Decentralized Instant Messaging Protocol (Dart)

Dependencies

Name	Version	Description
Ming Ke Ming (名可名)		Decentralized User Identity Authentication
Dao Ke Dao (道可道)		Universal Message Module

Examples

Extends Command

• Handshake Command Protocol
  0. (C-S) handshake start
  1. (S-C) handshake again with new session
  2. (C-S) handshake restart with new session
  3. (S-C) handshake success

import 'package:dimp/protocol.dart';


class HandshakeState {

  static const int START   = 0;  // C -> S, without session key(or session expired)
  static const int AGAIN   = 1;  // S -> C, with new session key
  static const int RESTART = 2;  // C -> S, with new session key
  static const int SUCCESS = 3;  // S -> C, handshake accepted

  static int checkState(String title, String? session) {
    if (title == 'DIM!'/* || title == 'OK!'*/) {
      return SUCCESS;
    } else if (title == 'DIM?') {
      return AGAIN;
    } else if (session == null) {
      return START;
    } else {
      return RESTART;
    }
  }
}


///  Handshake command: {
///      type : i2s(0x88),
///      sn   : 123,
///
///      command : "handshake",    // command name
///      title   : "Hello world!", // "DIM?", "DIM!"
///      session : "{SESSION_KEY}" // session key
///  }
abstract interface class HandshakeCommand implements Command {

  static const String HANDSHAKE = 'handshake';

  String get title;
  String? get sessionKey;

  int get state;

  static HandshakeCommand start() =>
      BaseHandshakeCommand.from('Hello world!');

  static HandshakeCommand restart(String session) =>
      BaseHandshakeCommand.from('Hello world!', sessionKey: session);

  static HandshakeCommand again(String session) =>
      BaseHandshakeCommand.from('DIM?', sessionKey: session);

  static HandshakeCommand success(String? session) =>
      BaseHandshakeCommand.from('DIM!', sessionKey: session);

}


class BaseHandshakeCommand extends BaseCommand implements HandshakeCommand {
  BaseHandshakeCommand(super.dict);

  BaseHandshakeCommand.from(String title, {String? sessionKey})
      : super.fromName(HandshakeCommand.HANDSHAKE) {
    // text message
    this['title'] = title;
    // session key
    if (sessionKey != null) {
      this['session'] = sessionKey;
    }
  }

  @override
  String get title => getString('title') ?? '';

  @override
  String? get sessionKey => getString('session');

  @override
  int get state => HandshakeState.checkState(title, sessionKey);

}

Extends Content

import 'package:dimp/protocol.dart';


///  Application Customized message: {
///      type : i2s(0xA0),
///      sn   : 123,
///
///      app   : "{APP_ID}",  // application (e.g.: "chat.dim.sechat")
///      extra : info         // others
///  }
class ApplicationContent extends BaseContent implements AppContent {
  ApplicationContent(super.dict);

  ApplicationContent({required String app}) : super.fromType(ContentType.APPLICATION) {
    this['app'] = app;
  }

  @override
  String get application => getString('app') ?? '';

}

Extends ID Address

• Examples in dim_plugins

Copyright © 2023 Albert Moky