Is there an availability impact of doing stateful or stateless routing at Web Cache level?
If the backend servers are all performing stateless requests mod_plsql, Portal etc. it is recommended to set a stateless routing at Web Cache. In this scenario Web Cache routes across all backend application servers, independent of which server serviced the previous request from the same browser (session). In case the backend servers are stateful ex. a shopping cart in a J2EE application the answer to Web Cache routing setup is less clear. If the backend J2EE servers are clustered, it is still recommended to do stateless routing at the Web Cache level. This is because OHS (with mod_oc4j) contains a smart routing algorithm that understands islands and state replication. And this information is already contained in the cookie. Thus, even if Web Cache routes to a different OHS, that OHS will route it to the correct OC4J. The advantage of this setup is that it provides better availability: ยท If backend server machine is down, stateless routing enables Web Cache to route to a different mach
