ReadPacket

Kind: Interface

Source: packages/microservices/interfaces/packet.interface.ts

Part of: Microservices

ReadPacket<T> represents a normalized incoming microservice message. It carries the routing pattern used to identify the handler and the typed data payload passed to that handler.

Properties

Diagram

mermaid
graph LR
  Client[Microservice Client] --> Packet[ReadPacket<T>]
  Packet --> Pattern[pattern: message route]
  Packet --> Data[data: T payload]
  Pattern --> Handler[Matching Message Handler]
  Data --> Handler

Usage

ts
import type { ReadPacket } from './interfaces/packet.interface';

interface CreateUserPayload {
  email: string;
  name: string;
}

const packet: ReadPacket<CreateUserPayload> = {
  pattern: 'users.create',
  data: {
    email: 'ada@example.com',
    name: 'Ada Lovelace',
  },
};

function handleCreateUser(message: ReadPacket<CreateUserPayload>) {
  if (message.pattern !== 'users.create') {
    return;
  }

  return createUser(message.data);
}

AI Coding Instructions

• Use a generic type parameter for data so message payloads remain strongly typed.
• Treat pattern as the message-routing identifier; ensure it matches the corresponding microservice handler pattern.
• Validate or transform data at the application boundary before relying on its fields.
• Avoid assuming a specific pattern type, because it is intentionally declared as any.

How it works

ReadPacket<T = any> is a generic TypeScript interface representing the input portion of a microservice packet: a required pattern field typed as any and a required data field typed as T. If no type argument is supplied, data is any. It declares no methods, validation, error handling, or runtime side effects itself. [packet.interface.ts:5-8]

It is the base type for both request and event packet aliases. OutgoingRequest and IncomingRequest add a string id through intersection with PacketId; OutgoingEvent and IncomingEvent are ReadPacket directly. [packet.interface.ts:1-3] [packet.interface.ts:17-20]

ClientProxy.send() and emit() construct packets as { pattern, data } only after rejecting null or undefined values for either argument with InvalidMessageException. [client-proxy.ts:86-101] [client-proxy.ts:111-120] For request flows, assignPacketId() mutates the passed packet with a generated id and returns it as ReadPacket & PacketId. [client-proxy.ts:160-163]

The interface is exported from the microservices interfaces barrel. [interfaces/index.ts:1-12]