typed_messages 1.0.0 typed_messages: ^1.0.0 copied to clipboard
A simple piece of data with encoder and decoder
TypedMessages #
A simple piece of data with encoder and decoder
Messages #
Message is a piece of information can be shared between node and peer
Lets define a message
class ClientInfoMessage extends Message {
const ClientInfoMessage(this.name, this.avatar, this.clientId)
: assert(
name.length <= 20,
'client info name can not exceed 20bytes : ${name.length}',
);
final int clientId; // 20 bytes Uint
final String name; // bytes length in range [0, 20]
final int avatar; // 2 bytes Uint
}
Prototypes #
Prototypes are used to encode messages before send also validate and decode incoming messages
const int kClientInfoMessageId = 0;
// define or assign the prototype into the __MessagesPrototypes__ singleton
IMessagePrototype.definePrototype(const ClientInfoMessagePrototype());
class ClientInfoMessagePrototype implements IMessagePrototype<ClientInfoMessage> {
const ClientInfoMessagePrototype();
@override
Uint8List encode(ClientInfoMessage message) {
final writer = BytesWriter(22 + message.name.length);
writer.writeSingleByte(kClientInfoMessageId);
writer.writeSingleByte(message.name.length);
writer.writeText(message.name);
writer.writeUint(message.avatar, 2);
writer.writeUint(message.clientId, 20);
return writer.toBuffer();
}
@override
ClientInfoMessage decode(Uint8List bytes) {
final reader = BytesReader(bytes);
final int nameLength = reader.readSingleByte(1);
final String name = reader.readText(2, nameLength);
final int avatar = reader.readUint(2 + nameLength, 2);
final int id = reader.readUint(4 + nameLength, 20);
return ClientInfoMessage(name, avatar, id);
}
@override
bool validate(Uint8List bytes) {
final reader = BytesReader(bytes);
if (reader.length < 22 || reader.length > 42) return false;
final int id = reader.readSingleByte(0);
final int nameLength = reader.readSingleByte(1);
return id == kClientInfoMessageId && nameLength >= 0 && nameLength <= 20;
}
}
BytesWriter / BytesReader #
BytesWriter and BytesReader are util classes
Usage #
Now after creating ClientInfoMessage class and defining its prototype ClientInfoMessagePrototype using IMessagePrototype.defineProtoype
We have 2 ways to encode and decode data
Method1 Message abstract class #
final message = ClientInfoMessage("My Client", 0, 568978596);
final Uint8List bytes = Message.encode(message);
final ClientInfoMessage? decodedMessage = Message.decode(bytes);
Method2 using MessagesPrototypes singleton and prototypes directly #
final instance = MessagesPrototypes.instance;
final message = ClientInfoMessage("My Client", 0, 568978596);
// encode
final Uint8List? bytes = instance.encodeMessage(message);
// decode
final ClientInfoMessage? decodedMessage = instance.decodeBytes(bytes!);
// use defined prototype
final IMessagePrototype<ClientInfoMessage>? prototype = instance.findPrototypeByMessageType<ClientInfoMessage>();
prototype.encode(message);
prototype.decode(bytes!);
prototype.validate(bytes!);