Hizmetler Arası İletişim
Olay tabanlı ve istek-yanıt mekanizmaları dâhil olmak üzere mikro hizmetler arasında etkili iletişim kalıplarını uygulayın.
Hizmetler Arası İletişim, CoddyKit'te ücretsiz bir NestJS Enterprise Backend APIs dersidir. Bu, 3 dersinin 3. dersidir. Aşağıdan dersin tamamını ücretsiz okuyabilir, sonra tarayıcıda yerleşik kod editörü ve 7/24 yapay zeka koçu ile uygulamalı olarak pratik yapabilirsin. Bu, NestJS Enterprise Backend APIs öğrenme yolunun bir parçasıdır ve ilerlemeniz web ve CoddyKit uygulaması arasında senkronize olur. NestJS Enterprise Backend APIs kursu toplamda 3 dersten oluşur.
Bu dersin bazı bölümleri henüz çevrilmemiş olup İngilizce olarak gösterilmektedir.
Microservices Need to Talk
Microservices are designed to be independent, but they often need to collaborate to complete complex tasks. This means they must communicate with each other!
In this lesson, we'll explore the main patterns for how your NestJS microservices can send messages and share data effectively.
Sync vs. Async Communication
Understanding the difference between synchronous and asynchronous communication is crucial for microservices:
- Synchronous: The sender waits for an immediate reply. It's like a direct phone call where you expect an answer right away.
- Asynchronous: The sender doesn't wait for a reply. It's like sending an email – you send it and continue with other tasks, expecting a reply later (or not at all).
Both patterns have distinct use cases in a distributed system.
Request-Response Pattern
The Request-Response pattern is a synchronous communication method. One service (the client) sends a request to another service (the server) and pauses its own execution, waiting for a direct response.
- Ideal for operations needing an immediate result.
- Similar to how a typical web client interacts with a REST API.
- Often implemented using HTTP, RPC, or message brokers configured for synchronous replies.
NestJS: Receiving Requests
In NestJS, a microservice listens for incoming requests using the @MessagePattern() decorator. This pattern must match the one sent by the client.
The decorated handler function receives the payload and returns a response. Try running this Product Service microservice:
import { NestFactory } from '@nestjs/core';
import { MicroserviceOptions, Transport } from '@nestjs/microservices';
import { Module, Controller, MessagePattern } from '@nestjs/common';
@Controller()
class ProductController {
@MessagePattern('get_product_details')
getProductDetails(id: string): any {
console.log(`Product Service: Request for ID: ${id}`);
const products = {
'1': { id: '1', name: 'Laptop', price: 1200 },
'2': { id: '2', name: 'Mouse', price: 25 },
};
return products[id] || { id, name: 'Product Not Found', price: 0 };
}
}
@Module({
controllers: [ProductController],
})
class AppModule {}
async function bootstrap() {
const app = await NestFactory.createMicroservice<MicroserviceOptions>(
AppModule,
{
transport: Transport.TCP,
options: { host: '127.0.0.1', port: 8877 },
},
);
await app.listen();
console.log('Product Microservice is listening on port 8877');
}
bootstrap();NestJS: Sending Requests
To send a request to the 'Product Service' (from the previous scene), another microservice or an API Gateway uses a ClientProxy.
The client.send() method dispatches a message with a specific pattern and payload, returning an RxJS Observable that resolves with the response.
This snippet shows how a client service would initiate the request:
// product-client.service.ts in 'Order Service' microservice
import { Injectable, Inject } from '@nestjs/common';
import { ClientProxy } from '@nestjs/microservices';
import { lastValueFrom } from 'rxjs'; // For awaiting observable
@Injectable()
export class ProductClientService {
constructor(@Inject('PRODUCT_SERVICE') private client: ClientProxy) {}
async fetchProduct(productId: string): Promise<any> {
console.log(`Order Service: Fetching product ID: ${productId}`);
// 'get_product_details' must match the pattern in Product Service
const product = await lastValueFrom(
this.client.send('get_product_details', productId),
);
console.log('Received product:', product);
return product;
}
}
// To make this work, 'PRODUCT_SERVICE' needs to be registered
// in an AppModule using ClientsModule.register():
// imports: [
// ClientsModule.register([
// {
// name: 'PRODUCT_SERVICE',
// transport: Transport.TCP,
// options: { host: '127.0.0.1', port: 8877 },
// },
// ]),
// ],When to Use Request-Response
The Request-Response pattern is best when:
- You need an immediate answer from the target service.
- The operation is critical and requires direct feedback (e.g., payment processing, user authentication).
- You are fetching specific data from another service.
- The interaction is a clear client-server relationship.
Be aware that this pattern introduces direct coupling between services.
Event-Based Communication
Event-based communication is an asynchronous pattern that uses a 'publish-subscribe' model. Services don't directly call each other; instead, they publish events to a message broker (like RabbitMQ) when something notable happens.
- A service publishes an event (e.g., 'OrderCreated').
- Other services subscribe to events they are interested in.
- This pattern greatly decouples services, making them more independent.
NestJS: Publishing Events
To publish an event in NestJS, you use the client.emit() method of a ClientProxy. Unlike send(), emit() sends the event and immediately returns, not waiting for a response.
This 'fire-and-forget' approach is ideal for notifying other services about state changes. Run this Order Service that emits an event:
import { NestFactory } from '@nestjs/core';
import { Module, Controller, Post, Body, Inject } from '@nestjs/common';
import { ClientProxy, ClientsModule, Transport } from '@nestjs/microservices';
interface OrderCreatedEvent {
orderId: string;
userId: string;
totalAmount: number;
}
@Controller('orders')
class OrderController {
constructor(@Inject('NOTIFICATION_SERVICE') private client: ClientProxy) {}
@Post()
async createOrder(@Body() orderData: any) {
const orderId = `ORD-${Date.now()}`;
const event: OrderCreatedEvent = {
orderId,
userId: orderData.userId || 'user-123',
totalAmount: orderData.amount || 100,
};
this.client.emit('order_created', event);
console.log(`Order ${orderId} created, 'order_created' event emitted.`);
return { message: 'Order created and event sent', orderId };
}
}
@Module({
imports: [
ClientsModule.register([
{
name: 'NOTIFICATION_SERVICE',
transport: Transport.TCP,
options: { host: '127.0.0.1', port: 8878 },
},
]),
],
controllers: [OrderController],
})
class AppModule {}
async function bootstrap() {
const app = await NestFactory.create(AppModule);
await app.listen(3000);
console.log('Order Service (HTTP) is listening on port 3000');
}
bootstrap();NestJS: Listening to Events
Other microservices can subscribe to events using the @EventPattern() decorator. When an event with a matching pattern is emitted, the decorated method is automatically triggered.
This allows multiple services to react to the same event independently. Run this Notification Service to receive the event:
import { NestFactory } from '@nestjs/core';
import { MicroserviceOptions, Transport } from '@nestjs/microservices';
import { Module, Controller, EventPattern } from '@nestjs/common';
interface OrderCreatedEvent {
orderId: string;
userId: string;
totalAmount: number;
}
@Controller()
class NotificationController {
@EventPattern('order_created')
handleOrderCreated(data: OrderCreatedEvent) {
console.log('Notification Service received OrderCreated event:', data);
console.log(`Sending notification for Order ${data.orderId} to User ${data.userId}`);
}
}
@Module({
controllers: [NotificationController],
})
class AppModule {}
async function bootstrap() {
const app = await NestFactory.createMicroservice<MicroserviceOptions>(
AppModule,
{
transport: Transport.TCP,
options: { host: '127.0.0.1', port: 8878 },
},
);
await app.listen();
console.log('Notification Microservice is listening on port 8878');
}
bootstrap();When to Use Event-Driven
Event-based communication is highly beneficial for:
- Decoupling: Services don't need to know about each other, reducing dependencies.
- Broadcasting: Notifying multiple consumers about a single event (e.g., 'UserRegistered' event).
- Long-running processes: Initiating tasks that don't require an immediate response.
- Resilience: Services can process events when they are available, improving fault tolerance.
It adds complexity but offers great flexibility and scalability.
Communication Patterns Quiz
Consider a scenario where an 'Order Service' needs to inform a 'Shipping Service' that an order is ready to be shipped, but the 'Order Service' doesn't need to wait for the shipping confirmation immediately. Which communication pattern is best suited for this?
Recap: Talking Services
Congratulations! You've learned about the fundamental patterns for inter-service communication in NestJS microservices.
- Request-Response (using
client.send()and@MessagePattern()) is for immediate, direct interactions where a reply is expected. - Event-Based (using
client.emit()and@EventPattern()) is for asynchronous, decoupled communication via events, ideal for notifications and broadcasting.
Choosing the right pattern depends on your specific needs for coupling, responsiveness, and scalability in your distributed system.
Yapay zeka eğitmeniyle TypeScript öğren — ücretsiz
Tarayıcında gerçek kod yaz ve çalıştır, 7/24 yapay zeka eğitmeninden anında yardım al; web'de ya da uygulamada kaldığın yerden devam et.
- Kurslar
- 20
- Dersler
- 76
Sıkça Sorulan Sorular
“Hizmetler Arası İletişim” dersi ücretsiz mi?
Evet — “Hizmetler Arası İletişim” dersin tüm metni burada web'de ücretsiz olarak okunabilir. Etkileşimli olarak pratik yapmak (yerleşik kod editörü ve 7/24 yapay zeka koçu) ve NestJS Enterprise Backend APIs kursunun geri kalanını açmak için CoddyKit PRO'ya yükselt. NestJS Enterprise Backend APIs kursu toplamda 3 dersten oluşur.
“Hizmetler Arası İletişim” dersinde ne öğreneceğim?
Olay tabanlı ve istek-yanıt mekanizmaları dâhil olmak üzere mikro hizmetler arasında etkili iletişim kalıplarını uygulayın. NestJS Enterprise Backend APIs ile uygulamalı kodu tarayıcıda doğrudan çalıştırarak pratik yaparsın ve 7/24 yapay zeka koçu dersi çalışırken sorularını yanıtlar.
NestJS Enterprise Backend APIs öğrenmeye başlamak için deneyim gerekli mi?
Önceden deneyim gerekmez. CoddyKit'te NestJS Enterprise Backend APIs, başlangıçtan ileri seviyeye kadar yapılandırıldığı için buradan başlayabilir veya başından başlayıp kendi hızında ilerleme yapabilirsin. Bu, 3 dersinin 3. dersidir.
“Hizmetler Arası İletişim” dersi ne kadar sürer?
Çoğu CoddyKit dersi yaklaşık 5–10 dakika sürer. Her biri kısa ve etkileşimli olduğu için sabit ilerleme yaparsın ve web ile uygulama arasında tam olarak bıraktığın yerden devam edebilirsin.
Bu NestJS Enterprise Backend APIs dersinde kod yazıp çalıştırabilir miyim?
Evet. Her NestJS Enterprise Backend APIs dersi yerleşik bir kod editörü içerir, bu sayede tarayıcıda gerçek kod yazıp çalıştırabilir ve anlık yapay zeka geri bildirimi alırsın — yerel kurulum gerekli değildir.
Bu kursun tüm dersleri
- NestJS Mikro Hizmetlerine Genel Bakış
- RabbitMQ Entegrasyonu
- Hizmetler Arası İletişim