Merancang Saga Berbasis Peristiwa
Rancang alur saga koreografi menggunakan peristiwa untuk memicu tindakan di berbagai layanan mikro.
Merancang Saga Berbasis Peristiwa adalah pelajaran Microservices Communication Patterns (Saga, Circuit Breaker) gratis di CoddyKit. Ini adalah pelajaran 1 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar Microservices Communication Patterns (Saga, Circuit Breaker), dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus Microservices Communication Patterns (Saga, Circuit Breaker) mencakup 4 pelajaran total.
Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.
Event-Driven Saga Design
Welcome! In this lesson, we'll learn how to design the flow of a Choreography Saga. This pattern helps manage complex business transactions that span multiple services.
We'll focus on using events as the primary way services communicate and trigger each other's actions.
Choreography Refresher
Remember Choreography Sagas? In this style, services communicate directly by publishing and subscribing to events.
- No central orchestrator: Services react to events from others.
- Decentralized decisions: Each service decides its next step based on the event it receives.
Our Business Scenario
Let's design a saga for an "Online Order Placement" system. This common scenario involves several steps across different microservices:
- Customer places order.
- Inventory is checked and reserved.
- Payment is processed.
- Order is shipped.
Identifying Core Saga Steps
For our "Order Placement" saga, we can break it down into these main steps, each potentially handled by a different service:
- Order Service: Creates the order.
- Inventory Service: Reserves items.
- Payment Service: Processes payment.
- Shipping Service: Schedules shipment.
Events Drive the Flow
In a choreography saga, each step is initiated by an event. When one service completes its task, it publishes an event.
Other services, interested in that event, subscribe to it and react accordingly. This creates a chain reaction.
Kicking Off the Saga
Every saga needs a starting point. For our "Order Placement," the Order Service initiates the process.
When a customer places an order, the Order Service creates it and publishes an OrderCreatedEvent.
Inventory Reacts to Order
The Inventory Service subscribes to OrderCreatedEvent. Upon receiving it, it attempts to reserve the items for the order.
After processing, it publishes either an InventoryReservedEvent or an InventoryFailedEvent.
class OrderCreatedEvent {
String orderId;
String customerId;
// ... item details
}
class InventoryService {
public void handleOrderCreated(OrderCreatedEvent event) {
System.out.println("Inventory Service: Received OrderCreatedEvent for " + event.orderId);
// Logic to reserve items...
boolean success = true; // Assume success for now
if (success) {
System.out.println("Inventory Service: Items reserved. Publishing InventoryReservedEvent.");
// In a real system, publish InventoryReservedEvent
} else {
System.out.println("Inventory Service: Inventory failed. Publishing InventoryFailedEvent.");
// In a real system, publish InventoryFailedEvent
}
}
}
public class Main {
public static void main(String[] args) {
InventoryService inventory = new InventoryService();
OrderCreatedEvent newOrder = new OrderCreatedEvent();
newOrder.orderId = "ORD123";
newOrder.customerId = "CUST456";
inventory.handleOrderCreated(newOrder);
}
}Payment Reacts to Inventory
The Payment Service subscribes to InventoryReservedEvent. This means payment only proceeds if inventory is successfully reserved.
It processes the payment and then publishes either a PaymentProcessedEvent or a PaymentFailedEvent.
Shipping Reacts to Payment
Finally, the Shipping Service subscribes to PaymentProcessedEvent. It schedules the shipment only after payment is confirmed.
It then publishes an OrderShippedEvent to complete the main saga flow.
Planning for Rollbacks
What if a step fails? For example, if payment fails after inventory is reserved? In a choreography saga, we use compensation events.
The Payment Service would publish a PaymentFailedEvent. The Inventory Service would subscribe to this event and publish an InventoryReleasedEvent to undo its previous action.
Saga Flow Check
Consider our Order Placement saga. What is the correct sequence of events if the entire process is successful?
Recap: Designing Event Flows
We've learned how to design a choreography saga by breaking down a business transaction into steps.
- Each step publishes an event to trigger the next.
- We identified the initial event and subsequent events for a successful flow.
- We also briefly considered how compensation events are used to handle failures.
Next, we'll explore how message brokers facilitate this communication!
Pertanyaan yang Sering Diajukan
Apakah pelajaran “Merancang Saga Berbasis Peristiwa” gratis?
Ya — teks lengkap “Merancang Saga Berbasis Peristiwa” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus Microservices Communication Patterns (Saga, Circuit Breaker), upgrade ke CoddyKit PRO. Kursus Microservices Communication Patterns (Saga, Circuit Breaker) mencakup 4 pelajaran total.
Apa yang akan aku pelajari di “Merancang Saga Berbasis Peristiwa”?
Rancang alur saga koreografi menggunakan peristiwa untuk memicu tindakan di berbagai layanan mikro. Kamu berlatih Microservices Communication Patterns (Saga, Circuit Breaker) dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.
Apakah aku perlu pengalaman untuk memulai Microservices Communication Patterns (Saga, Circuit Breaker)?
Tidak diperlukan pengalaman sebelumnya. Microservices Communication Patterns (Saga, Circuit Breaker) di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 1 dari 4.
Berapa lama pelajaran “Merancang Saga Berbasis Peristiwa” memakan waktu?
Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.
Bisakah aku menulis dan menjalankan kode dalam pelajaran Microservices Communication Patterns (Saga, Circuit Breaker) ini?
Ya. Setiap pelajaran Microservices Communication Patterns (Saga, Circuit Breaker) menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.
Semua pelajaran dalam kursus ini
- Merancang Saga Berbasis Peristiwa
- Bus Peristiwa dan Perantara Pesan
- Menangani Kompensasi dengan Peristiwa
- Membangun Konsumen Peristiwa Idempoten