# Server SDKs Overview

Server-side rendering and streaming for Hypen applications

# Server SDKs

Hypen supports server-side rendering where the WASM engine runs on your server and streams UI patches to clients over WebSocket.

## Architecture

```
┌─────────────────────────────────────────────────────┐
│  Your Server (Bun/Node.js/Go/Kotlin/Swift/Rust)        │
│  • Runs Hypen WASM engine                           │
│  • Manages state and business logic                 │
│  • Streams UI patches over WebSocket                │
└─────────────────────────────────────────────────────┘
                      │ WebSocket
        ┌─────────────┼─────────────┐
        ↓             ↓             ↓
   ┌─────────┐   ┌─────────┐   ┌─────────┐
   │   Web   │   │ Android │   │   iOS   │
   │ Browser │   │   App   │   │   App   │
   └─────────┘   └─────────┘   └─────────┘
```

## How It Works

1. **Client connects** via WebSocket
2. **Server initializes** the WASM engine with your module and UI template
3. **Initial render** — server sends the full UI tree as patches
4. **User interacts** — client sends action messages to the server
5. **State updates** — server processes actions, updates state, and diffs the UI
6. **Patch streaming** — only the changed elements are sent to the client

## Benefits

- **One codebase** — Write once, render on web, Android, and iOS
- **Thin clients** — Clients just apply patches, no WASM needed on device
- **Server-side state** — Easy to persist, secure, and share between users
- **Hot updates** — Change UI without app store updates
- **Session management** — Clients can disconnect and reconnect without losing state

## Available SDKs

| SDK | Language | Status | Package |
|-----|----------|--------|---------|
| [TypeScript](/docs/servers/typescript) | TypeScript/Bun/Node.js | Primary | `@hypen-space/core`, `@hypen-space/server` |
| [Go](/docs/servers/golang) | Go | Stable | `github.com/hypen-lang/hypen-golang` |
| [Kotlin](/docs/servers/kotlin) | Kotlin/JVM | Stable | `space.hypen:hypen-core` |
| [Swift](/docs/servers/swift) | Swift | Stable | `HypenServer` |
| [Rust](/docs/servers/rust) | Rust | Stable | `hypen-server` |

## Quick Start

```typescript
import { app } from "@hypen-space/core";
import { serve } from "@hypen-space/server";

const module = app
  .defineState({ count: 0 })
  .onAction("increment", ({ state }) => {
    state.count++;
  });

await serve({
  module,
  ui: `
    Column {
      Text("Count: @{state.count}")
      Button { Text("+1") }
        .onClick(@actions.increment)
    }
  `,
  port: 3000,
});
```

Connect any Hypen client to `ws://localhost:3000` to render the UI.

## Next Steps

- [TypeScript SDK](/docs/servers/typescript) — Full guide with modules, state, components, sessions, and deployment
- [Go SDK](/docs/servers/golang) — Go server SDK reference
- [Kotlin SDK](/docs/servers/kotlin) — Kotlin/JVM SDK with type-safe DSL and coroutine support
- [Swift SDK](/docs/servers/swift) — Swift SDK with fluent API, typed actions, and Codable state
- [Rust SDK](/docs/servers/rust) — Rust SDK with typed state, serde-based action payloads, and async support
- [Remote App Tutorial](/docs/getting-started/remote-app) — Step-by-step tutorial building a remote app
- [Web Adapter](/docs/adapters/web) — Client-side rendering for browsers