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From Shaun Senecal <ssenecal.w...@gmail.com>
Subject Re: Apache Server failover and session replication
Date Thu, 03 Sep 2009 00:59:47 GMT
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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>> >
>> >
>>
>
>

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