On Jul 31, 2008, at 5:45 AM, Siofra wrote:
Hello,
Our Jetspeed portal application is running on 2 servers, A & B.
Application
requests over HTTP are load-balanced between the 2 servers.
We have noticed unusual behavior if multiple browser sessions are
opened for
our application URL.
For example, if I open 6 browser sessions and I am the only user in
the
system, I will invariably get 3 sessions running from server A and 3
running
from server B. When I make portal changes in a browser that's
running on
server A, the changes are visible when I refresh the other 2 browser
sessions running on server A. However, the changes are not visible in
browsers running on the other server B even after refresh. Both these
application server instances share the same Jetspeed database, so I
suspect
that caching on the Jetspeed level is responsible for the discrepancy
between the 2 servers.
If I leave the system for a day or so, the 2 servers become
synchronized
again and changes made previously on server A are propagated over to
the
instance on server B. This is not ideal because a delay in showing
updated
portal preferences would impact user experience.
If it is a caching issue, how long before the cache expires by
default? Can
I reduce the lifetime of the cache or force a refresh?
Is it an absolute requirement that the same user will login from
different locations and share session state? We've had this question
asked before and it seems to open up a can of worms.
Jetspeed relies on the servlet container to create sessions. If a user
logs in on server A from web-client B, then the same user logs in on
server A from web-client B, they will get different sessions, even
though they are the same user.
If you use Tomcat's clustering features it will handle the typical
scenario of web-client A hits the cluster, gets routed to server A,
next time web-client A hits the cluster, gets routing to server B, and
having the same seamless session attribute available.
See more here:
http://tomcat.apache.org/tomcat-5.5-doc/cluster-howto.html
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