Overview

Every new capability in iii is added by writing a Worker, never by extending the Engine.

Every new capability in a iii system is added by creating a Worker. A queue, a scheduler, an HTTP edge, a browser tab, an agent, a CRM integration, or a sandbox. Each is a Worker that connects to the Engine and registers Triggers and Functions. The Engine itself never needs to change.

Workers are the services

A Worker is the unit of capability in iii. It is the service. When you need new behaviour, you write a new Worker (or install an existing one from the registry); you do not patch the Engine, add a plugin to it, or fork it. The Engine is a fixed coordinator, it routes invocations between Workers and maintains the live registry of what each Worker provides. Everything that makes a iii system do something useful runs in a Worker.

This is why “add a Worker” is the answer to almost every “how do I add X to iii?” question. If a capability is missing, the gap is filled by a Worker, not by a change to iii itself.

For the mental model behind Workers, Triggers, Functions, and the Engine, see Understanding iii / Overview. To build Workers continue with this section.

What’s in this section

Workers

Connect a Worker to the Engine and deploy it.

Triggers

Declare what causes those Functions to run.

Functions

Register the Functions a Worker contributes.