remmers
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An Exercise in URL Rewriting
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Mar 8 17:49 UTC 2007 |
The mod_rewrite module of the Apache webserver can be used to translate
a requested URL to a different one. This is useful for example if a
page has been moved to a new location, but you still want the old URL to
work.
If the webserver has been configured to allow it, this facility is
available to users on a per-directory basis. You create a file
named .htaccess in the directory in which you want URL translations to
apply and put some directives in the file that specify how the
translation should be done.
As an exercise for myself in writing .htaccess files, I've implemented a
simplified URL scheme for read-only access to Grex conferences, items,
and responses. It works as follows:
http://jremmers.org/grex/bbs -list of all conferences
http://jremmers.org/grex/bbs/CONF -index of conference CONF
http://jremmers.org/grex/bbs/CONF/ITEM -content of an item
http://jremmers.org/grex/bbs/CONF/ITEM/SEL -selected part of an item
Examples:
http://jremmers.org/grex/bbs/kitchen -index of kitchen cf.
http://jremmers.org/grex/bbs/web/5 -item 5 of web cf.
http://jremmers.org/grex/bbs/web/5/2 -resp 2 of item 5 of web cf.
http://jremmers.org/grex/bbs/web/5/1-4 -resps 1-4 of that item
Note that even though the domain given in the URLs is my website, no
Grex conference content is actually stored there.
Feel free to play around with this. I'll explain how I did it in a
subsequent response.
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remmers
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response 3 of 11:
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Mar 9 21:59 UTC 2007 |
I did some reading up on and experimentation with the HTTP referer
header. Typically it's sent by a browser when you follow a link; its
value is the URL of the page on which the link occurs. It's a reverse
link from the target of the original link back to the source.
If you're reading this in Backtalk, you can see the value of the referer
header by clicking on this link: http://c2.com/cgi/test/
You'll get a display of the list of HTTP headers that your browser sent
to the server at c2.com. Unless your browser is configured not to send
referer headers, one of the headers will be HTTP_REFERER; its value is
the URL of the Backtalk page on which the link occurs.
On the other hand, if you go to a URL by simply typing it into your
browser address window, your browser shouldn't send a referer header.
You can try this out with c2.com too.
I think all that is completely independent of any rewriting that
mod_rewrite does, though, since the referer header is sent by the
browser before any rewriting on the server takes place.
(My starting point for the above was looking at the "HTTP referer"
article in Wikipedia (http://en.wikipedia.org/wiki/HTTP_Referer). The
article points out that the correct spelling is "referrer" and that
whoever made up the HTTP header name misspelled it.)
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