On Thu, 4 Aug 2011, CLingan wrote:
Hello All
I am a novice user with CAS. I have couple of questions and looking forward
for some clarification or direction from this forum. Any idea is highly
appreciated.
The full CAS clustering as described on the wiki seemed like overkill to
me.
I used MySQL (a single server, although it replicates to a slave) as my
service registry. Somewhere I read that CAS will continue operating if
the service registry goes down, although obviously you won't be able to
modify services. This was an acceptable failure mode for us.
I used memcache+repcache as my ticket registry. I have 2 CAS nodes and
each node runs a copy of memcache+repcache. CAS connects to the local
instance of memcache and repcache replicates the cache between the nodes.
I use a Brocade ServerIron hardware load balancer in front of the 2 CAS
nodes.
Back to your questions:
1) My understanding is when CAS is used in a load balanced environment (like
running multiple tomcat instances and each instance having CAS installed in
them) , it is mandatory to have CAS clustered as described in
https://wiki.jasig.org/display/CASUM/Clustering+CAS
https://wiki.jasig.org/display/CASUM/Clustering+CAS .
Is that right ?
From what I know, the Tomcat clustering described on that wiki page will
handle replication of the internal Tomcat sessions. I don't think that is
strictly necessary. Without the session replication, users could see a
hiccup when a node fails, but with the ticket cache still available, CAS
should be able to continue honoring the various tickets it has issued.
Perhaps someone more knowledgeable in CAS can chime in on this.
2. I am following the above mentioned link to cluster CAS and would like
to know if TicketCache Replication is a mandated step ? Since CAS stores
everything thing is the session is not enough to have the Tomcat's
session replicated ?
You definitely want your ticket cache to be replicated. The ticket cache
must be the same for all instances of CAS.
3. Is it possible to do a TicketCache Replication when using the Default
Ticket registry ?
I don't think so... Isn't that just an in-memory hash?
Andy
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