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From "William A. Rowe, Jr." <>
Subject Re: mod_proxy / mod_proxy_balancer
Date Wed, 06 May 2009 17:00:32 GMT
Jim Jagielski wrote:
> That's why oob-like health-and-status chatter is nice, because
> it doesn't interfere with the normal reverse-proxy/host logic.

+1, for a backend of unknown status (let's just say it's a few minutes
old, effectively useless information now) ping/pong is the right first
approach.  But...

> An idea: Instead of asking for this info before sending the
> request, what about the backend sending it as part of the response,
> as a response header. You don't know that status of the machine
> "now", but you do know the status of it right after it handled the last
> request (the last time you saw it) and, assuming nothing else touched
> it, that status is likely still "good".

Yup; that seems like the only sane approach, add an X-Backend-Status or
whatnot to report the load or other health data.  It's easily consumed
(erased) from the front end response.  If done correctly in a backend
server, it can convey information from the ultimate back end resources
that actually cause the congestion (DB servers or whatnot) rather than
the default response (CPU or whatnot) at the middle tier..

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