In complex distributed systems, failures are inevitable. When processes span multiple services or systems, traditional database transactions (with ACID properties) become impractical. This is where the SAGA pattern comes into play—offering a robust way to manage failures in distributed transactions by using Action and Compensating Action pairs for each step in the integration process.

What is the SAGA Pattern?

The SAGA pattern is a microservice architecture pattern used to ensure data consistency across services without relying on distributed transactions. Instead of a single, atomic transaction, the SAGA pattern breaks a process into a series of local transactions. Each local transaction updates a service and publishes an event or triggers the next step.

If one step fails, the system runs a compensating transaction to undo the changes made by the preceding steps.

Components of the SAGA Pattern

1. Action (T)

Each step in a SAGA workflow performs an action, such as:

• Creating a record in a database
• Sending a confirmation message
• Executing a payment or API call

2. Compensating Action (C)

If something goes wrong in a subsequent step, the compensating action undoes the previous action:

• Delete the created record
• Send a cancellation message
• Refund the payment

This ensures that the system can revert to a consistent state even if the full process cannot be completed.

Example Use Case: Order Processing

Consider an e-commerce order processing service that includes:

1. Reserving inventory