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From "Douglas W. Goodall" <douglas_good...@mac.com>
Subject Re: [users@httpd] image display error with stock icon
Date Mon, 15 Feb 2016 04:04:28 GMT
Thanks for responding Chris.

The URL names are:

https://goodall.us.com/img/switch-up.jpg <https://goodall.us.com/img/switch-up.jpg>
https://goodall.us.com/img/switch-dn.jpg <https://goodall.us.com/img/switch-dn.jpg>

When I converted them to text strings for inclusion in the python source, it looked like the
first half of the 
image file is near identical.. I can spot differences down about half way by eye. I can understand
if the web
server digested the first 1k of the image they might seem identical. I guess a switch would
be the pathological
case because the outside would be identical, and somewhere inside the action would move one
way or 
another.

I used the demo mode in chrome and looked at the url of the img src, and while it said switch-up,
the tool-tip
image that came up was the down switch. Then I converted the image files to text for inclusion
in the 
python in case that would help and it did not.


Here are my simplified test files.

[root@cloud-goodall-us-com html]# cat images.py
#!/usr/bin/python 
# /var/www/html/images.py  2/13/2016 dwg -                 #
############################################################

SWITCHDN = "data:image/jpeg;base64,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"

SWITCHUP = "data:image/jpeg;base64,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"

#######
# eof #
#######



[root@cloud-goodall-us-com html]# cat state0.cgi
#!/usr/bin/python 
# /var/www/html/state0.cgi 2/13/2016 dwg -                 #
############################################################
import os
import sys
import sysconfig
import images

print("Content-type:    text/html\n\n")
import cgi,cgitb
cgitb.enable()
print("<!DOCTYPE html>\n")
print("<html>\n")
print("  <head>\n")
print("  </head>\n")
print("  <body>\n")
print("<a href=\"https://goodall.us.com/state1.cgi\"><img src=\""+images.SWITCHDN+"\"></a>")
print("  </body>\n")
print("</html>\n")


[root@cloud-goodall-us-com html]# cat state1.cgi
#!/usr/bin/python 
# /var/www/html/state0.cgi 2/13/2016 dwg -                 #
############################################################
import os
import sys
import sysconfig
import images

print("Content-type:    text/html\n\n")
import cgi,cgitb
cgitb.enable()
print("<!DOCTYPE html>\n")
print("<html>\n")
print("  <head>\n")
print("  </head>\n")
print("  <body>\n")
print("<a href=\"https://goodall.us.com/state0.cgi\"><img src=\""+images.SWITCHUP+"\"></a>")
print("  </body>\n")
print("</html>\n")






> On Feb 14, 2016, at 7:29 PM, Christopher Schultz <chris@christopherschultz.net>
wrote:
> 
> Douglas,
> 
> On 2/14/16 9:44 PM, Douglas W. Goodall wrote:
>> I have written a very simple pair of cgi scripts in python that display
>> a toggle switch either
>> in the up position, or in the down position. When you click on the
>> switch, it toggles between
>> the two and switches between the images appropriately. At least that is
>> what it is supposed
>> to do.
>> 
>> The problem presented itself as the switch always being in the down
>> position, no matter
>> how I toggled and switched between the cgi scripts.
>> 
>> Here is the down
>> and here is the up.
>> 
>> I checked in the browser debugger and the cgi scripts were trying to
>> send the proper images.
>> I tried the in the Mac OS X based Safari and Chrome and had identical
>> results.
>> 
>> When I eventually gave up and used different switch images, the problem
>> went away, so it
>> is my best guess that there is something pathological about the binary
>> contents of the images
>> making the Web Server send a cached version of the down switch image
>> instead of the up
>> switch image that is needed.
> 
> If the URL of the switch image the same in both cases (e.g.
> /images/switch_state.cgi)?
> 
> If so, you may be dealing with browser caching. Use the usual cadre of
> response headers to instruct the client not to cache the response.
> 
> If not, then the problem may still be a cached image, possibly from a
> time where the URL pointed to the wrong image.
> 
> Using Chrome's dev tools, you can see exactly what the client HTTP
> request and server HTTP response look like. That may help find out
> what's going on.
> 
> -chris
> 
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