What are WADIs goals?
In the Web tier, we can crystallise WADI’s goals into two stages: • To be able to walk into your web farm and ‘ctl-c’ any webcontainer node without losing any HttpSessions (i.e. customers). • To be able to walk into the same web farm and ‘kill -9’ any webcontainer node without losing any HttpSessions (i.e. customers). The first of these two cases is important because it allows easy maintenance of existing h/w or s/w. This may seem a trivial requirement, but many existing solutions are time-consuming and/or error-prone (involving draining sessions off target nodes over long periods etc.), to the point that many sites simply accept that maintenance will impact quality of service. The second of these two cases deals with a more exceptional case – the catastrophic failure of a webcontainer node. As online competition for business increases, systems are being required to provide higher and higher levels of availibility. This can be critical in particular areas. The ability to preserve web-t
