Package net.sodacan.core.actorgroup

package net.sodacan.core.actorgroup

An ActorGroup contains a dynamic number of actors. However, actors are permanently assigned to one ActorGroup. An ActorGroup has a unique id which is an integer number from 1 to 2^32-1. (Actor assignment isn't completely permanent: A social media account might be a good example. Most users have a modest amount of activity which fits nicely using random ActorGroup assignment. But there will be an account that has achieved viral status and could require its own ActorGroup. Sodacan provides a way to do this using message routing and a form of replication.)

Any given ActorGroup, along with its contained Actors is only active on a single host in the network at any point in time. However, there will usually be zero or more **hot standby** replicas of the actor group. Standby ActorGroups are not used for load balancing in Sodacan. That is because Actors, by there nature, are the smallest unit of non-concurrency and require sequential access via message. As such, load balancing occurs automatically because work is by design broken into the smallest unit possible, the actor. On a big enough system (many CPUs) or small enough information model, every actor could have its own CPU.

An ActorGroup will have a primary replica running on some Host and a number of other replicas in various operating modes on other Hosts. A single Host will usually have a subset of ActorGroups and each ActorGroup could be in a different operating mode on a given Host. Since a single ActorGroup number can exist on more than one Host, an identifier called Host-ActorGroup is used by the Coordinator to describe the configuration of a running system.

HostBound ActorGroup

A special ActorGroup (number 0) is created by the Host, outside the list of ActorGroups that participate in the the movement from one Host to another. As such, a HostBound ActorGroup is not replicated.

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