Re: Continuations

["Marco Baringer" <address@hidden>]

"Perry E. Metzger" <perry@piermont.com> writes:

> Eli Collins <eli@cs.wisc.edu> writes:
>> Can a user's session be migrated to another machine if the server they are
>> talking to fails?
>> 
>> It seems this scheme would not be as strong at load balancing since a
>> user's request is always routed to a specific server regardless of how
>> loaded that server is.
>
> Provided no individual user is too much of a load, it shouldn't be a
> problem in practice. The real problem is assuring that an individual
> user always goes to a particular server in a given login session...

in my experience and biased opinion:

mapping parts of the session key space to particular servers is "good
enough", and (via mod_rewrite) very easy. while this means nothing for
fault tolerance for most people the loss of the server is far more
costly than the loss of the current sessions.

question: how many sites are actually run by more than one "business
logic" machine? (1 for apache (or whatever) + 1 for the db + 1 for the
logic makes three machines and can handle almost every site i've had
the pleasure to work with). i'm the first to admit i've only worked on
relativly low load apps, but aren't 95% of the web apps out there "low
load"?

-- 
Marco Baringer

Baringer Electronics and Software Engineering
www.bese.it