Motivations

So far we saw that DIET's hierarchy was mainly static: once the shape of the hierarchy chosen, and the hierarchy deployed, the only thing you can do is kill part of the hierarchy, or add new subtrees to the existing hierarchy. But whenever an agent is killed, the whole underlying hierarchy is lost. This has several drawbacks: some SeD will become unavailable, and if you want to reuse the machines on which those SeD (or agents) are, you need to kill the existing DIET element, and redeploy a new subtree. Another problem due to this static asignement of the parent/children links is that if you have an agent that is overloaded, you cannot move part of its children to an underloaded agent somewhere else in the hierarchy without once again killing part of the hierarchy, and deploying once again.