well, I have to say it's a less frequent problem, but maybe I just haven't noticed as much because I use firefox most of the time. I noticed it only occurs with the combination of internet explorer (not all versions of it though) and Apache. My current version of IE doesn't suffer from it at all. I *think* it also improved since we switched from win2k to windows 2003 server. The essense of the problem is probably requests being fired too quickly, which would explain why win2k3 would deal with it better.

In version 1, the workaround I used made use of the 'onError' attribute of the map image (MapLayerDivImg), which in version 2 sits in MapDHTML.js. This function invoked a function when the image broke, which loaded an empty pixel into the map-image immediately (so users doesn't see red cross), and then (after 0.2 seconds) reloaded the correct URL back into the map image. The users does not notice if anything goes wrong. Legend images and scalebar can still break, though.

I haven't yet had a reason to implement this in version 2. Should be easy to do, so let me know if you want me to post the code, but you could probably figure it out yourself quite easily. You are right, in that it can cause an infinite loop. But only if the configuration of the site is wrong (e.g. error in mapfile). It would not loop if the site normally functions. And I think version 2 has better error-catching (e.g. error message in map image), which would prevent that from happening. It's not a clean solution, but a whole lot more comfortable than the user seeing broken images.

regards,

Jacob

-----Original Message-----
From: chameleon-bounces at lists.maptools.org [mailto:chameleon-bounces at lists.maptools.org] On Behalf Of Paul Spencer
Sent: 12 July 2005 20:17
To: Bart van den Eijnden
Cc: chameleon at lists.maptools.org 
Subject: Re: [Chameleon] IE red cross problem

Bart,

sorry but I have never seen this problem :( which makes it difficult to 
troubleshoot.  But I think Jacob did have the same problem.  I wonder if 
he found a solution.

Cheers

Paul

Bart van den Eijnden wrote:
> Hi list,
> 
> in my previous job when working with Chameleon I encountered the same problem, and now I am building a new product based on Chameleon a similar problem has arisen.
> 
> When loading the map in IE, sometimes a red cross appears. I have not been able to reproduce this in Firefox at all. It must have something to do with the image loading. Although I have never seen it happen to scalebar or reference map which are also generated by drawmap.php.
> 
> There were some threads about this in the past, one of them had as a work-around to add an OnError event to the map image, but this has a disadvantage that it can get into an endless loop.
> 
> Are there any new ideas or solutions on this? Are other people still experiencing this behaviour?
> 
> Best regards,
> Bart
> 
> Bart van den Eijnden
> Syncera IT Solutions
> Postbus 270
> 2600 AG  DELFT
> 
> tel.nr.: 015-7512436
> email: BEN at Syncera-ITSolutions.nl 
> 
> 
> _______________________________________________
> Chameleon mailing list
> Chameleon at lists.maptools.org 
> http://lists.maptools.org/mailman/listinfo/chameleon 
> 

-- 
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|Paul Spencer                           pspencer at dmsolutions.ca   |
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|Applications & Software Development                              |
|DM Solutions Group Inc                 http://www.dmsolutions.ca/| 
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