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From Gomez Henri <>
Subject RE: [PROPOSAL Tomcat 4.x] Cluster
Date Thu, 11 Oct 2001 22:02:29 GMT
En réponse à Bip Thelin <>:

> Pasted below is an email I posted a few weeks ago where I
> responded to a similar question. Hope this might help.

Did you ever have considered using the web connector, mod_jk for
example, to forward serialized stuff from TC to web-server, when
needed, at answer time ?

It will help recover from a TC crash when using farm of TC 
(in load-balancing or fault-tolerant mode) .

For example :

Apache server use mod_jk and balance load between TC1, TC2, TC3.

After a session creation TC1 send both http anwser + serialized session
data to Apache. When session is updated, TC1 resend session datas.

TC1 crash and then Apache resend the request to TC2 + the previously
saved session stuff.

And it won't need to deploy multicast stuff.

ajp14 could be extended in such a way.

What do you think of that ?

> 	Bip Thelin
> ----------------------------------------------------------------
> > -----Original Message-----
> > From: "Peuß, Thomas" [] 
> >
> > [...]
> > can someone give me a hint where I can find information about 
> > the Tomcat 4.0
> > cluster-mode? I found the sources in the package 
> > org.apache.catalina.cluster
> > but I cannot find any docs about configuration of the feature.
> There aren't any documents that describe how to run Tomcat in
> cluster mode. I should advise you that the cluster package needs
> some improvements before it can be useful in a production environment.
> However.
> Add this under your <Host> in server.xml:
> <Cluster className="org.apache.catalina.cluster.StandardCluster"
>     multicastSocket="6789"
>     multicastAddress=""
>     checkInterval="5"
>     clusterName="myCluster"
>     debug="99"/>
> There's experimental support for replicating sessions in the
> cluster, edit/uncomment your <Manager> and change the className
> to: org.apache.catalina.session.DistributedManager.
> It currently only replicates *new* sessions. It doesn't replicate
> any changes made to the objects associated with your session.
> I had some problems getting multicasting to work under Linux and
> according to Sun it was a Linux kernel issue rather than a JDK issue.
> I have now switched to openBSD and hopefully I'll be able to continue
> the work and commit some code for the clustering package again.
> There's also an issue with the cookies if you want the cluster to
> be able to "continue" a replicated session that origined on a other
> machine in the cluster. I think that mod_jk might solve this with
> some sort of rewrite if you run it in loadbalancing mode? Maybe
> Henri Gomez or someone could comment on this?
> If you want to try it out and maybe submit some code/patches that
> would be gladly appreciated.
> 	Bip Thelin

Henri Gomez                 ___[_]____
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