AI Agent Skill HUB

nestjs-real-time

Implement WebSocket gateways with Socket.io and Server-Sent Events endpoints in NestJS. Use when building chat features, live feeds, or choosing between WebSocket and SSE for real-time communication. (triggers: **/*.gateway.ts, **/*.controller.ts, WebSocketGateway, SubscribeMessage, Sse, Socket.io)

385 stars
byHoangNguyen0403
View on GitHubInstallation ↓

Best use case

nestjs-real-time is best used when you need a repeatable AI agent workflow instead of a one-off prompt.

Implement WebSocket gateways with Socket.io and Server-Sent Events endpoints in NestJS. Use when building chat features, live feeds, or choosing between WebSocket and SSE for real-time communication. (triggers: **/*.gateway.ts, **/*.controller.ts, WebSocketGateway, SubscribeMessage, Sse, Socket.io)

Teams using nestjs-real-time should expect a more consistent output, faster repeated execution, less prompt rewriting.

When to use this skill

  • You want a reusable workflow that can be run more than once with consistent structure.

When not to use this skill

  • You only need a quick one-off answer and do not need a reusable workflow.
  • You cannot install or maintain the underlying files, dependencies, or repository context.

Installation

Claude Code / Cursor / Codex

$curl -o ~/.claude/skills/nestjs-real-time/SKILL.md --create-dirs "https://raw.githubusercontent.com/HoangNguyen0403/agent-skills-standard/main/skills/nestjs/nestjs-real-time/SKILL.md"

Manual Installation

  1. Download SKILL.md from GitHub
  2. Place it in .claude/skills/nestjs-real-time/SKILL.md inside your project
  3. Restart your AI agent — it will auto-discover the skill

How nestjs-real-time Compares

Feature / Agentnestjs-real-timeStandard Approach
Platform SupportNot specifiedLimited / Varies
Context Awareness High Baseline
Installation ComplexityUnknownN/A

Frequently Asked Questions

What does this skill do?

Implement WebSocket gateways with Socket.io and Server-Sent Events endpoints in NestJS. Use when building chat features, live feeds, or choosing between WebSocket and SSE for real-time communication. (triggers: **/*.gateway.ts, **/*.controller.ts, WebSocketGateway, SubscribeMessage, Sse, Socket.io)

Where can I find the source code?

You can find the source code on GitHub using the link provided at the top of the page.

SKILL.md Source

# Real-Time & WebSockets

## **Priority: P1 (OPERATIONAL)**

WebSocket and real-time communication patterns with NestJS.

## Workflow: Add Real-Time Feature

1. **Choose protocol** — WebSocket for bi-directional (chat, collab); SSE for uni-directional (feeds, notifications).
2. **Implement gateway or SSE** — Create a `@WebSocketGateway()` or `@Sse()` controller.
3. **Add auth** — Validate JWT in `handleConnection()` for WebSocket; use standard guards for SSE.
4. **Scale** — Add `@socket.io/redis-adapter` for multi-pod WebSocket; use HTTP/2 for SSE.
5. **Test connections** — Verify WebSocket handshake auth rejects invalid tokens; confirm SSE streams data.

## SSE Endpoint Example

See [implementation examples](references/example.md)

## WebSocket Gateway with Auth Example

See [implementation examples](references/example.md)

## Protocol Selection

- **WebSockets (Bi-directional)**: Use for Chat, Multiplayer Games, Collaborative Editing.
  - _High Complexity_: Requires custom scaling (Redis Adapter) and sticky sessions (sometimes).
- **Server-Sent Events (SSE) (Uni-directional)**: Use for Notifications, Live Feeds, Tickers, CI Log streaming.
  - _Low Complexity_: Standard HTTP. Works with standard Load Balancers. Easy to secure.
  - _NestJS_: Use `@Sse('route')` returning `Observable<MessageEvent>`.
- **Long Polling**: Use **only** as a fallback or for extremely low-frequency updates (e.g., job status check every 10m).
  - _Impact_: High header overhead. Blocks threads if not handled carefully.

## WebSockets Implementation

- **Socket.io**: Default choice. Features "Rooms", "Namespaces", and automatic reconnection. Heavy protocol.
- **Fastify/WS**: Use `ws` adapter if performance is critical (e.g., high-frequency trading updates) and you don't need "Rooms" logic.

## Scaling (Critical)

- **WebSockets**: In K8s, a client connects to Pod A. If Pod B emits an event, the client won't receive it.
  - **Solution**: **Redis Adapter** (`@socket.io/redis-adapter`). Every pod publishes to Redis; Redis distributes to all other pods.
- **SSE**: Stateless. No special adapter needed, but be aware of **Connection Limits** (6 concurrent connections per domain in HTTP/1.1; virtually unlimited in HTTP/2).
  - **Rule**: Must use **HTTP/2** for SSE at scale.

## Security

- **Handshake Auth**: Standard HTTP Guards don't trigger on Ws connection efficiently.
  - **Pattern**: Validate JWT during the `handleConnection()` lifecycle method. Disconnect immediately if invalid.
- **Rate Limiting**: Sockets are expensive. Apply strict throttling on "Message" events to prevent flooding.

## Architecture

- **Gateway != Service**: The `WebSocketGateway` should **only** handle client comms (Join Room, Ack message).
  - **Rule**: Delegate business logic to a Service or Command Bus.
- **Events**: Use `AsyncApi` or `SocketApi` decorators (from community packages) to document WS events similarly to OpenAPI.


## Anti-Patterns

- **No HTTP guards for WebSocket auth**: Validate JWT in `handleConnection()`; HTTP guards don't trigger on WS.
- **No WebSocket at scale without Redis adapter**: Without `@socket.io/redis-adapter`, cross-pod events are lost.
- **No SSE over HTTP/1.1 at scale**: Use HTTP/2 to avoid the 6-connection-per-domain browser limit.

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