Cluster Control API

This part of the API allows consumers to utilise a cluster and its resources.

The cluster operator issues a Warrant for this API which is bound by consumers. The resulting control interface may be used to allocate resources, and run netlets, and monitor status. Users of this interface are called Application Controllers, and netlets run using this interface are called Managed Netlets. Application Controllers are not necessarily Managed Netlets.

Measures may be taken to ensure that an application controller always exists. The cluster may be provided with a Warrant through which it can create an application controller if necessary. This mechanism is lease based, so that if an existing controller fails to renew its lease, a new controller will be created by binding the warrant. This mechanism detects both explicit failures, where the controller netlet terminates, or subtle failures, where the controller netlet merely malfunctions.

The API supports aggregation, allowing virtual clusters to be created using lower level clusters, in a manner transparent to the users of the cluster, and may not be implemented by specialised Hosting Services, which may substitute it for extended definitions of Managed Netlets and their behaviours.