>I am sure, my question was not very clear regarding security.

that is true, I'm sure you could limit this traffic with configuration on
your OS between your two servers.

set up machines to only access mcast and tcp traffic from certain IPs and
certain ports.

cause the feature you talk about, doesn't exist in Tomcat today

ok, I haven't tested replication on 5.5 yet myself, I've been to busy with
corporate world.
but from what I am reading, is that the replication valve is not issuing the
transfer or session deltas. Maybe something broke...we'll have to check
you do have the replication valve set up in server.xml right?

Filip

-----Original Message-----
From: Tomcat Newbie [mailto:[EMAIL PROTECTED]
Sent: Friday, September 03, 2004 11:36 PM
To: Tomcat Users List
Subject: RE: Tomcat 5.5 In-Memory Session Replication


Filip,

Thank you for your assistance. You are very helpful as usual.

> Make sure you have multicast enabled. This can be a little tricky if you
run
> on a multihomed host, but you can google it.

OK, that may not be that difficult on a single host, or so I hope. I
tried on Fedora Linux (ifconfig showed multicast enabled, but a route
was missing in my setup):

route add -net 224.0.0.0 netmask 224.0.0.0 dev lo

which now allows me to see servers joining. This roue basically means
that I am not using network, or so they say. :-) (One probably should
stop tomcat instances before changing network settings, since CPU use
shot almost to 100%, as noted in the docs.)


> are you kidding me, there are no "hostile" tomcats, only "friendly" ones.
> (slap yourself on the head if you configure tomcats on the same multicast
> address but you don't want them to be in the same cluster, after a few
> times, you'll have it figured out :)

I am sure, my question was not very clear regarding security. Example, I
use two servers for webhosting. If I understand anything about
multicasting, that would imply that every multicast-able server on the
LAN will be receiving the brodacast? So if there was another Tomcat
instance on the LAN, which happened to have mcastAddress same as my
cluster, would it not receive an invitation to join the cluster?
Apparently, setting TTL would limit the multicast at a router, however I
am not sure if it applies to this situation, when I am dealing basically
with a LAN.

I made some progress in a sense that I can see servers joining. I see
session created on one server and also on another server. Session
attributes do not replicate however (with a default replication filter
and useDirtyFlag=true). Often SessionListener reports the attribute
value of null, but a few times when it actually reported a real value,
it still did not replicate. So I can access app instances on each server
with the same cookie and session information is different.

Ed


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