Test Scenerio


Tools usage for the Test

ASP.NET Web Application
..Net Framework 1.1
Windows XP
LocalHost
Fiddler HTTP Debugger
Internet Explorer


The web project also contains few JS files and Images. The application when
run through the

Internet Explorer, on local host, was not downloading few of the images and
js files on the

first case and secondly, few files were being downloaded on a subsequent
request ( here i

mean referred by other pages).

The tests were conducted first time by clearing the IE Cache (tempry folder)
and next just

refreshing IE. When looked through the Fiddler, i found :


Issue 1. (IE's cache is cleared)

Rarely and randomly few of the files are returned by server as bad
request(202). When the

same file is requested through Fiddler, the files are served properly (200).
The Headers

were proper.
On repeat request of the same application url in browser, the error may
occur again

(randomly)
with completely different file(s) (i.e the 500 error - Bad Response).

Y does this happen? Could it be because each resource request to the server
is created on

the
seperate "thread" and hence IIS is swamped with "requests" and returns a 202
for some?


Issue 2. (IE is simply refreshed - using F5)

Most of the files' response contained 304, Not Modified - which is correct
since the

If-Modified-Since
in the request header is = the Last-Modified on the file itself.

Few files which are downloading (we are facing an issue with some .js file(1
or 2) while

most other are correctly returning the 304 response ). For the ones where is
does not

return a 304 response, but instead a 200 - i.e its downloading the resource
form the IIS -

we noted that strangely the request header does not contain an
"If-Modified-Since" while

other resources with the same extension (i.e for example .js) do contain the

"If-Modified-Since" are we are correctly getting a 304 for them. How is the
client browser

(IE 6.0) seletively not sending the "If-Modified-Since" header for these (2
or 3) files

while doing it for the others? Any ideas? Anything to do with the physical
file attributes

in the application folder?


Any details on the above issues will be greatly appreciated.

Hello,

For issue 1, it may happen when the server or IIS thread is busy. For issue
2, Is it repeatable? I mean, does it always failed with same file?

Luke

[quoted text, click to view]
[...]

202 is not an error. It's just an information that a server received a
valid request. Here's what the spec says:

The request has been accepted for processing, but the processing has
not been completed. The request might or might not eventually be acted
upon, as it might be disallowed when processing actually takes place.
There is no facility for re-sending a status code from an asynchronous
operation such as this.

The 202 response is intentionally non-committal. Its purpose is to
allow a server to accept a request for some other process (perhaps a
batch-oriented process that is only run once per day) without requiring
that the user agent's connection to the server persist until the
process is completed. The entity returned with this response SHOULD
include an indication of the request's current status and either a
pointer to a status monitor or some estimate of when the user can
expect the request to be fulfilled.

This of course can also be used to gracefully tell a client that a
server is rather busy ;-)


[quoted text, click to view]

A conditional GET, which may lead to either a reload (200) or a not
(304), requires a local copy to make sense. Any non-cached file doesn't
really require a If-Modified-Since header -- the server *must* serve a
fresh copy every time.

Cheers,
--
http://www.joergjooss.de