Self-Contained Systems

Self-Contained Systems is an architectural pattern where an application is structured as a suite of independently deployable services, each with its own database and logic. These systems are designed to be loosely coupled, communicating with each other via well-defined APIs, but without sharing databases or internal state. This approach promotes autonomy, allowing teams to develop, deploy, and scale individual systems independently.

The core principle is to minimize dependencies between components. Each system is responsible for its own data consistency and availability. This contrasts with monolithic architectures or shared-database approaches, where changes in one part of the system can have cascading effects on others. This pattern is often used in microservice architectures, but can be applied at a coarser granularity as well.

Usage

This pattern is commonly used in:

• Microservice Architectures: The most prevalent use case, where each microservice embodies a self-contained system.
• Large-Scale Applications: Breaking down a large application into smaller, manageable systems improves maintainability and scalability.
• Organizations with Multiple Teams: Allows teams to own and operate their systems independently, fostering agility and ownership.
• Systems Requiring High Availability: Isolating failures within a single system prevents them from impacting the entire application.
• Event-Driven Architectures: Systems can react to events published by other systems without direct coupling.

Examples

• Netflix: Netflix famously adopted a microservice architecture built on self-contained systems. Each component, like the recommendation engine, video encoding pipeline, or user account management, operates as an independent service with its own data store. This allows Netflix to scale individual features based on demand and deploy updates without disrupting the entire platform.
• Amazon: Amazon’s e-commerce platform is composed of numerous self-contained systems. For example, the ordering system, the payment processing system, and the shipping system each have their own databases and logic. This separation allows Amazon to handle massive transaction volumes and maintain high availability, even during peak shopping seasons.
• Shopify: Shopify utilizes self-contained systems for different aspects of its platform, such as the storefront, order management, and payment gateway integrations. This allows for independent scaling and development of each feature, catering to the diverse needs of its merchants.