Re: Session's persistance?!?!?
Re: Session's persistance?!?!?
- Subject: Re: Session's persistance?!?!?
- From: David Neumann <email@hidden>
- Date: Thu, 3 Apr 2003 12:40:43 -0600
Stefano
Another idea is a hybrid approach. You leave WO alone in terms of
request handling (let it send requests to the instance that spawned the
session) but always archive the session anyway. This gives you good
performance in that there is no session to unarchive (it's in memory)
plus you avoid redundantly fetching non-common rows over and over as
you bounce among instances. But you still get an element of fail-over.
That is, if the instance dies, your custom restore-session methods can
recover an archived session if one can be found. Plus this recover
method can probably do a more efficient job of grabbing unfetched rows
for archived EOs... For example, you could fetch all 'Products' using
one query instead of multiple faulting queries.
The downside is that there will be a potential delay in returning the
session. If the instance dies and the user immediately hits the server
again, they will get a instance-not-available-warning or some such
equivalent from the WOAdaptor at least until the instance specified in
the URL restarts.
d
On Wednesday, April 2, 2003, at 08:33 PM, Chuck Hill wrote:
Posted a long time ago in a list far, far away...
Perhaps you will find his advice useful. Or terrifying.
Chuck
That is all I can remember for now..
Why not do it the easy way, and use WebObjects own loadbalancing
methods.. Buy a cheap linux box with apache and compile the
WebObjects adaptor.. Set up a few WO App servers.. Configure it (using
monitor) to load balance between them.. EASY !! Each request gets
routed back to the insance it came from.. The advantages are simple:
1. No overhead due to storing the session in the database.
2. You code is less likely to break, due to accidently archiving
something incorrectly
3. It takes 1 third the time to construct an app from scratch.
Disadvantage:
If a machine falls over, all the users on that machine loose their
session.. (but you code is more likely to explode if you do it the
other way..)
The other option is to get the load balancer to maintain a connection
to one server for their session (somehow)
DONT DO IT !
Regards,
Mark
Disclaimer: Don't know, don't care.. The code above is there ONLY as
a pointer, you must understand what it is doing and put in better
validation and the like.. Good luck..
Stefano Lesandrini wrote:
I will wondering if somebody could tell me it's possible
to have persistent sessions! In other words, I would like a session,
stopped due to a crash of the wo thread (or by a failure of the whole
application server) could be acquired (and mainteined) by another
application server. I'm referring to a three tiers
architecture (hw & sw) :
--> client: browser/java
--> RAIC of wo servers (apache+wo)
--> RDBMS server
The goal is to reach the highest achievable RAS.
Thank You very much for any suggestion.
/Steve
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--
Chuck Hill email@hidden
Global Village Consulting Inc.
http://www.global-village.net
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