Message protobuf schema

message Message {
    oneof content {
	    … 
    }
}

message PrePrepare {
    uint64 View = 1;
    uint64 Seq = 2;
    bytes Payload = 3;
    bytes Header = 4;
    bytes Metadata = 5;	
}

message Prepare {
    uint64 View = 1;
    uint64 Seq = 2;
    bytes Digest = 3;
}

message Commit {
    uint64 View = 1;
    uint64 Seq = 2;
    bytes Digest = 3;
    bytes Signature = 4; 
}

message Error {
    uint64 View = 1;
    uint64 Seq = 2;
    bytes Digest = 3;
    string reason = 4;
}

message ViewChange {
    uint64 NextView = 1;
}

message ViewData {
    uint64 NextView = 1;
}

message NewView {
    uint64 NextView = 1;
}