# Saga

> Saga pattern for distributed transactions. Use for microservices transactions.

- Skill: `g1joshi/saga` (Agent Skill)
- Install (CLI): `npx skillmds@latest add g1joshi/saga`
- Raw SKILL.md: https://api.skillmd.com/api/skills/g1joshi/saga/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: G1Joshi (https://skillmd.com/u/g1joshi)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/g1joshi/saga

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# Saga Pattern

The Saga pattern manages data consistency across microservices in distributed transaction scenarios. A Saga is a sequence of local transactions. Each local transaction updates the database and publishes a message or event to trigger the next local transaction in the saga.

## When to Use

- **Distributed Transactions**: e.g., "Book Flight" + "Book Hotel" + "Charge Card".
- Long-running processes where you can't hold a DB lock.
- Ensuring eventual consistency across Services A, B, and C.

## Core Concepts

### Compensating Transactions

If a step fails (e.g., Card Declined), the Saga must execute **compensating transactions** to undo the changes made by the preceding steps (e.g., "Cancel Hotel", "Cancel Flight").

### Choreography

Each service listens to events and decides what to do.

- Order Service -> `OrderCreated`
- Inventory Service -> listends to `OrderCreated` -> does work -> `InventoryReserved`

### Orchestration

A central coordinator (Orchestrator) tells each service what to do.

- Orchestrator -> Call Order Service
- Orchestrator -> Call Inventory Service
- Orchestrator -> Handle failure -> Call Compensation.

## Best Practices

**Do**:

- Prefer **Orchestration** for complex sagas (easier to visualize and trace).
- Ensure all steps are **Idempotent**.
- Design for failure (Everything that can fail, will fail).

**Don't**:

- Don't rely on synchronous HTTP calls for Sagas (What if the network drops in the middle?). Use Message Queues or Persistent Orchestrators (Temporal).

## Tools

- **Temporal.io**: Workflow engine for code-based orchestration.
- **MassTransit** (C#): Built-in Saga state machines.

## References

- [Microservices.io - Saga](https://microservices.io/patterns/data/saga.html)
- [Temporal](https://temporal.io/)