export const metadata = {
  title: `${pageNumber} Medusa's Architecture`,
}

# {metadata.title}

In this chapter, you'll learn about the architectural layers in Medusa.

## HTTP, Workflow, and Module Layers

Medusa is a headless commerce platform. So, storefronts, admin dashboards, and other clients consume Medusa's functionalities through its API routes.

In a common Medusa application, requests go through four layers in the stack. In order of entry, those are:

1. API Routes (HTTP): Our API Routes are the typical entry point.
2. Workflows: API Routes consume workflows that hold the opinionated business logic of your application.
3. Modules: Workflows use domain-specific modules for resource management.
3. Data store: Modules query the underlying datastore, which is a PostgreSQL database in common cases.

![Diagram illustrating the HTTP layer](https://res.cloudinary.com/dza7lstvk/image/upload/v1727175296/Medusa%20Book/http-layer_sroafr.jpg)

---

## Database Layer

The Medusa application injects into each module a connection to the configured PostgreSQL database.

Modules use that connection to read and write data to the database.

![Diagram illustrating the database layer](https://res.cloudinary.com/dza7lstvk/image/upload/v1727175379/Medusa%20Book/db-layer_pi7tix.jpg)

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## Service Integrations

Third-party services are integrated through commerce and architectural modules.

You also create custom third-party integrations through a custom module.

### Commerce Modules

Commerce modules integrate third-party services relevant for commerce or user-facing features. For example, you integrate Stripe through a payment module provider.

![Diagram illustrating the commerce modules integration to third-party services](https://res.cloudinary.com/dza7lstvk/image/upload/v1727175357/Medusa%20Book/service-commerce_qcbdsl.jpg)

### Architectural Modules

Architectural modules integrate third-party services and systems for architectural features. For example, you integrate Redis as a pub/sub service to send events, or SendGrid to send notifications.

![Diagram illustrating the architectural modules integration to third-party services and systems](https://res.cloudinary.com/dza7lstvk/image/upload/v1727175342/Medusa%20Book/service-arch_ozvryw.jpg)

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## Full Diagram of Medusa's Architecture

The following diagram illustrates Medusa's architecture over the three layers.

![Full diagram illustrating Medusa's architecture](https://res.cloudinary.com/dza7lstvk/image/upload/v1727174897/Medusa%20Book/architectural-diagram-full.jpg)