[coral-users] Re(2): About the 403 error

[Michael J. Freedman]

Hi Leo,

>From our discussions offline, it seems like as a GB/day kinda guy, you'd 
still much prefer Coral to redirect requests it "can't handle" back to 
your site.

There was a bunch of discussion on "Graceful failover" in the Feburary 
archives of this list:

   http://www.cs.nyu.edu/pipermail/coral-users/2005-February/

Basically, I've implemented failover, such that if you want Coral to 
always redirect back to your origin site when it can't handle it, you 
should:

1. Add a header line:

     X-Coral-Control: redirect-home

to requests when you respond to coral proxyies.  (Recall that you can 
differentiate Coral requests by checking User-Agent has CoralWebPrx.

If Coral redirects a client back to the origin site, it will append 
?coral-no-serve on the end of the URL, i.e.,

  http://www.example.com/foo --> http://www.example.com/foo?coral-no-serve

2. In case you use mod_rewrite to automatically redirect clients to 
Coralized URLs (of course, checking user-agent that client isn't a coral 
proxy itself trying to fetch the file), you need to add another check such 
that you don't redirect clients if "?coral-no-serve" exists.

Note that if you aren't using mod_rewrite or anything else dynamic, you 
don't need to worry about #2, because anything after "?" is effectively 
ignored by your webserver for static content.

I implemented this over the weekend, I've just been delayed while 
PlanetLab has some serious DNS problems and many nodes (50%) are 
inoperative. Thankfully, much of this problem has been hidden from clients 
due to Coral's redundancy.

--mike


On Thu, 3 Mar 2005, Leo Laporte wrote:

> Date: Thu, 3 Mar 2005 14:24:26 -0800
> From: Leo Laporte <leo at leoville.com>
> To: Coral Users <coral-users at cs.nyu.edu>
> Subject: [coral-users] Re(2):  About the 403 error
> 
> Speaking as a GB/day kinda guy, I'm having real problems with 403 errors
> and my podcasts.
>
> It's in the nature of podcasts that all the traffic clusters around the
> new cast release dates. I'm getting 403s due to condition 2 below every
> time I release a new podcast now and my users are not happy. Podcast
> clients don't handle the 403s very well apparently.
>
> I guess Coral and podcasting are not compatible? Or do you see a light at
> the end of this particular tunnel?
>
> Leo
>
> -- 
> Leo Laporte                           <http://leoville.com>
> KFI AM 640, Los Angeles                  Sat-Sun, 11a to 2p
> Call for Help on G4techTV Canada             Weekdays at 6p
> PO Box 1018, Petaluma, CA 94952   <mailto:leo at leoville.com>


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"Not all those who wander are lost"             www.michaelfreedman.org
"You make it fun; we'll make it run"                   www.coralcdn.org