📄 Saga Pattern Guide in Microservices with Node.js

#nodejs #guide #pattern

The Saga pattern addresses this by breaking a transaction into smaller, local transactions handled by different services.

There are 2 approaches to implementing the Saga pattern: Choreography-Based Saga and Orchestration-Based Saga.

— Orchestration-Based Saga: A single orchestrator (arranger) manages all the transactions and directs services to execute local transactions.
— Choreography-Based Saga: All the services that are part of the distributed transaction publish a new event after completing their local transaction.

Choreography-Based Saga approach and a real-world hotel room reservation scenario with 3 microservices: Booking Service, Payment Service, and Notification Service.

— Booking Service: Starts the process by reserving a room. This is the first local transaction. Once successful, it sends a message to the Payment Service to process the payment.
— Payment Service: Receives the message and processes the payment. If the payment is successful, it commits its local transaction and informs the Booking Service and Notification Service.
— Notification Service: On receiving confirmation of successful payment, it sends a booking confirmation email to the user.
— Handling Failures: If the Payment Service encounters an issue (e.g., payment decline), it returns a failure message to the Booking Service. The Booking Service then executes a compensating transaction to cancel the room reservation, ensuring the system returns to its original consistent state.

Prerequisites

— Node.js project with necessary dependencies (express, amqplib, nodemailer, mongoose, dotenv) installed.
— RabbitMQ server running locally or remotely.
— Email server or service for the Notification Service (e.g., Nodemailer with SMTP or an email API service).

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