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Posted to dev@httpd.apache.org by Amila Liyanaarachchi <am...@gmail.com> on 2011/10/06 19:03:10 UTC
Caching - Generating E-Tags
Hi Dev,
I'm working on a caching protocol similar to HTTP on a different research. I
have the following question regarding the e-tags.
When does exactly apache computes the e-tag for a certain resource?
Does it compute that when there is a request for that particular resource or
is it computed by the server whenever a resource get modified in the
server?
Thanks,
Amila
Re: Caching - Generating E-Tags
Posted by Igor Galić <i....@brainsware.org>.
----- Original Message -----
>
>
> Am 10.10.2011 00:10, schrieb Igor Galić:
> > ----- Original Message -----
> >> request time because it normally contains the inode
> >
> > Which makes it quite useless in a farm with multiple servers
> > as the same files will have different inodes.
> > My recomendation is to use size and mtime
>
> well, most setups are NOT a farm with multiple servers
In this age and time I wonder how long that statement
will hold true.
> so if you have not a default-setup change the defaults
>
> FileETag -INode
i
--
Igor Galić
Tel: +43 (0) 664 886 22 883
Mail: i.galic@brainsware.org
URL: http://brainsware.org/
GPG: 571B 8B8A FC97 266D BDA3 EF6F 43AD 80A4 5779 3257
Re: Caching - Generating E-Tags
Posted by Reindl Harald <h....@thelounge.net>.
Am 10.10.2011 00:10, schrieb Igor Galić:
> ----- Original Message -----
>> request time because it normally contains the inode
>
> Which makes it quite useless in a farm with multiple servers
> as the same files will have different inodes.
> My recomendation is to use size and mtime
well, most setups are NOT a farm with multiple servers
so if you have not a default-setup change the defaults
FileETag -INode
Re: Caching - Generating E-Tags
Posted by Igor Galić <i....@brainsware.org>.
----- Original Message -----
>
> Am 06.10.2011 19:03, schrieb Amila Liyanaarachchi:
> > Hi Dev,
> >
> > I'm working on a caching protocol similar to HTTP on a different
> > research. I have the following question regarding
> > the e-tags.
> > When does exactly apache computes the e-tag for a certain resource?
> > Does it compute that when there is a request for that particular
> > resource or is it computed by the server whenever
> > a resource get modified in the server?
>
> request time because it normally contains the inode
Which makes it quite useless in a farm with multiple servers
as the same files will have different inodes.
My recomendation is to use size and mtime:
http://httpd.apache.org/docs/current/mod/core.html#fileetag
ETag is then an MD5 sum of a combination of all values considered.
Be wary that the calculation of the ETag can sometimes take more
effort than just delivering the ETag.
See Theo Schlossnagle's performance talks for reference:
http://omniti.com/seeds/yslow-to-yfast-in-45-minutes
http://lethargy.org/~jesus/writes/web-performance-boot-camp
i
--
Igor Galić
Tel: +43 (0) 664 886 22 883
Mail: i.galic@brainsware.org
URL: http://brainsware.org/
GPG: 571B 8B8A FC97 266D BDA3 EF6F 43AD 80A4 5779 3257
Re: Caching - Generating E-Tags
Posted by Reindl Harald <h....@thelounge.net>.
Am 06.10.2011 19:03, schrieb Amila Liyanaarachchi:
> Hi Dev,
>
> I'm working on a caching protocol similar to HTTP on a different research. I have the following question regarding
> the e-tags.
> When does exactly apache computes the e-tag for a certain resource?
> Does it compute that when there is a request for that particular resource or is it computed by the server whenever
> a resource get modified in the server?
request time because it normally contains the inode
Re: Caching - Generating E-Tags
Posted by Stefan Fritsch <sf...@sfritsch.de>.
Hi,
On Thursday 06 October 2011, Amila Liyanaarachchi wrote:
> I'm working on a caching protocol similar to HTTP on a different
> research. I have the following question regarding the e-tags.
> When does exactly apache computes the e-tag for a certain resource?
> Does it compute that when there is a request for that particular
> resource or is it computed by the server whenever a resource get
> modified in the server?
If you don't need to be compatible to HTTP and don't want to make the
same errors, http://www2002.org/CDROM/refereed/444.pdf is a good
read.
Cheers,
Stefan