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From Stefan <stefan.rie...@telig.de>
Subject Re: Context attribute "cachingAllowed" does not work as expected. Is this a bug?
Date Mon, 12 Feb 2007 23:18:32 GMT
Caldarale, Charles R schrieb:
>> From: Stefan [mailto:stefan.riegel@telig.de] 
>> Subject: Context attribute "cachingAllowed" does not work as 
>> expected. Isthis a bug?
>>
>> That means once set to false, that tomcat will not cache any static
>> resources like the index.html page regardless which headers the client
>> sends. So tomcat should not send the status code 304.
>>     
>
> I'm not completely sure about this, but I think you're confusing server
> caching with client caching.  If the client requests content with a last
> modified timestamp, the server will check if the content has changed
> since then and either send the updated content with a 200 or just return
> the 304 and let the client use what it already has.  The cachingAllowed
> attribute of <Context> only controls whether or not Tomcat's
> DefaultServlet keeps a copy in Tomcat's memory of what it reads from the
> file system; it does not set the response headers to indicate to the
> client that the information should not be cached at the client end.  To
> do that, you'll need to use your own filter.
>
> You might want to use Ethereal or any of the browser header monitoring
> tools to look at the complete set of headers being used.
>
>  - Chuck
>
>
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>   
Hi Chuck,

yes it makes sense what You said. But something is very strange. First 
of all I tried a thousands of variations to set response headers in the 
filter. See here, for some variations, I tried all mentioned in this thread:
http://www.nabble.com/Cache-problems-with-static-resources-tf3031321.html#a8422512

I am completely confused. My Mozilla Plugin shows the following response 
header for the index.html. Obvious the 200 OK is wrong. tomcat returned 304.

Server: Apache-Coyote/1.1
Pragma: No-cache
Cache-Control: no-cache
Expires: Thu, 01 Jan 1970 01:00:00 GMT+01:00
Etag: W/"388-1169076375500"
Last-Modified: Wed, 17 Jan 2007 23:26:15 GMT
Content-Type: text/html
Content-Length: 388
Date: Mon, 12 Feb 2007 23:02:29 GMT
200 OK

and the corresponding request

user-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.1.1) 
Gecko/20061204 Firefox/2.0.0.1
accept: 
text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
accept-language: de,en;q=0.7,en-us;q=0.3
accept-encoding: gzip,deflate
accept-charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
keep-alive: 300
connection: keep-alive
cookie: JSESSIONID=05A42BA6580697E19E4DF8EC46288F49
if-modified-since: Thu, 01 Jan 1970 00:00:00 GMT
if-none-match: W/"1055-1171218303453"
authorization: Basic ZG9uOmVzdGViYW4=

by the way. Requesting a jsp always works but it is no option. See the 
index.jsp response

Server: Apache-Coyote/1.1
Pragma: No-cache
Cache-Control: no-cache
Expires: Thu, 01 Jan 1970 01:00:00 GMT+01:00
Content-Type: text/html;charset=ISO-8859-1
Content-Length: 238
Date: Mon, 12 Feb 2007 23:12:39 GMT
200 OK

I suspected the etag but setting the etag to blank (no way to delete 
headers, or is their a way?) does not help either.

-- 
Stefan


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