Everything is a Worker

Why we renamed modules to workers and how to migrate.

Why this change

iii is built on three primitives: Workers, Functions, and Triggers. Every concept in the system maps to one of these:

• Workers are long-running processes that connect to the engine and provide capabilities — HTTP serving, queue processing, cron scheduling, state management, stream handling, and anything else the engine needs to operate.
• Functions are units of work. A worker registers functions, and any other worker (or the engine itself) can invoke them by ID.
• Triggers are the rules that cause functions to fire — an HTTP request, a cron schedule, a queue message, a state change.

Before this release, the engine-internal components that provide capabilities (HTTP, queues, cron, etc.) were called “modules”. Meanwhile, the remote SDK processes that register functions were called “workers”. This created a confusing split: two different names for things that serve the same role — connecting to the engine and doing work.

Modules are workers. They run alongside the engine, register functions, react to triggers, and provide capabilities to the rest of the system. The only difference was the name.

By renaming modules to workers, every component in the system uses the same vocabulary. The engine config lists workers:. The SDK connects workers. The docs describe workers. There is one concept, one name, and one mental model.

The previous Worker struct (representing a connected SDK runtime over WebSocket) has been renamed to WorkerConnection to avoid collision.

---

What changed

Config YAML

The top-level modules: key is now workers:, and each entry uses name: with a short identifier instead of class: with a Rust-style path.

# Before
modules:
  - class: modules::stream::StreamModule
    config:
      port: 3112

# After
workers:
  - name: iii-stream
    config:
      port: 3112

The modules: key is still accepted for backward compatibility, but workers: is the canonical form going forward.

Worker name mapping

Old class: value	New name: value
modules::worker::WorkerModule	iii-worker-manager
modules::stream::StreamModule	iii-stream
modules::state::StateModule	iii-state
modules::api::RestApiModule	iii-http
modules::pubsub::PubSubModule	iii-pubsub
modules::observability::OtelModule	iii-observability
modules::queue::QueueModule	iii-queue
modules::http_functions::HttpFunctionsModule	iii-http-functions
modules::cron::CronModule	iii-cron
modules::shell::ExecModule	iii-exec
modules::bridge_client::BridgeClientModule	iii-bridge

Adapter name mapping

Adapter entries inside config.adapter also switched from class: to name: with short identifiers:

Old adapter class:	New adapter name:
modules::stream::adapters::KvStore	kv
modules::stream::adapters::RedisAdapter	redis
modules::stream::adapters::Bridge	bridge
modules::state::adapters::KvStore	kv
modules::state::adapters::RedisAdapter	redis
modules::state::adapters::Bridge	bridge
modules::pubsub::LocalAdapter	local
modules::pubsub::RedisAdapter	redis
modules::queue::BuiltinQueueAdapter	builtin
modules::queue::RedisAdapter	redis
modules::queue::RabbitMQAdapter	rabbitmq
modules::queue::adapters::Bridge	bridge
modules::cron::KvCronAdapter	kv
modules::cron::RedisCronAdapter	redis

Full config example

Before

modules:
  - class: modules::stream::StreamModule
    config:
      port: 3112
      adapter:
        class: modules::stream::adapters::KvStore
        config:
          store_method: file_based
          file_path: ./data/stream_store

  - class: modules::state::StateModule
    config:
      adapter:
        class: modules::state::adapters::KvStore
        config:
          store_method: file_based
          file_path: ./data/state_store.db

  - class: modules::api::RestApiModule
    config:
      port: 3111

  - class: modules::observability::OtelModule
    config:
      enabled: true

  - class: modules::queue::QueueModule
    config:
      adapter:
        class: modules::queue::BuiltinQueueAdapter

  - class: modules::pubsub::PubSubModule
    config:
      adapter:
        class: modules::pubsub::LocalAdapter

  - class: modules::cron::CronModule
    config:
      adapter:
        class: modules::cron::KvCronAdapter

After

workers:
  - name: iii-stream
    config:
      port: 3112
      adapter:
        name: kv
        config:
          store_method: file_based
          file_path: ./data/stream_store

  - name: iii-state
    config:
      adapter:
        name: kv
        config:
          store_method: file_based
          file_path: ./data/state_store.db

  - name: iii-http
    config:
      port: 3111

  - name: iii-observability
    config:
      enabled: true

  - name: iii-queue
    config:
      adapter:
        name: builtin

  - name: iii-pubsub
    config:
      adapter:
        name: local

  - name: iii-cron
    config:
      adapter:
        name: kv

---

Rust API

Crate module path

The modules Rust module has been renamed to workers, and the trait definition file moved from module.rs to traits.rs.

// Before
use iii::modules::config::EngineBuilder;
use iii::modules::module::Module;
use iii::modules::registry::ModuleRegistration;

// After
use iii::workers::config::EngineBuilder;  // also re-exported as iii::EngineBuilder
use iii::workers::traits::Worker;
use iii::workers::registry::WorkerRegistration;

Trait renames

Before	After
trait Module	trait Worker
trait ConfigurableModule	trait ConfigurableWorker
Module::make_module()	Worker::make_worker()
Module::create() -> Box<dyn Module>	Worker::create() -> Box<dyn Worker>
ConfigurableModule::DEFAULT_ADAPTER_CLASS	ConfigurableWorker::DEFAULT_ADAPTER_NAME
ConfigurableModule::default_adapter_class()	ConfigurableWorker::default_adapter_name()
ConfigurableModule::adapter_class_from_config()	ConfigurableWorker::adapter_name_from_config()

Type alias and struct renames

Before	After
ModuleFuture	WorkerFuture
ModuleFactory	WorkerFactory
ModuleInfo	WorkerInfo
ModuleRegistry	WorkerRegistry
ModuleEntry	WorkerEntry
ModuleRegistration	WorkerRegistration

Macro renames

Before	After
register_module!(class, Type, ...)	register_worker!(name, Type, ...)

EngineBuilder API

Before	After
EngineBuilder::add_module(class, config)	EngineBuilder::add_worker(name, config)
EngineBuilder::register_module::<M>(class)	EngineBuilder::register_worker::<M>(name)

Implementation struct renames

Before	After
WorkerModule	WorkerManager
StreamCoreModule	StreamWorker
StateCoreModule	StateWorker
RestApiCoreModule	HttpWorker
PubSubCoreModule	PubSubWorker
OtelModule	ObservabilityWorker
QueueCoreModule	QueueWorker
HttpFunctionsModule	HttpFunctionsWorker
CronCoreModule	CronWorker
ExecCoreModule	ExecWorker
BridgeClientModule	BridgeClientWorker
TelemetryModule	TelemetryWorker
EngineFunctionsModule	EngineFunctionsWorker
ExternalModule	ExternalWorker

WorkerConnection (was Worker)

The Worker struct that represented a connected remote SDK runtime has been renamed to WorkerConnection and moved to a separate module.

Before	After
crate::workers::Worker	crate::worker_connections::WorkerConnection
crate::workers::WorkerRegistry	crate::worker_connections::WorkerConnectionRegistry
crate::workers::WorkerStatus	crate::worker_connections::WorkerConnectionStatus
crate::workers::WorkerTelemetryMeta	crate::worker_connections::WorkerConnectionTelemetryMeta

---

Migration examples

Custom worker

Before

use iii::modules::module::Module;

pub struct MyModule { /* ... */ }

#[async_trait]
impl Module for MyModule {
    fn name(&self) -> &'static str { "MyModule" }
    async fn create(engine: Arc<Engine>, config: Option<Value>) -> anyhow::Result<Box<dyn Module>> {
        Ok(Box::new(MyModule { /* ... */ }))
    }
    async fn initialize(&self) -> anyhow::Result<()> { Ok(()) }
}

iii::register_module!("my::custom::Module", MyModule, enabled_by_default = true);

After

use iii::workers::traits::Worker;

pub struct MyWorker { /* ... */ }

#[async_trait]
impl Worker for MyWorker {
    fn name(&self) -> &'static str { "MyWorker" }
    async fn create(engine: Arc<Engine>, config: Option<Value>) -> anyhow::Result<Box<dyn Worker>> {
        Ok(Box::new(MyWorker { /* ... */ }))
    }
    async fn initialize(&self) -> anyhow::Result<()> { Ok(()) }
}

iii::register_worker!("iii-my-custom", MyWorker, enabled_by_default = true);

Custom adapter

Before

iii::register_adapter!(
    <MyAdapterRegistration>
    "modules::my_worker::MyAdapter",
    make_adapter
);

After

iii::register_adapter!(
    <MyAdapterRegistration>
    name: "my-adapter",
    make_adapter
);

---

Migration checklist

• Rename modules: to workers: in all config YAML files
• Replace class: with name: using the new short identifiers (see tables above)
• Replace adapter class: with name: using short identifiers (kv, redis, builtin, etc.)
• Update Rust imports from iii::modules:: to iii::workers::
• Update iii::modules::module::Module to iii::workers::traits::Worker
• Replace register_module! with register_worker!
• Replace add_module() / register_module() on EngineBuilder with add_worker() / register_worker()
• Rename any *Module / *CoreModule struct references to the new *Worker / *Manager names
• Update crate::workers::Worker references to crate::worker_connections::WorkerConnection