I. Application background:

Protobuf is Google’s format for data exchange, which is language independent and platform independent.


  • The advantage of JSON is that it is smaller than XML format, the transmission efficiency is much higher than XML, and the readability is good.
  • XML has the advantage of being readable and easy to parse.
  • Protobuf has the advantages of fast transfer (said to be 10-20 times faster than XML and JSON for large amounts of data), small serialized size compared to JSON and XML, cross-platform multi-language support, message format upgrade and compatibility is good, and fast serialization and deserialization.


  • The downside of JSON is that it’s not particularly efficient (faster than XML, but much slower than Protobuf).
  • The disadvantage of XML is that it is inefficient and consumes too much resources.
  • The downside of the Protobuf is that it’s not very easy to use.

In a scenario that requires a large amount of data to be transmitted, if there is a large amount of data, protobuf can significantly reduce the amount of data to be transmitted, reducing the network I/O, and thus reducing the time spent on the network transmission. Protobuf was a good choice given the amount of message data that would be required for a social focused product, and the need to save traffic.

Second, the use of

1. Import the Protobuf library


. protobuf:1.01.

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2. Write proto files


syntax = "proto3";
package socket;

// Send a chat message
message Message {
  string eventId = 1;
  string from = 2;
  string to = 3;
  string createAt = 4;
  string type = 5;
  string body = 6; m }// Receive the chat message
message AckMessage {
  string eventId = 1;
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3. Generate proto related Model


protoc --dart_out=. socket.message.proto
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4. Code and send messages

A. Prepare the Protobuf object

Message message = Message();
message.eventId = '# # # #';
message.type = 'text';
message.body = 'hello world';
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P. rotobufUtil coding

/// Data encoding
static List<int> encode(int type, var content) {
    ByteData data = ByteData(MESSAGE_HEADER_LEN);
    data.setUint16(0, type, Endian.little);
    List<int> msg = data.buffer.asUint8List() + content.writeToBuffer().buffer.asUint8List();
    return msg;

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C. to send messages

/// send
sendSocket(int type, var content) async {
    IOWebSocketChannel channel = await SocketService.getInstance().getChannel();
    if (channel == null) return;
    List<int> msg = ProtobufUtil.encode(type, content);

sendSocket(11, message)
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5. Receive and decode messages

A. the decoding

  /// The data decoding
  static DecodedMsg decode(data) {
    Int8List int8Data = Int8List.fromList(data);
    Int8List contentTypeInt8Data = int8Data.sublist(0, MESSAGE_HEADER_LEN);
    Int8List contentInt8Data = int8Data.sublist(MESSAGE_HEADER_LEN, int8Data.length);
    int contentType = contentTypeInt8Data.elementAt(0);

    GeneratedMessage content;
    switch (contentType) {
      case 10:
        content = AckMessage.fromBuffer(contentInt8Data);
      case 11:
        content = Message.fromBuffer(contentInt8Data);

    DecodedMsg decodedMsg;
    if(contentType ! =null&& content ! =null) {
      decodedMsg = DecodedMsg(
        contentType: contentType,
        content: content,
    return decodedMsg;

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B. to receive message

  channel.stream.listen((data) {
    DecodedMsg msg = ProtobufUtil.decode(data);

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End, scatter flowers 🎉