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Date: Thu, 3 Sep 2009 08:52:39 +0530
Message-ID: <c71c91400909022022n5c20e1ebgf1d9deee969baf7f@mail.gmail.com>
Subject: Re: Apache Server failover and session replication
From: Sumedh Sakdeo <sumedhsakdeo@gmail.com>
To: Tomcat Users List <users@tomcat.apache.org>
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http://tomcat.apache.org/tomcat-6.0-doc/cluster-howto.html
*How it Works
*

   1. TomcatA starts up
   2. TomcatB starts up (Wait that TomcatA start is complete)
   3. TomcatA receives a request, a session S1 is created.
   4. TomcatA crashes
   5. TomcatB receives a request for session S1
   6. TomcatA starts up
   7. TomcatA receives a request, invalidate is called on the session (S1)
   8. TomcatB receives a request, for a new session (S2)
   9. TomcatA The session S2 expires due to inactivity.

section describes the steps.7-9 steps confusing.
Does tomcat 6 even support such scenario?

--Sumedh


On Thu, Sep 3, 2009 at 6:29 AM, Shaun Senecal <ssenecal.work@gmail.com>wrote:

> After re-reading your initial post, the problems might not be as related as
> I thought since at no point did replication "stop" for me.
>
>
> On Thu, Sep 3, 2009 at 9:56 AM, Shaun Senecal <ssenecal.work@gmail.com
> >wrote:
>
> > We had a similar problem with Tomcat 6 using clustering.  It turns out
> that
> > the SSO information is only propagated while all instances are running.
>  If
> > Instance-A fails, several users then log in to Instance-B, then
> Instance-A
> > comes back up, all of the SSO information for the users that logged in
> > during the downtime is not included in Instance-A so those users are
> forced
> > to re-login once the load balancer sends them to that instance.
> >
> > I wrote a fix for it, which might be useful for you.  However, it hasnt
> > been fully tested and is designed to only share the SSO information at
> > startup, not all Session information.  If Tomcat doenst handle this case,
> > then the fix I wrote should be easily extended to handle that.
>  Basically,
> > when an instance comes up it broadcasts a request for all known SSO
> > information to the cluster.  It then takes the first response it gets and
> > continues processing as normal.
> >
> > Let me know if you dont find a proper solution to the problem and I will
> > try to dig up that fix.  My intention was to post it back to the group,
> but
> > I got sidetracked once we (temporarily) stopped using clustering.
> >
> >
> > Shaun
> >
> >
> > On Thu, Sep 3, 2009 at 3:52 AM, Sumedh Sakdeo <sumedhsakdeo@gmail.com
> >wrote:
> >
> >> Hi Rainer,
> >>
> >> I am using Tomcat session clustering and Apache Http Server for LB(using
> >> mod_jk module).  Also, using Tomcat 6. I have made appropriate changes
> to
> >> worker.properties and httpd.conf. Also I have made appropriate changes
> to
> >> server.xml on each tomcat.
> >>
> >> Thanks,
> >> Sumedh
> >>
> >> On Thu, Sep 3, 2009 at 12:15 AM, Rainer Jung <rainer.jung@kippdata.de
> >> >wrote:
> >>
> >> > On 02.09.2009 19:57, Sumedh Sakdeo wrote:
> >> > > Hello All,
> >> > >             I have a setup with two tomcat instances(A&B). I have
> >> > configured
> >> > > an apache web server 2.2 for load balancing and fail over. Setup
> looks
> >> > fine
> >> > > as per the configurations suggested. Let tomcat A be handling some
> >> > request
> >> > > at sometime. When tomcat instance(A) goes down, the session is
> >> replicated
> >> > to
> >> > > another tomcat instance(B) successfully. Now tomcat instance B is
> >> > handling
> >> > > those requests. Till this point everything goes fine, but when I
> bring
> >> up
> >> > > tomcat instance(A) and after that tomcat instance(B) goes down, the
> >> > session
> >> > > is no longer replicated. What might be the issue? In status page of
> >> > apache
> >> > > server I see even if node status is OK session is not replicated to
> >> fail
> >> > > over node for second time.
> >> >
> >> > How do you replicate? Are you using Tomcat session clustering? Tomcat
> >> > 5.5 or Tomcat 6?
> >> >
> >> > Regards,
> >> >
> >> > Rainer
> >> >
> >> > ---------------------------------------------------------------------
> >> > To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> >> > For additional commands, e-mail: users-help@tomcat.apache.org
> >> >
> >> >
> >>
> >
> >
>

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