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From Shaun Senecal <ssenecal.w...@gmail.com>
Subject Re: Apache Server failover and session replication
Date Fri, 04 Sep 2009 00:01:11 GMT
I cant answer for sure.  As I said, my experience with clustering is
limited, although the only problem we had was specifically with the SSO
data.  Once I extended ClusterSSO to automatically request all known SSO
data from the cluster, the problem went away.




On Thu, Sep 3, 2009 at 9:57 PM, Sumedh Sakdeo <sumedhsakdeo@gmail.com>wrote:

> Can anyone help in these regards?
> Thanks in advance,
> Sumedh
>
> On Thu, Sep 3, 2009 at 8:52 AM, Sumedh Sakdeo <sumedhsakdeo@gmail.com
> >wrote:
>
> > 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
> >> >> >
> >> >> >
> ---------------------------------------------------------------------
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> >> >> > For additional commands, e-mail: users-help@tomcat.apache.org
> >> >> >
> >> >> >
> >> >>
> >> >
> >> >
> >>
> >
> >
>

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