Architecture
Elixir and Phoenix for Real-Time
Elixir and Phoenix are purpose-built for real-time, concurrent applications. Master the BEAM VM, OTP framework, Phoenix Channels, and the actor model for building systems that handle millions of concurrent connections.
- Concurrency β Lightweight processes (millions of lightweight processes)
- Fault Tolerance β "Let it crash" philosophy with supervisors
- Real-Time β WebSocket channels out of the box
Elixir is what you reach for when real-time is not optional.
The BEAM VM
Process Model
OTP Framework
| OTP Behaviour | Purpose |
|---|---|
| GenServer | Generic server with synchronous and asynchronous calls |
| Supervisor | Monitors child processes, restarts on failure |
| Application | Bundles components and manages lifecycle |
| Agent | Simple state management across processes |
| Task | Asynchronous one-shot tasks |
Supervisor Trees
| Restart Strategy | Behavior |
|---|---|
| one_for_one | Restart only the failed child |
| one_for_all | Restart all children if any fails |
| rest_for_one | Restart failed child and all children started after it |
Phoenix Channels
| Component | Purpose |
|---|---|
| Socket | WebSocket connection handler |
| Channel | Topic-based message handling |
| Topic | Namespace for messages (e.g., "room:lobby") |
| Push | Server β client message |
| Broadcast | Server β all subscribers on a topic |
Concurrency at Scale
Practice Exercises
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Process Design: Design a chat application using Elixir processes. How do you model rooms, users, and message routing?
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Supervisor Strategy: Design the supervisor tree for a real-time notification system with WebSocket connections, message queues, and database connections.
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Phoenix Channel: Build a real-time collaborative document editor using Phoenix Channels. How do you handle conflict resolution?
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Performance Analysis: Compare the memory and CPU usage of handling 1M concurrent WebSocket connections in Elixir vs Node.js.
What to Learn Next
-> WebSockets and Real-Time WebSocket protocols, connection management, and scaling patterns.
-> gRPC and Protobuf High-performance RPC with protocol buffers.
-> Message Queues Async processing, event-driven architecture, and pub/sub patterns.
-> Event-Driven Architecture Event sourcing, CQRS, and message-driven systems.
-> Chat System Design Designing real-time chat systems at scale.
-> Realtime Analytics Design Designing real-time analytics dashboards.