Abstract: An availability system is provided that includes a hierarchy of controllers for providing event notifications relating to availability of components of a scalable MPP system. A controller receives a subscription from a child controller that identifies an event type and a generator. The controller stores in a subscription store an indication that the subscription has been received from the child controller. When a parent controller has not yet been notified of a subscription with a matching event type and generator as indicated by the subscription store, the controller sends the subscription to the parent controller. When the parent controller has already been notified of a subscription with a matching event type and generator as indicated by the subscription store, the controller suppresses the sending of the subscription to the parent controller.

Abstract: An availability system is provided that includes a hierarchy of controllers for providing event notifications relating to availability of components of a scalable MPP system. A controller receives a subscription from a child controller that identifies an event type and a generator. The controller stores in a subscription store an indication that the subscription has been received from the child controller. When a parent controller has not yet been notified of a subscription with a matching event type and generator as indicated by the subscription store, the controller sends the subscription to the parent controller. When the parent controller has already been notified of a subscription with a matching event type and generator as indicated by the subscription store, the controller suppresses the sending of the subscription to the parent controller.

Abstract: A diffracting token router for executing a correctness invariant. The diffracting token router is connected to at least one producer of tokens and at least two consumers of tokens. The diffracting token router includes an array of inlet wires, an array of outlet wires, a diffracting prism connected to the array of inlet wires and the array of two outlet wires and a decision decider connected to the diffracting prism and the at least two outlet wires. The diffracting taken router has two operative modes. In its first operative mode, two or more tokens arrive at the diffracting prism in a diffracting collision manner according to the correctness invariant, and are thereafter routed to the array of output wires according to the correctness invariant.