slow images and IE on asp.net site

[sviau]

any settings i need to set so that IE and other browsers cache the images
properly, especially during a preload.
it seems that using IE, the images are being requested each time when
refresh instead of accessing in browser cache

do we have to set the cache-control: public in asp.net page; currently its
set to cache-controlrivate

our images are not stored on the web servers but on dedicated image servers
http://pictures.mls.ca/mls/reb14/highres/1/1657611.jpg

this is our site with slow listing photo images:
http://www.mls.ca/PropertyDetails.aspx?PropertyID=2196284

i hear that there is a bug with IE; is this true?
http://www.netmechanic.com/news/vol6/javascript_no1.htm

thanks
stephane

 

[Steven Cheng[MSFT]]

Hi sviau,


Thanks for posting in the community!
From your description, you found that the Images on your web page seems
always downloaded from the remote url address rather than retrieved from
local browser cache, yes?
If there is anything I misunderstood, please feel free to let me know.

I've visited the link you provided and visit it via both IE and Mozilla and
did found that when I refresh the page, IE did cause more time to display
the images again, seems not using the cached image. In fact, the page use
the resource in cache first is default behavior so there is not additional
setting we need to do for the page or on serverside(such as in ASP.NET
code or ..). And we can find that those images did be downloaded into the
local Internet Temp folder of the IE Browser. I've searched for some
reference on the image cache in IE and found that there did exist some
issues when IE retrieve images in web page. Here are some the web links to
them:

#Internet Explorer May Not Use Images Stored in Local Cache
http://support.microsoft.com/default.aspx?scid=kb;en-us;217196

#Web Pages Retrieved Using Form Submit Are Not Retrieved from the Cache
http://support.microsoft.com/default.aspx?scid=kb;en-us;226972

So I think this maybe a internal behavior of the IE rather than caused by
any wrong setting of the web page or... Do you think so?



Regards,

Steven Cheng
Microsoft Online Support

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[Stephane Viau]

thank you for the resopurces, but they refer to old version of IE; does
it still impact IE 5+; in particular IE6?

does the fact that the page header has cache-control: private have
anything to do with it ?

thanks
stephane

 

[Eric Lawrence [MSFT]]

Here are the headers from your site:

GET /mls/reb14/highres/1/1657611.jpg HTTP/1.1
Accept: */*
Accept-Language: en-us
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR
1.1.4322; .NET CLR 1.0.3705)
Host: pictures.mls.ca
Proxy-Connection: Keep-Alive

HTTP/1.1 200 OK
Content-length: 15138
Date: Fri, 20 Feb 2004 09:29:07 GMT
Content-type: image/jpeg
Server: thttpd/2.20b 10oct00
Last-modified: Tue


This isn't anything you can control on your ASP.NET application-- you need
to fix the headers on your image delivery servers. For instance, you should
set a EXPIRES or Cache-control: max-age header. Generally, you do this
using the Web server software to assign a Content-expiration value for the
entire folder.

I could tell you how to do this in IIS, but I'm not sure how to do it in
thttpd. You'll have to check the docs.

--
Thanks,

Eric Lawrence
Program Manager
Assistance and Worldwide Services

This posting is provided "AS IS" with no warranties, and confers no rights.