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From Sumedh Sakdeo <sumedhsak...@gmail.com>
Subject Re: Apache Server failover and session replication
Date Thu, 03 Sep 2009 03:13:07 GMT
Shaun,
 Yes we have a user session object created when user logs on with proper
credentails.
For ex: At startup of two servers lets say user A has logged in.
As you are saying the SSO information is propagated while all instances are
running. So when for first time when tomcat which was handling request goes
down, this session object is successfully handled by other tomcat instance.
But when first instance comes up, and due to some reason second instance
which was processing sticky requests goes down this session object is lost.
Our problem is that this failback should happen correctly, and we find this
a general requirement, so do tomcat6 support such a scenario?

I have been sratching my head from past few days to fix this. What kind of
solution have you written for this? Could you please share?

Thanks for your time,
Ciao,
Sumedh

On Thu, Sep 3, 2009 at 6:26 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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