iii
What is iii?
iii is the easiest way to compose, observe, discover, extend, and react (CODER) to every service in
your stack in real time.
Every backend starts as a project before the first line of business logic. Queues, cron, HTTP,
state, observability, agents, and sandboxes each usually bring their own integration story that
complicates CODER. iii solves all of these concerns with one live system surface.
iii compose --namespace dev --up
iii call -n dev compose::add worker=queue
iii call -n dev compose::add worker=agent
iii call -n dev compose::add worker=<anything>
Each worker joins the live catalog. Every other worker is notified and can call it immediately.
Browse available workers at workers.iii.dev.
That is the agent story too: when a task needs a capability the system does not have, an agent can
add a worker, discover its functions, call them, and trace what happened. Same interface a developer
uses.
Three Primitives
iii is powered by 3 primitives:
Workers are processes that connect to the iii engine and register functions. A TypeScript API
service is a worker. A Python data pipeline is a worker. A Rust microservice is a worker. Any
functionality can be transformed into a worker with a few lines of code. Compose can also add
workers at runtime, so agents and applications can extend the system while it is running.
Functions are units of work with a stable identifier (e.g., content::classify,
orders::validate). A function receives input, does work, and optionally returns output. Functions
exist in workers, and any worker runs any function with iii.call(), wherever it is.
Observers make the system reactive. iii.observe('orders::create', 'alerts::big-order') means:
when orders::create runs, alerts::big-order runs. Every function can be observed, including the
ones workers provide for events: an HTTP request is a call of http::on-request, a cron tick is a
call of cron::on-tick, and a queue message is a call of queue::on-message. iii handles routing,
serialization, and delivery.
By mapping everything a service can do to these three primitives iii creates a development process
that is both effortlessly composable, and completely observable.
What Changes
Before iii:
- New observability tool: uncountable integrations
- New agent harness: separate retry config, separate traces, separate timeouts
- New queue: vendor evaluation, procurement, and weeks of integration
After iii:
- Declare workers in
worker-compose.yaml
- Run them with
iii compose --up
- Done. It is in the system, traceable, and callable.
Platform teams publish workers. Application teams register functions and observe the functions they
react to. Agents use the same catalog and the same function calls.
Extending iii is adding a Compose worker. Composing iii is calling functions. Observing iii is
opening the trace.
Install iii
Install iii:
curl -fsSL https://install.iii.dev/iii/main/install.sh | sh
Add Workers
Declare project workers in worker-compose.yaml, or add them through a running Compose daemon:
iii call -n dev compose::add worker=queue
Browse packages at workers.iii.dev and see the
Compose documentation.
SDKs
| Language | Package | Install |
|---|
| Node.js | iii-sdk | pnpm add iii-sdk or npm install iii-sdk |
| Python | iii-sdk | pip install iii-sdk |
| Rust | iii-sdk | Add to Cargo.toml |
| Go | iii-sdk | go get github.com/iii-hq/iii/sdk/packages/go/iii |
Agent Skills for 3rd party harnesses
If you're using the iii harness then agent skills are automatically available.
If you're using another harness you can install iii's skills via:
npx skills add iii-hq/iii/skills
These cover every iii primitive: HTTP endpoints, queues, cron, state, streams, observers, observable
functions, and more. See skills/ for the full list.
Each worker in iii-hq/workers also ships its own skill. Install
them alongside the worker itself:
npx skills add iii-hq/workers --list # list available worker skills
npx skills add iii-hq/workers --skill database # one worker
npx skills add iii-hq/workers --all # every worker skill
The engine-owned workers (configuration, iii-worker-manager, iii-http-functions, iii-stream,
and iii-sandbox) and the automatically supplied engine functions, telemetry, and observability
workers live in this repo. HTTP, cron, queue, state, pubsub, and bridge are standalone Compose
workers. Install an engine skill with npx skills add iii-hq/iii --full-depth --skill <name>;
standalone workers ship their own skills in iii-hq/workers.
Repository Structure
See CONTRIBUTING.md for workspace dependencies and
CI/CD details.
Resources
Star History
License
The iii is licensed as such:
The engine runtime and the CLI are licensed under the Elastic License 2.0 (ELv2). All SDKs,
documentation, and the website are licensed under the Apache License 2.0.
See CONTRIBUTING.md for additional details.
