Message protobuf schema

message Message {
    oneof content {
	    … 
    }
}

message PrePrepare {
    uint64 view = 1;
    uint64 seq = 2;
    Proposal proposal = 3;
}

message Prepare {
    uint64 view = 1;
    uint64 seq = 2;
    bytes digest = 3;
}

message Commit {
    uint64 view = 1;
    uint64 seq = 2;
    bytes digest = 3;
    Signature signature = 4;
}

message Error {
    uint64 view = 1;
    uint64 seq = 2;
    bytes digest = 3;
    string reason = 4;
}

message ViewChange {
    uint64 next_view = 1;
    string reason = 2;
}

message ViewData {
    uint64 next_view = 1;
    Proposal last_decision = 2;
    repeated Signature last_decision_signatures = 3;
    PrePrepare last_pre_prepare = 4;
    Prepare last_prepare = 5;
    Commit last_commit = 6;
}

message SignedViewData {
   bytes raw_view_data = 1;
   Signature signature = 2;
}

message NewView {
    repeated SignedViewData signed_view_data = 2;
}

message HeartBeat {
    int64 view = 1;
    uint64 seq = 2;
}

message Signature {
    uint64 signer = 1;
    bytes value = 2;
}

message Proposal {
    bytes header = 1;
    bytes payload = 2;
    bytes metadata = 3;
    uint64 verification_sequence = 4;
}