replica

type Dispatcher interface {
	Dispatch(shardHash sig.Hash, action state.Action)
}

type Replica interface {
	Init()
	Sync(commit block.Commit) bool
	Transition(transition state.Transition)
}

type Validator interface {
	// ValidatePropose validates a state.Propose and returns true if
	// the block is valid.
	// For a SignedBlock to be valid:
	// 1. must not be nil
	// 2. have valid blockTime, Round, and Height
	// 3. have a valid signature
	// 4. signatory belongs to the same shard
	// 5. parent header maps to the block at head of the shard's blockchain
	ValidatePropose(propose block.SignedPropose) bool

	ValidatePreVote(preVote block.SignedPreVote) bool

	// ValidatePolka validates a polka and its signatures and returns true if
	// the polka is valid.
	// For a Polka to be valid:
	// 1. must not be nil
	// 2. have a non-negative Round and Height
	// 3. all the signatures inside the polka must be valid and
	//    belong to signatories within the same shard
	// 4. have a valid block (if block is not nil)
	//
	// validatePolka assumes that `polka.Signatures` are ordered to match
	// the order of `polka.Signatories`.
	ValidatePolka(polka block.Polka) bool

	ValidatePreCommit(preCommit block.SignedPreCommit) bool

	ValidateCommit(commit block.Commit) bool
}