Google Protobuf

Specification: https://developers.google.com/protocol-buffers

Protocol Definition

The .proto Protocol Buffers Version Language Specification of the payload used by VILLASnode is available in the Git repository:

https://github.com/VILLASframework/node/blob/master/lib/formats/villas.proto

node/lib/formats/villas.proto

// Protobuf schema based on msg_format.h
//
// @file
// Author: Steffen Vogel <post@steffenvogel.de>
// SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
// SPDX-License-Identifier: Apache-2.0

syntax = "proto2";

package villas.node;

message Message {
  repeated Sample samples = 1;
}

message Sample {
  enum Type {
    DATA = 1;				            // Message contains float / integer data values
    START = 2;			            // Message marks the beginning of a new simulation case
    STOP = 3;				            // Message marks the end of a simulation case
  };

  required Type type = 1 [default = DATA];
  optional uint64 sequence = 2; // The sequence number is incremented for consecutive samples.
  optional Timestamp ts_origin = 3;
  optional Timestamp ts_received = 4;
  optional bool new_frame = 5;
  repeated Value values = 100;
}

message Timestamp {
  required uint32 sec = 1;		  // Seconds since 1970-01-01 00:00:00
  required uint32 nsec = 2;		  // Nanoseconds of the current second.
}

message Value {
  oneof value {
    double f = 1;				        // Floating point values.
    int64 i = 2;				        // Integer values.
    bool b = 3;				          // Boolean values.
    Complex z = 4;			        // Complex values.
  }
}

message Complex {
  required float real = 1;		  // Real component
  required float imag = 2;		  // Imaginary component
}

Implementation

The source code of the format-type is available here: https://github.com/VILLASframework/node/blob/master/lib/formats/protobuf.cpp

Configuration

delimiter	string
real_precision	integer Default: 17 Output all real numbers with at most n digits of precision. The valid range for this setting is between 0 and 31 (inclusive), and other values result in an undefined behavior. By default, the precision is 17, to correctly and losslessly encode all IEEE 754 double precision floating point numbers.
ts_origin	boolean Default: true If set, include the origin timestamp in the output.
ts_received	boolean Default: true If set, include the received timestamp in the output.
sequence	boolean Default: true If set, include the sequence number in the output.
data	boolean Default: true If set, include the data in the output.
offset	boolean Default: true If set, include the offset between origin and received timestamp in the output.

{

• "delimiter": "string",
• "real_precision": 17,
• "ts_origin": true,
• "ts_received": true,
• "sequence": true,
• "data": true,
• "offset": true

}

Example Configuration

node/etc/examples/formats/protobuf.conf

nodes = {
    node = {
        type = "file"
        uri = "/dev/null"

        format = "protobuf"
    }
}