File Explorer
Architectural Overview
The project employs a modular monolith architecture centered around a single backend service complemented by a React-based frontend. Key components include a secure document collaboration platform integrating external content embeddings, OAuth 2.0 authorization, shareable content links, and analytics tracking. The frontend utilizes React with state management via React Query and form handling, styled using CSS-in-JS libraries. The backend is built with a Node.js/Express framework, Prisma ORM connected to a PostgreSQL database, and integrated Redis for caching and queuing. Both frontend and backend coexist in a monorepo structure, sharing common utilities and type definitions to ensure consistency and reduce duplication. State management primarily resides within the frontend, while data storage is centralized in PostgreSQL with Redis supporting messaging and cache layers. Environment-specific configurations enable seamless deployment in containerized environments orchestrated via Kubernetes. Unique architectural patterns include fine-grained access controls enforced throughout and server-side rendering for improved SEO and link embedding. This overview is intended for developers, architects, and maintainers seeking a high-level understanding of the system; detailed documentation is available for deeper insights.
Project Components
Frontend
The frontend architecture is based on React, using JavaScript as the primary language. State management is handled via custom hooks and store contexts (useStores), enabling centralized state access and modification. Styling is implemented with styled-components, offering scoped CSS through JavaScript and supporting dynamic styling based on props. The folder structure organizes components by feature and function, with dedicated directories for pages, UI elements, and utilities. Special code organization includes the use of React Router for declarative routing, hooks for lifecycle and side-effect management, and modular component composition to maintain clean separation of concerns and promote reusability across the application.
Backend
The backend is built using the Koa framework in JavaScript, structured as a monolithic application handling various API endpoints with layered middleware. It employs Sequelize as the ORM for PostgreSQL database interactions, configuring connections with managed pools and SSL as appropriate. Core middleware handles request parsing, authentication, and authorization, implementing OAuth 2.0 alongside API key and JWT-based strategies to secure resource access. Authorization is enforced via role and policy checks, with granular controls over document and team-level sharing permissions.
Asynchronous processing and background tasks utilize a queue system (likely Redis-backed), with rate limiting enforced across routes to mitigate abuse. The system integrates error monitoring and tracing through Sentry and Datadog, supporting detailed logging and metrics. The API design follows RESTful principles with clear route controllers managing stateful document retrieval and sharing logic, including support for public shares with embedded analytics.
Custom domain and subdomain resolution middleware enables flexible routing per team branding, while server-side rendering dynamically injects shared content and SEO metadata. Environment configuration is managed via dotenv, with secure handling of credentials and scalable deployment facilitated through Docker and cloud services where applicable. Overall, the backend emphasizes modularity, security, and robust authorization to support collaborative knowledge management.
Shared Code
Shared code between the frontend and backend is organized within a dedicated shared directory in the monorepo, facilitating reuse and consistency across both codebases. This directory contains small utilities, shared React components, the text editor built on ProseMirror, internationalization (i18n) configurations including language-specific translation files, global styles and colors, and common utility methods. By centralizing these common libraries and components, the project avoids duplication and maintains a consistent user experience and functionality across client and server. Both frontend and backend are written in TypeScript, enabling shared type definitions to enhance type safety and developer productivity.
Microservices or Services Overview
| Service Name | Purpose | Key Responsibilities | Communication & Collaboration | Deployment Notes |
|---|---|---|---|---|
| Admin | Development-only service | Access and debug queues via /admin route | Runs independently; primarily for developer access | Run separately; used only in development |
| Web | Primary application server | Hosts main app and API; mandatory for app operation | Collaborates with websockets and collaboration services | At least one instance required; containerized |
| Websockets | Real-time communication handler | Manages real-time frontend-backend communication | Can run on same or separate server from Web service | Can be deployed separately or combined with Web service |
| Worker | Background job processor | Processes queues and async tasks | Works in coordination with other services to handle queued jobs | At least one worker needed; containerized |
| Collaboration | Real-time editing and document update manager | Handles live document collaboration | Communicates with frontend and backend; requires COLLABORATION_URL if running on different domain | May run separately or alongside Web service; configurable via env variable |
Architectural Diagram
Summary and Usage Context
This architectural overview is intended primarily for developers, architects, and maintainers who need a clear understanding of the Outline project’s structure and design decisions. It serves as a foundational guide for onboarding new team members and aligning development efforts across frontend, backend, and shared codebases. Product owners and technical leads may also reference it for high-level insight into component responsibilities and technology choices.
This document fits into the broader documentation ecosystem by complementing detailed API references, functional flow descriptions, deployment guides, and onboarding materials. It helps coordinate workflows by clarifying how modules interact and where key logic resides. For comprehensive understanding, users are encouraged to consult related documents such as backend service architecture, editor usage guides, integration instructions, security policies, and the main README, all of which together support development, deployment, and maintenance activities.