NestJS Microservices

import { NestFactory } from "@nestjs/core";
import { MicroserviceOptions, Transport } from "@nestjs/microservices";
import { MathModule } from "./math.module";

async function bootstrap() {
  const app = await NestFactory.createMicroservice<MicroserviceOptions>(
    MathModule,
    {
      transport: Transport.TCP,
      options: { host: "127.0.0.1", port: 3001 },
    },
  );
  await app.listen();
}
bootstrap();

import { Controller } from "@nestjs/common";
import { MessagePattern, Payload } from "@nestjs/microservices";

@Controller()
export class MathController {
  @MessagePattern({ cmd: "add" })
  add(@Payload() data: { a: number; b: number }): number {
    return data.a + data.b;
  }
}

import { Module } from "@nestjs/common";
import { ClientsModule, Transport } from "@nestjs/microservices";
import { AppController } from "./app.controller";

@Module({
  imports: [
    ClientsModule.register([
      {
        name: "MATH_SERVICE",
        transport: Transport.TCP,
        options: { host: "127.0.0.1", port: 3001 },
      },
    ]),
  ],
  controllers: [AppController],
})
export class AppModule {}

import { Controller, Get, Inject } from "@nestjs/common";
import { ClientProxy } from "@nestjs/microservices";
import { lastValueFrom } from "rxjs";

@Controller("math")
export class AppController {
  constructor(
    @Inject("MATH_SERVICE") private readonly client: ClientProxy,
  ) {}

  @Get()
  async add() {
    const result = await lastValueFrom(
      this.client.send({ cmd: "add" }, { a: 5, b: 3 }),
    );
    return { result }; // 8
  }
}

# run service প্রথমে
node dist/main.js   # or npm run start:prod

# তারপর main app
npm run start:dev
# GET http://localhost:3000/math → { result: 8 }