wechaty-cqrs v0.12.5

CQRS Wechaty

A event-driven architecture wrapper for Wechaty that applies the CQS principle by using separate Query and Command messages to retrieve and modify the bot state, respectively.

Image source: Introducing Derivative Event Sourcing

Command Query Responsibility Separation (CQRS)

Command query responsibility separation (CQRS) generalises CQS to message-driven and event-driven architectures: it applies the CQS principle by using separate Query and Command messages to retrieve and modify data, respectively.

— Wikipedia: Command–query separation

Image source: CQRS (command query responsibility segregation)

Usage

Install

npm install wechaty-cqrs wechaty

Quick start

Here's the CQRS version of the Wechaty ding/dong bot:

import * as WECHATY from 'wechaty'
import * as CQRS    from 'wechaty-cqrs'

import { filter }   from 'rxjs/operators'

const wechaty = WECHATY.WechatyBuilder.build()
await wechaty.init()

const bus$ = CQRS.bus(wechaty)

bus$.pipe(
  filter(CQRS.isActionOf(CQRS.events.messageReceivedEvent)),
  filter(event => event.payloads.type === CQRS.sayable.type.Text),
  filter(event => event.payloads.payload === 'ding')
).subscribe(ding => bus$.next(
  CQRS.commands.sendMessage(
    ding.payload.talkerId,
    CQRS.sayable.text('dong'),
  ),
))

await wechaty.start()

Diagrams

graph LR
  classDef event fill:DarkGoldenRod
  classDef command fill:blue
  classDef query fill:green

  subgraph Command
    C(VerbNounCommand):::command
  end

  subgraph Message
    MC(NounVerbedMessage)
    MQ(NounGotMessage)
  end
    
  subgraph Query
    Q(GetNounQuery):::query
  end

  subgraph Event
    ER(ReceivedEvent):::event
  end

  C-->MC

  ER-->ER

  Q-->MQ

Command

sequenceDiagram
    participant Bus
    participant Redux
    participant Wechaty

    Bus->>Redux: ExecuteCommand
    Redux->>Wechaty: Call
    Wechaty->>Redux: Call Return (void)
    Redux->>Bus: CommandExecutedMessage

Query

sequenceDiagram
    participant Bus
    participant Redux
    participant Wechaty

    Bus->>Redux: GetNounQuery
    Redux->>Wechaty: Call
    Wechaty->>Redux: Call Return (value)
    Redux->>Bus: NounGotMessage

Event

sequenceDiagram
    participant Bus
    participant Redux
    participant Wechaty

    Wechaty->>Redux: ReceivedEvent
    Redux->>Bus: ReceivedEvent

API Docs

TBW

Resources

• class-transformer - Decorator-based transformation, serialization, and deserialization between objects and classes.

History

main v0.1 (Mar 11, 2022)

Unit tests all passed, DevOps enabled.

v0.0.1 (Mar 6, 2022)

Init README & Draft design.

Author

Huan LI (李卓桓), Microsoft Regional Director, zixia@zixia.net

Copyright & License

• Code & Docs © 2022 Huan (李卓桓) \zixia@zixia.net\
• Code released under the Apache-2.0 License
• Docs released under Creative Commons