tomcat-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Keith Bottner" <kbott...@comcast.net>
Subject RE: How do you set cache-control for static (gif, jpg) resources
Date Fri, 30 Jul 2004 15:09:53 GMT
Actually I never got any IllegalStateExceptions. When I get some more time I
will have to step through the Tomcat code and find out why I get called
twice since I should only be getting called once.

BTW, the 2.4 Servlet spec supports your analysis. It says the steps are
(specifically step4-5):


Step 1: The method examines the request's headers.

Step 2: The method may wrap the request object with a customized
implementation of ServletRequest or HttpServletRequest in order to
modify request headers or data.

Step 3: The method may wrap the response object passed in to its doFilter
method with a customized implementation of ServletResponse or
HttpServletResponse to modify response headers or data.

Step 4: The filter may invoke the next entity in the filter chain. The next
entity may be another filter, or if the filter making the invocation is the
last
filter configured in the deployment descriptor for this chain, the next
entity
is the target Web resource. The invocation of the next entity is effected by
calling the doFilter method on the FilterChain object, and passing in the
request and response with which it was called or passing in wrapped
versions it may have created.

The filter chain's implementation of the doFilter method, provided by the
container, must locate the next entity in the filter chain and invoke its
doFilter method, passing in the appropriate request and response objects.
Alternatively, the filter chain can block the request by not making the call
to
invoke the next entity, leaving the filter responsible for filling out the
response
object.

Step 5: After invocation of the next filter in the chain, the filter may
examine response headers.

Step 6: Alternatively, the filter may have thrown an exception to indicate
an error in processing. If the filter throws an UnavailableException during
its doFilter processing, the container must not attempt continued
processing down the filter chain. It may choose to retry the whole chain at
a later time if the exception is not marked permanent.

Step 7: When the last filter in the chain has been invoked, the next entity
accessed is the target servlet or resource at the end of the chain.

Step 8: Before a filter instance can be removed from service by the
container, the container must first call the destroy method on the filter to
enable the filter to release any resources and perform other cleanup
operations.


Thanks for all you help, I appreciate your time.

Keith
-----Original Message-----
From: Shapira, Yoav [mailto:Yoav.Shapira@mpi.com] 
Sent: Friday, July 30, 2004 9:55 AM
To: Tomcat Users List
Subject: RE: How do you set cache-control for static (gif, jpg) resources



Hi,
Yeah, I saw his response, but you didn't mention IllegalStateExceptions in
your log so I assumed the response being committed wasn't the problem
;)  Weird.

Yoav Shapira
Millennium Research Informatics


>-----Original Message-----
>From: Keith Bottner [mailto:kbottner@comcast.net]
>Sent: Friday, July 30, 2004 10:45 AM
>To: 'Tomcat Users List'
>Subject: RE: How do you set cache-control for static (gif, jpg)
resources
>
>RequestDumperValve dump's the request and the response.
>
>So the request is first and the response follows the double dash line
for
>that request.
>
>Tim Funk though pointed out the problem.
>
>"You probably can't set headers after doChain() because the response
was
>committed."
>
>See his entire message for more details. For now my filter works, I
will
>just have to use setHeader instead of addHeader and be happy with it
being
>called twice.
>
>Keith
>
>-----Original Message-----
>From: Shapira, Yoav [mailto:Yoav.Shapira@mpi.com]
>Sent: Friday, July 30, 2004 9:28 AM
>To: Tomcat Users List
>Subject: RE: How do you set cache-control for static (gif, jpg)
resources
>
>
>
>Hola,
>How's the RequestDumperValve useful, if what you want to inspect are
the
>response headers?  Unless you're sending the response to another Tomcat 
>server and this is the RequestDumperValve's log from that second
server?
>
>Yoav Shapira
>Millennium Research Informatics
>
>
>>-----Original Message-----
>>From: Keith Bottner [mailto:kbottner@comcast.net]
>>Sent: Friday, July 30, 2004 9:59 AM
>>To: 'Tomcat Users List'
>>Subject: RE: How do you set cache-control for static (gif, jpg)
>resources
>>
>>
>>
>>Unfortunately HttpServletResponse has now way to query the headers
only
>to
>>set them and determine if they exist. However I have the
>RequestDumperValve
>>for both editions of the code. Here is the log for the 1st set of code 
>>(your suggestions).
>>
>>
>>: ---------------------------------------------------------------
>>:           authType=BASIC
>>:      contentLength=659
>>:        contentType=image/gif
>>:             header=Pragma=No-cache
>>:             header=Cache-Control=no-cache
>>:             header=Expires=Wed, 31 Dec 1969 18:00:00 CST
>>:             header=ETag=W/"659-1091194009140"
>>:             header=Last-Modified=Fri, 30 Jul 2004 13:26:49 GMT
>>:            message=null
>>:         remoteUser=username
>>:             status=200
>>:             scheme=http
>>:         serverName=localhost
>>:         serverPort=8080
>>:        servletPath=/common/inject/emp-ui-bg-con-tl.gif
>>:           isSecure=false
>>: ---------------------------------------------------------------
>>: ---------------------------------------------------------------
>>:           authType=BASIC
>>:      contentLength=7675
>>:        contentType=image/gif
>>:             header=Pragma=No-cache
>>:             header=Cache-Control=no-cache
>>:             header=Expires=Wed, 31 Dec 1969 18:00:00 CST
>>:             header=ETag=W/"7675-1091194009140"
>>:             header=Last-Modified=Fri, 30 Jul 2004 13:26:49 GMT
>>:            message=null
>>:         remoteUser=username
>>:             status=200
>>
>>Above you can see that none of my changes to the response stream were
>used.
>>
>>
>>Here is the headers for the 2nd set of code (the original)
>>
>>: ---------------------------------------------------------------
>>: REQUEST URI       =/common/inject/emp-ui-bg-con-tl.gif
>>:           authType=BASIC
>>:  characterEncoding=null
>>:      contentLength=-1
>>:        contentType=null
>>:        contextPath=
>>:             cookie=JSESSIONIDSSO=47372C3C7BB03505C936A20970ACB1F9
>>:             cookie=JSESSIONID=B75E4FA2AA8047CCD40A885A0A84DFB5
>>:             header=accept=*/*
>>:             header=accept-language=en-us
>>:             header=accept-encoding=gzip, deflate
>>:             header=user-agent=Mozilla/4.0 (compatible; MSIE 6.0;
>Windows
>>NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322)
>>:             header=host=localhost:8080
>>:             header=connection=Keep-Alive
>>:             header=authorization=Basic ZGhhbHBpbjpkaGFscGlu
>>:             locale=en_US
>>:             method=GET
>>:           pathInfo=null
>>:           protocol=HTTP/1.1
>>:        queryString=null
>>:         remoteAddr=127.0.0.1
>>:         remoteHost=127.0.0.1
>>:         remoteUser=username
>>: requestedSessionId=B75E4FA2AA8047CCD40A885A0A84DFB5
>>:             scheme=http
>>:         serverName=localhost
>>:         serverPort=8080
>>:        servletPath=/common/inject/emp-ui-bg-con-tl.gif
>>:           isSecure=false
>>: ---------------------------------------------------------------
>>: ---------------------------------------------------------------
>>:           authType=BASIC
>>:      contentLength=7675
>>:        contentType=image/gif
>>:             header=Pragma=No-cache
>>:             header=Cache-Control=no-cache
>>:             header=Cache-Control=max-age=1800
>>:             header=Expires=Wed, 31 Dec 1969 18:00:00 CST
>>:             header=Cache-Control=no-cache
>>:             header=Cache-Control=max-age=1800
>>:             header=ETag=W/"7675-1091159753343"
>>:             header=Last-Modified=Fri, 30 Jul 2004 03:55:53 GMT
>>:            message=null
>>:         remoteUser=username
>>:             status=200
>>
>>
>>Do you see the duplicate Cache-Control above? The first 
>>Cache-control=no-cache is the default then my addition then another
>filter
>>adds the Expires and then both of the cache control lines are added
>again.
>>
>>Thanks for the performance tip, now if I can just get this!
>>
>>I appreciate any help you can offer.
>>
>>Keith
>>
>>-----Original Message-----
>>
>>From: Shapira, Yoav [mailto:Yoav.Shapira@mpi.com]
>>Sent: Friday, July 30, 2004 8:40 AM
>>To: Tomcat Users List
>>Subject: RE: How do you set cache-control for static (gif, jpg)
>resources
>>
>>
>>
>>Hi,
>>
>>>Previously I was calling doChain at the end of my doFilter method.
>>>
>>>Making the change you suggest, calling doChain at the top like
>><snip />
>>>DOES NOT INSERT any of my changes into the response stream. If I do
it
>>like
>>>this:
>><snip />
>>>Then I get two additions in the response stream.
>>>
>>>Any more ideas?
>>
>>That's a bit strange.  Are you wrapping the response or setting these 
>>headers elsewhere?  Can you print out to the log a listing of all the 
>>response headers at the end of your filter?
>>
>>The addHeader method allows for multiple values, but many readers will
>only
>>see the first.  So if something in your code sets the cache-control
>header,
>>then you call it again, the header will be present twice with two
>values
>>(which is legal in the HTTP protocol for most headers).
>>
>>As an aside, you can read the enumeration of the init parameters in
the
>>filter's init method, store it in some member variable, and that will 
>>improve the performance of your filter because you won't have to do it
>on
>>every request.
>>
>>Yoav Shapira
>>
>>
>>
>>This e-mail, including any attachments, is a confidential business 
>>communication, and may contain information that is confidential, 
>>proprietary and/or privileged.  This e-mail is intended only for the
>>individual(s)
>to
>>whom it is addressed, and may not be saved, copied, printed, disclosed
>or
>>used by anyone else.  If you are not the(an) intended recipient,
please
>>immediately delete this e-mail from your computer system and notify
the
>>sender.  Thank you.
>>
>>
>>---------------------------------------------------------------------
>>To unsubscribe, e-mail: tomcat-user-unsubscribe@jakarta.apache.org
>>For additional commands, e-mail: tomcat-user-help@jakarta.apache.org
>>
>>
>>---------------------------------------------------------------------
>>To unsubscribe, e-mail: tomcat-user-unsubscribe@jakarta.apache.org
>>For additional commands, e-mail: tomcat-user-help@jakarta.apache.org
>
>
>
>
>This e-mail, including any attachments, is a confidential business 
>communication, and may contain information that is confidential, 
>proprietary and/or privileged.  This e-mail is intended only for the 
>individual(s)
to
>whom it is addressed, and may not be saved, copied, printed, disclosed
or
>used by anyone else.  If you are not the(an) intended recipient, please 
>immediately delete this e-mail from your computer system and notify the 
>sender.  Thank you.
>
>
>---------------------------------------------------------------------
>To unsubscribe, e-mail: tomcat-user-unsubscribe@jakarta.apache.org
>For additional commands, e-mail: tomcat-user-help@jakarta.apache.org
>
>
>---------------------------------------------------------------------
>To unsubscribe, e-mail: tomcat-user-unsubscribe@jakarta.apache.org
>For additional commands, e-mail: tomcat-user-help@jakarta.apache.org




This e-mail, including any attachments, is a confidential business
communication, and may contain information that is confidential, proprietary
and/or privileged.  This e-mail is intended only for the individual(s) to
whom it is addressed, and may not be saved, copied, printed, disclosed or
used by anyone else.  If you are not the(an) intended recipient, please
immediately delete this e-mail from your computer system and notify the
sender.  Thank you.


---------------------------------------------------------------------
To unsubscribe, e-mail: tomcat-user-unsubscribe@jakarta.apache.org
For additional commands, e-mail: tomcat-user-help@jakarta.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: tomcat-user-unsubscribe@jakarta.apache.org
For additional commands, e-mail: tomcat-user-help@jakarta.apache.org


Mime
View raw message