> From: Alex Karasulu [mailto:[EMAIL PROTECTED] > > > From: Leo Sutic [mailto:[EMAIL PROTECTED] > > > > Seriously, though, I have found it easier to put in the > > container: > > > > 1. The ability to uniquely name each component. > > 1. Uniquely identify (name adds human connotation)?
Not neccessarily. In order to replicate state from a component in one JVM to a component in another JVM, you must be able to name components in the sense that you must be able to find the peer in the other JVM of a component in the first JVM in order to replicate anything. For example, if you have two VMs - one main, one failover. The container replicates state. Now, if the component changes state, the container must somehow be able to tell the other VM that *this* component has changed in *that* way. In short, the containers must be able to somehow identify *what* component they are talking about, before they can start agreeing on what the state of that component is. (One way of doing this is to use the ROLE or some other component id.) The name need not be human-understandable, but as you can see, there must be some concept of naming in order for us to associate state with *something*. > I think generalized failover out of the box can be achieved. It is possible, but makes it difficult to code. A way out is to only replicate certain state. For example, if component A reaches a state where its rules say it should send an email to the administrator, you don't want the failover to send an email of its own. (Or have each node in the cluster send an email.) I have solved this with a message-passing style where certain method calls get reliably replicated across the cluster (if a node is down it will play catch-up and so on). So I have to keep track of whether something is executing on the local node, or all over the cluster. Fortunately, it isn't that hard to keep track of such things. /LS --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
