>My company is getting ready to move to a clustered environment. We >currently use session variables for our shopping cart. > >I keep seeing posts about needing to convert to client variables for load >balancing, despite the fact that the CF5 Advanced CF Administration manual >(chp 12, Configuring ColdFusion Clusters) states: > >"To ensure that users are not redirected from the server on which they >start their session, ClusterCATS provides a built-in feature for enabling >session-aware load balancing." > >So ... I'm getting nervous here. Does anyone have experience with >session-aware load balancing in ClusterCATS? Is there some reason that >everyone is recommending client variables? >
I think that people are recommending client variables because sticky sessions have some limitations if you're aiming for a true load-balanced environment. Sticky sessions work by pinning a user to one server throughout their session. That's fine if you don't have templates that perform rigorous routines on your site. But if you do, problems can arise. If one user comes and starts hogging a lot of resources on one server and is using sesson variables, subsequent requests will be re-directed to another server. But since they are now tied to a server because of sticky-sessions, you now have several people on one machine and one on the other for the remainder or each of their sessions. True balance can't be maintained. What would have if some of those subsequent users started running their own complex templates? You'd now have one server getting pummeled and the other just sitting there (relatively speaking). Client variables offer you the ability to not have to worry about this scenario. Simply store the variables in a shared datasource and you don't have to worry about pinning a user to one machine. If you have complex structures to store, use WDDX to store them in the client store. It's super quick and not hard to implement. I hope this makes a bit of sense, as the visualization can be hard to communicate over e-mail! Hope this helps, Dave. _________________________________________________________________ Send and receive Hotmail on your mobile device: http://mobile.msn.com ______________________________________________________________________ Get the mailserver that powers this list at http://www.coolfusion.com FAQ: http://www.thenetprofits.co.uk/coldfusion/faq Archives: http://www.mail-archive.com/[email protected]/ Unsubscribe: http://www.houseoffusion.com/index.cfm?sidebar=lists
