/iii-getting-started

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

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

Verify it installed:

iii --version

Step 2: Create a Project

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:

cd <your-project>

Step 3: Start the Project

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:

# 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

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

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

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

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

Expected response:

{ "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:

iii trigger -n dev compose::add worker=state
iii trigger -n dev compose::add worker=queue
iii trigger -n dev compose::add worker=image-resize@0.1.2

`compose::add` resolves dependencies, writes exact versions to `worker-compose.yaml`, and restarts the affected project. A local worker can be declared as a `path://` container or added by path.

Install Agent Skills

Get all iii skills for your AI coding agent:

npx skills add iii-hq/iii/skills

Skills teach your agent the top-level iii model: functions, triggers, workers, registry access, SDKs, engine configuration, architecture patterns, and error handling. Worker-backed capabilities live with the worker docs and registry entries.

Adapting This Pattern

• Add more functions to the same worker — each gets its own `registerFunction` + `registerTrigger`

calls

• Use `::` separator for function IDs to namespace them: `orders::create`, `orders::validate`
• Add cron triggers with `{ type: 'cron', config: { expression: '0 0 9 * * * *' } }` (7-field: sec

min hour day month weekday year)

• Add queue triggers with `{ type: 'durable:subscriber', config: { topic: 'my-queue' } }`
• Use `iii.trigger()` to invoke other functions from within a function
• Use `state::get` / `state::set` to persist data across function calls
• Use `iii trigger -n <daemon> compose::add worker=<name>` when the capability already exists in

the worker registry

Recommended Next Steps

After getting your first worker running:

1. **Register functions, triggers, and workers** — See `iii-core-primitives` 2. **Choose the right SDK APIs** — See `iii-sdk-reference` 3. **Configure the engine** — See `iii-engine-config` 4. **Explore backend patterns** — See `iii-architecture-patterns` 5. **Handle failures well** — See `iii-error-handling`

Key Resources

• [Quickstart Guide](https://iii.dev/docs/quickstart)
• [SDK Reference — Node.js](https://iii.dev/docs/api-reference/sdk-node)
• [SDK Reference — Python](https://iii.dev/docs/api-reference/sdk-python)
• [SDK Reference