iii-getting-started

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---
name: iii-getting-started
description: >-
  Install the iii engine, set up your first worker, and get a working backend running. Use when a
  user wants to start a new iii project, install the SDK, or needs help with initial setup and
  configuration.
---

# Getting Started with iii

iii replaces your API framework, task queue, cron scheduler, pub/sub, state store, and observability
pipeline with a single engine and three primitives: **Function**, **Trigger**, **Worker**.

## Step 1: Install the Engine

```bash
curl -fsSL https://install.iii.dev/iii/main/install.sh | sh
```

Verify it installed:

```bash
iii --version
```

## Step 2: Create a Project

```bash
iii create
```

Follow the interactive prompts to select a template and language. The default quickstart template
includes TypeScript, Python, and Rust workers.

Then change into the project directory you chose at the prompt:

```bash
cd <your-project>
```

## Step 3: Start the Project

```bash
iii compose --namespace dev --up --file worker-compose.yaml
```

The file's `engine:` section starts the engine; `containers:` starts project workers. The engine
commonly listens on `ws://localhost:49134`. Keep this foreground supervisor running.

## Step 4: Install the SDK

Pick your language:

```bash
# TypeScript / Node.js
pnpm add iii-sdk @iii-dev/helpers

# Python
pip install iii-sdk iii-helpers

# Rust
cargo add iii-sdk iii-helpers
```

## Step 5: Write Your First Worker

### TypeScript

```typescript
import { registerWorker, TriggerAction } from "iii-sdk";
import { Logger } from "@iii-dev/helpers/observability";

const iii = registerWorker(process.env.III_URL ?? "ws://localhost:49134");

iii.registerFunction(
  "hello::greet",
  async (input) => {
    const logger = new Logger();
    const name = input?.name ?? "world";
    logger.info("Greeting user", { name });
    return { message: `Hello, ${name}!` };
  },
  { description: "Greet a user by name" },
);

iii.registerTrigger({
  type: "http",
  function_id: "hello::greet",
  config: { api_path: "/hello", http_method: "POST" },
});
```

### Python

```python
from iii import register_worker, InitOptions
from iii_helpers.observability import Logger

iii = register_worker(address="ws://localhost:49134", options=InitOptions(worker_name="hello-worker"))

def greet(data):
    logger = Logger()
    name = data.get("name", "world") if isinstance(data, dict) else "world"
    logger.info("Greeting user", {"name": name})
    return {"message": f"Hello, {name}!"}

iii.register_function("hello::greet", greet, description="Greet a user by name")
iii.register_trigger({"type": "http", "function_id": "hello::greet", "config": {"api_path": "/hello", "http_method": "POST"}})
```

### Rust

```rust
use iii_sdk::{register_worker, InitOptions, RegisterFunction};
use iii_sdk::protocol::RegisterTriggerInput;
use iii_helpers::observability::Logger;
use serde_json::json;

let iii = register_worker("ws://127.0.0.1:49134", InitOptions::default());

iii.register_function(
    RegisterFunction::new("hello::greet", |input: serde_json::Value| -> Result<serde_json::Value, String> {
        let logger = Logger::new();
        let name = input["name"].as_str().unwrap_or("world");
        logger.info("Greeting user", Some(json!({ "name": name })));
        Ok(json!({ "message": format!("Hello, {}!", name) }))
    }).description("Greet a user by name"),
);

iii.register_trigger(RegisterTriggerInput {
    trigger_type: "http".into(),
    function_id: "hello::greet".into(),
    config: json!({ "api_path": "/hello", "http_method": "POST" }),
    metadata: None,
})?;
```

## Step 6: Test It

```bash
curl -X POST http://localhost:3111/hello \
  -H "Content-Type: application/json" \
  -d '{"name": "iii"}'
```

Expected response:

```json
{ "message": "Hello, iii!" }
```

## Add Existing Workers

To add a capability that already exists, browse `https://workers.iii.dev/` and add it through the
running Compose daemon:

```bash
iii trigger -n dev compose::add worker=