Skip to content
Juvix imports 

module arch.node.types.engine;

import prelude open;
import arch.node.types.identities open;
import arch.node.types.engine_environment open public;
import arch.node.types.engine_behaviour open public;

The type for engines

An engine is a computational unit with a specific name and behaviour, plus an initial environment, which comprises the specific state, the mailbox cluster, the acquaintances, and the timers. We refer to the type of engines as Engine, instantiated with the types for the local states, the mailboxes' state, the time handles, the action-label action, and the precomputation. We use the following notation to denote these type parameters:

  • S the type for the local states,
  • M the type for the mailboxes' state,
  • H the type for the time handles,
  • A the type for the action-label,
  • L the type for the precomputation, and
  • X the type for the external inputs.

Each engine, not its type, is associated with:

  • a specific name (unique across the system),
  • a specific behaviour, and
  • a declaration of its own execution context, that is, the specific state, the mailbox cluster, the acquaintances, and the timers.
type Engine (S M H A L X : Type) :=
  mkEngine {
    name : EngineName;
    initEnv : EngineEnvironment S M H;
    behaviour : EngineBehaviour S M H A L X
  };

Voting Engine

As an example, we could define an engine type for a voting system:

  • S could be a record with fields like votes, voters, and results.
  • The engine-specific message type might be a coproduct of Vote and Result.
  • The behaviour of this engine may include guarded actions such as: - storeVote to store a vote in the local state, - computeResult to compute the result of the election, and - announceResult to send the result to some other engine instances.

With each different election or kind of voters, we obtain a new engine instance, while the underlining voting system, the voting engine family, remains the same.

(Wiki) links on this page