this is a reply to kevin duffeys questions regarding sessionfailover that i thought might be of interest to others on the list ----- Original Message ----- From: "Morten Wilken" <[EMAIL PROTECTED]> To: "Duffey, Kevin" <[EMAIL PROTECTED]> Sent: Wednesday, August 22, 2001 12:25 PM Subject: Re: Orion and session fail-over.. > > ----- Original Message ----- > From: "Duffey, Kevin" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Wednesday, August 22, 2001 2:57 AM > Subject: Orion and session fail-over.. > > > hi kevin, as i said in my post, what i did was to add the load-on-startup to > to web-app tag... and then i found that the other servers started recieving > right away. > i run all my apps in the default web site.... i dont know if that factors > into it aswell.. i suppose i shouldn't. > im not sure which of my posts you're referring to as i posted a couple of > them about this, but i followed the clustering howto from orion, plus i > addede the load-on-startup=true attribute. > you could post me your configs and i could have a look :-) > > as for how orion implements loadbalancing, i wrote a small multicast client > and set it up to listen to the port, plus i added the -debug flag to see > what really went on, and it seems that it replicates the object in the > session when you change it, and not the entire session. and ofcourse it only > replicates it to its own clusterisland. > this would mean tht if you had a 500mb session (which i wouldnt recommend > :-)) then either you have a bunch of objects that each is replicated when > they're accesed, or you have a 500mb object in your session, in which case > it would replicate it all. > > another thing that i had to change in my original design was that i had to > explicitly set the session object in order for it to be flagged for > replication ie: > > not: > > object a =session.getAttribute("someObject); > a.method(); > > but: > object a =session.getAttribute("someObject); > a.method(); > session.setAttribute("someObject, a); > > hope some of this helps, and if not please write me again :-) > anf good luck with your book > > sincerely > Morten Wilken > > Hi there, > > > > I just posted a message to the list about clustering. I happened to be > > deleting the 7000 emails I have in archive of the Orion-list and decided > to > > search for clustering. I cam across your thread, and I am having EXACTLY > the > > same problem you are. The only difference is, I have the load-on-startup > in > > my <web-site> tag, and I am still seeing the same results. One server > shows > > the "Sending..." the other one shows nothing. Not sure if it is supposed > to > > or not. I would list my config, but its at home. I am hoping you can help > me > > figure this out as I am writing a chapter on scalability using a simple > cart > > based web-app, and I want to test it for session fail-over, and explain > how > > it works in this chapter. > > > > In my email to the list I am trying to find out how in general servlet > > containers fail over. When you use the setAttribute() call, does it copy > the > > entire session of that user to the other server(s) in the cluster? Or does > > it just copy the one object and the other server(s) are smart enough to > > insert it into the right session? OR..worse..does it copy ALL sessions of > > all users to the other servers??!! If so, what happens when you have a > > session of 500MB of objects..does it take like 2 minutes to replicate the > > session, bring Orion to a crawl, etc? > > > > Thanks for your help and info. > > > > >