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Installation

cargo add iii-sdk

Initialization

register_worker

Create and return a connected SDK instance. The WebSocket connection is established automatically in a dedicated background thread with its own tokio runtime. Call IIIClient::shutdown before the end of main to cleanly stop the connection and join the background thread. In Rust the process exits when main returns, terminating all threads, so shutdown() must be called while main is still running. Signature
register_worker(address: &str, options: InitOptions) -> IIIClient

Parameters

NameTypeRequiredDescription
address&strYesWebSocket URL of the III engine (e.g. ws://localhost:49134).
optionsInitOptionsYesConfiguration for worker metadata and OTel.

Example

use iii_sdk::{register_worker, InitOptions};

let worker = register_worker("ws://localhost:49134", InitOptions::default());
// register functions, handle events, etc.
worker.shutdown(); // cleanly stops the connection thread

Methods

register_trigger

Bind a trigger configuration to a registered function. Signature
register_trigger(input: RegisterTriggerInput) -> Result<Trigger, Error>

Parameters

NameTypeRequiredDescription
inputRegisterTriggerInputYesTrigger registration input with trigger_type, function_id, and config.

Example

let trigger = worker.register_trigger(RegisterTriggerInput {
    trigger_type: "http".to_string(),
    function_id: "greet".to_string(),
    config: json!({ "api_path": "/greet", "http_method": "GET" }),
    metadata: None,
})?;
// Later...
trigger.unregister();

register_function

Register a function with the engine. Argument order matches the Node and Python SDKs: (id, registration). Signature
register_function(id: impl Into<String>, registration: RegisterFunction) -> FunctionRef

Parameters

NameTypeRequiredDescription
idimpl Into<String>Yes-
registrationRegisterFunctionYes-

Example

use iii_sdk::{register_worker, InitOptions, Error, RegisterFunction};
use serde::{Deserialize, Serialize};
use schemars::JsonSchema;

#[derive(Deserialize, JsonSchema)]
struct Input { name: String }
#[derive(Serialize, JsonSchema)]
struct Output { message: String }

async fn greet(input: Input) -> Result<Output, Error> {
    Ok(Output { message: format!("Hello, {}!", input.name) })
}

let worker = register_worker("ws://localhost:49134", InitOptions::default());
worker.register_function(
    "greetings::greet",
    RegisterFunction::new_async(greet).description("Greets a user"),
);

trigger

Invoke a remote function. The routing behavior depends on the action field of the request:
  • No action: synchronous — waits for the function to return.
  • TriggerAction::Enqueue - async via named queue.
  • TriggerAction::Void: fire-and-forget.
Signature
async trigger(request: impl Into<TriggerRequest>) -> Result<Value, Error>

Parameters

NameTypeRequiredDescription
requestimpl Into<TriggerRequest>Yes-

Example

// Synchronous
let result = worker.trigger(TriggerRequest {
    function_id: "greet".to_string(),
    payload: json!({"name": "World"}),
    action: None,
    timeout_ms: None,
}).await?;

// Fire-and-forget
worker.trigger(TriggerRequest {
    function_id: "notify".to_string(),
    payload: json!({}),
    action: Some(TriggerAction::Void),
    timeout_ms: None,
}).await?;

// Enqueue
let receipt = worker.trigger(TriggerRequest {
    function_id: "iii::durable::publish".to_string(),
    payload: json!({"topic": "test"}),
    action: Some(TriggerAction::Enqueue { queue: "test".to_string() }),
    timeout_ms: None,
}).await?;

register_trigger_type

Register a custom trigger type with the engine. Returns a TriggerTypeRef handle that can register triggers and functions with compile-time validated types. Signature
register_trigger_type(trigger_type: RegisterTriggerType<H, C, R>) -> TriggerTypeRef<C, R>

Parameters

NameTypeRequiredDescription
trigger_typeRegisterTriggerType<H, C, R>Yes-

Example

let my_trigger = worker.register_trigger_type(
    RegisterTriggerType::new("my-trigger", "My custom trigger", MyHandler)
        .trigger_request_format::<MyConfig>()
        .call_request_format::<MyRequest>(),
);

// Compile-time safe: config must be MyConfig, function input must be MyRequest
my_trigger.register_function("my::handler", |req: MyRequest| -> Result<serde_json::Value, iii_sdk::Error> {
    Ok(serde_json::json!({ "data": req.data }))
});
my_trigger.register_trigger("my::handler", MyConfig { url: "/hook".into() });

unregister_trigger_type

Unregister a previously registered trigger type. Signature
unregister_trigger_type(id: impl Into<String>)

Parameters

NameTypeRequiredDescription
idimpl Into<String>Yes-

get_connection_state

Get the current connection state. Signature
get_connection_state() -> IIIConnectionState

shutdown

Shutdown the III client and wait for the connection thread to finish. This stops the connection loop, sends a shutdown signal, and joins the background connection thread. OpenTelemetry is flushed inside the connection thread before it exits. Signature
shutdown()

shutdown_async

Shutdown the III client. This stops the connection loop and sends a shutdown signal, but it does not join connection_thread. Unlike shutdown, this method does not block to wait for run_connection() to finish, making it safe to call from an async context without stalling the executor. The OpenTelemetry flush (telemetry::shutdown_otel()) still runs inside the connection thread after run_connection() returns, so it may not complete unless shutdown is used to join the thread. Signature
async shutdown_async()

Types

iii_sdk

EnqueueResult · InitOptions · RegisterFunction · RegisterTriggerType · TelemetryOptions

EnqueueResult

Result returned by the engine when a message is successfully enqueued.
NameTypeRequiredDescription
message_receipt_idStringYes-

InitOptions

Configuration options passed to register_worker.
NameTypeRequiredDescription
metadataOption<iii::WorkerMetadata>NoCustom worker metadata. Auto-detected if None.
headersOption<HashMap<String, String>>NoCustom HTTP headers sent during the WebSocket handshake.
otelOption<iii_helpers::observability::OtelConfig>NoOpenTelemetry configuration.

RegisterFunction

Function registration builder. The function ID is supplied separately at registration time via IIIClient::register_function, RegisterFunction only carries the handler and optional metadata. Constructors:
  • RegisterFunction::new: sync function. Accepts both typed handlers (schemas auto-extracted via schemars) and Fn(Value) -> Result<Value, Error> closures (permissive AnyValue schema, since Value: JsonSchema).
  • RegisterFunction::new_async: async equivalent of new.
  • RegisterFunction::new_async_with_bad_request: typed async handler that routes payload-deserialization failures through a caller-supplied mapper instead of the SDK’s generic Error::Serde.
  • RegisterFunction::http: function invoked over HTTP (Lambda, Cloudflare Workers, etc.).
Builder methods (all consume self):
  • description
  • metadata
  • request_format: overrides any auto-extracted schema.
  • response_format: overrides any auto-extracted schema.

RegisterTriggerType

Builder for registering a custom trigger type with optional format schemas. Type parameters:
  • C tracks the trigger registration type (set via .trigger_request_format::<T>())
  • R tracks the call request type (set via .call_request_format::<T>())
Both default to Value (untyped) and change when the respective builder method is called. This allows IIIClient::register_trigger_type to return a TriggerTypeRef<C, R> with compile-time safety for both config and function input types.

TelemetryOptions

Worker metadata provided by the SDK to the engine.
NameTypeRequiredDescription
languageOption<String>No-
project_nameOption<String>No-
frameworkOption<String>No-
amplitude_api_keyOption<String>No-

iii_sdk::builtin_triggers

CronCallRequest · CronTriggerConfig · HttpCallRequest · HttpMethod · HttpTriggerConfig · LogCallRequest · LogLevel · LogTriggerConfig · QueueTriggerConfig · StateCallRequest · StateEventType · StateTriggerConfig · SubscribeTriggerConfig

CronCallRequest

NameTypeRequiredDescription
triggerStringYes-
job_idStringYes-
scheduled_timeStringYes-
actual_timeStringYes-

CronTriggerConfig

NameTypeRequiredDescription
expressionStringYesCron expression (6-field format: sec min hour day month weekday)
condition_function_idOption<String>NoOptional function ID to evaluate before invoking handler

HttpCallRequest

NameTypeRequiredDescription
query_paramsHashMap<String, String>Yes-
path_paramsHashMap<String, String>Yes-
headersHashMap<String, String>Yes-
pathStringYes-
methodStringYes-
bodyValueYes-

HttpMethod

NameTypeRequiredDescription
GetunitYes-
PostunitYes-
PutunitYes-
DeleteunitYes-
PatchunitYes-
HeadunitYes-
OptionsunitYes-

HttpTriggerConfig

NameTypeRequiredDescription
api_pathStringYesHTTP endpoint path (e.g. /users/:id)
http_methodOption<HttpMethod>NoHTTP method (defaults to GET)
condition_function_idOption<String>NoOptional function ID to evaluate before invoking handler

LogCallRequest

NameTypeRequiredDescription
timestamp_unix_nanou64Yes-
observed_timestamp_unix_nanou64Yes-
severity_numberu32Yes-
severity_textStringYes-
bodyStringYes-
attributesValueYes-
trace_idStringYes-
span_idStringYes-
resourceValueYes-
service_nameStringYes-
instrumentation_scope_nameStringYes-
instrumentation_scope_versionStringYes-

LogLevel

NameTypeRequiredDescription
AllunitYes-
DebugunitYes-
InfounitYes-
WarnunitYes-
ErrorunitYes-

LogTriggerConfig

NameTypeRequiredDescription
levelOption<LogLevel>NoMinimum log level to trigger on

QueueTriggerConfig

NameTypeRequiredDescription
topicStringYesQueue topic to subscribe to
condition_function_idOption<String>NoOptional function ID to evaluate before invoking handler
queue_configOption<Value>NoQueue-specific subscriber configuration

StateCallRequest

NameTypeRequiredDescription
message_typeStringYes-
event_typeStateEventTypeYes-
scopeStringYes-
keyStringYes-
old_valueOption<Value>No-
new_valueValueYes-

StateEventType

NameTypeRequiredDescription
CreatedunitYes-
UpdatedunitYes-
DeletedunitYes-

StateTriggerConfig

NameTypeRequiredDescription
scopeOption<String>NoState scope to watch (exact match filter)
keyOption<String>NoState key to watch (exact match filter)
condition_function_idOption<String>NoOptional function ID to evaluate before invoking handler

SubscribeTriggerConfig

NameTypeRequiredDescription
topicStringYesTopic to subscribe to
condition_function_idOption<String>NoOptional function ID to evaluate before invoking handler

iii_sdk::channel

Channel · ChannelReader · ChannelWriter · StreamChannelRef

Channel

A streaming channel pair for worker-to-worker data transfer.
NameTypeRequiredDescription
writerChannelWriterYes-
readerChannelReaderYes-
writer_refStreamChannelRefYes-
reader_refStreamChannelRefYes-

ChannelReader

WebSocket-backed reader for streaming binary data and text messages.

ChannelWriter

WebSocket-backed writer for streaming binary data and text messages.

StreamChannelRef

NameTypeRequiredDescription
channel_idStringYes-
access_keyStringYes-
directionChannelDirectionYes-

iii_sdk::channels

ChannelDirection · ChannelItem

ChannelDirection

NameTypeRequiredDescription
ReadunitYes-
WriteunitYes-

ChannelItem

NameTypeRequiredDescription
Text(String)Yes-
Binary(Vec<u8>)Yes-

iii_sdk::engine

EngineFunctions · EngineTriggers

EngineFunctions

Engine function ids for internal operations.

EngineTriggers

Engine trigger ids.

iii_sdk::errors

Error · InvocationError

Error

Errors returned by the III SDK.
NameTypeRequiredDescription
NotConnectedunitYes-
TimeoutunitYes-
Runtime(String)Yes-
Remote{ code: String, message: String, stacktrace: Option<String> }Yes-
Handler(String)Yes-
Serde(String)Yes-
WebSocket(String)Yes-

InvocationError

Structured invocation failure, mirroring the Node and Python InvocationError. Produced from the Error::Remote variant via Error::invocation_error. function_id is None from that accessor because the wire Remote payload does not carry it.
NameTypeRequiredDescription
codeStringYes-
messageStringYes-
function_idOption<String>No-
stacktraceOption<String>No-

iii_sdk::protocol

ErrorBody · FunctionMessage · Message · RegisterFunctionMessage · RegisterTriggerInput · RegisterTriggerMessage · RegisterTriggerTypeMessage · TriggerAction · TriggerRequest · UnregisterTriggerMessage · UnregisterTriggerTypeMessage

ErrorBody

NameTypeRequiredDescription
codeStringYes-
messageStringYes-
stacktraceOption<String>No-

FunctionMessage

NameTypeRequiredDescription
function_idStringYes-
descriptionOption<String>No-
request_formatOption<Value>No-
response_formatOption<Value>No-
metadataOption<Value>No-

Message

NameTypeRequiredDescription
RegisterTriggerType{ id: String, description: String, trigger_request_format: Option<Value>, call_request_format: Option<Value> }Yes-
RegisterTrigger{ id: String, trigger_type: String, function_id: String, config: Value, metadata: Option<Value> }Yes-
TriggerRegistrationResult{ id: String, trigger_type: String, function_id: String, error: Option<ErrorBody> }Yes-
UnregisterTrigger{ id: String, trigger_type: String }Yes-
UnregisterTriggerType{ id: String }Yes-
RegisterFunction{ id: String, description: Option<String>, request_format: Option<Value>, response_format: Option<Value>, metadata: Option<Value>, invocation: Option<iii_helpers::http::HttpInvocationConfig> }Yes-
UnregisterFunction{ id: String }Yes-
InvokeFunction{ invocation_id: Option<uuid::Uuid>, function_id: String, data: Value, traceparent: Option<String>, baggage: Option<String>, action: Option<TriggerAction> }Yes-
InvocationResult{ invocation_id: uuid::Uuid, function_id: String, result: Option<Value>, error: Option<ErrorBody>, traceparent: Option<String>, baggage: Option<String> }Yes-
PingunitYes-
PongunitYes-
WorkerRegistered{ worker_id: String }Yes-

RegisterFunctionMessage

NameTypeRequiredDescription
idStringYes-
descriptionOption<String>No-
request_formatOption<Value>No-
response_formatOption<Value>No-
metadataOption<Value>No-
invocationOption<iii_helpers::http::HttpInvocationConfig>No-

RegisterTriggerInput

Input for IIIClient::register_trigger. The id is auto-generated internally.
NameTypeRequiredDescription
trigger_typeStringYes-
function_idStringYes-
configValueYes-
metadataOption<Value>No-

RegisterTriggerMessage

NameTypeRequiredDescription
idStringYes-
trigger_typeStringYes-
function_idStringYes-
configValueYes-
metadataOption<Value>No-

RegisterTriggerTypeMessage

NameTypeRequiredDescription
idStringYes-
descriptionStringYes-
trigger_request_formatOption<Value>No-
call_request_formatOption<Value>No-

TriggerAction

Routing action for TriggerRequest. Determines how the engine handles the invocation.
  • Enqueue — Routes through a named queue for async processing.
  • Void — Fire-and-forget, no response.
NameTypeRequiredDescription
Enqueue{ queue: String }YesRoutes the invocation through a named queue.
VoidunitYesFire-and-forget routing.

TriggerRequest

Request object for trigger(). Matches the Node/Python SDK signature: trigger({ function_id, payload, action?, timeout_ms? })
NameTypeRequiredDescription
function_idStringYes-
payloadValueYes-
actionOption<TriggerAction>No-
timeout_msOption<u64>No-

UnregisterTriggerMessage

NameTypeRequiredDescription
idStringYes-
trigger_typeStringYes-

UnregisterTriggerTypeMessage

NameTypeRequiredDescription
idStringYes-

iii_sdk::runtime

FunctionInfo · FunctionRef · IIIConnectionState · TriggerInfo · TriggerTypeRef · WorkerInfo · WorkerMetadata

FunctionInfo

Function information returned by engine::functions::list
NameTypeRequiredDescription
function_idStringYes-
descriptionOption<String>No-
request_formatOption<Value>No-
response_formatOption<Value>No-
metadataOption<Value>No-

FunctionRef

NameTypeRequiredDescription
idStringYes-

IIIConnectionState

Connection state for the III WebSocket client
NameTypeRequiredDescription
DisconnectedunitYes-
ConnectingunitYes-
ConnectedunitYes-
ReconnectingunitYes-
FailedunitYes-

TriggerInfo

Trigger information returned by engine::triggers::list
NameTypeRequiredDescription
idStringYes-
trigger_typeStringYes-
function_idStringYes-
configValueYes-
metadataOption<Value>No-

TriggerTypeRef

Typed handle returned by IIIClient::register_trigger_type. Type parameters:
  • C: trigger registration type for register_trigger
  • R: call request type for register_function

WorkerInfo

Worker information returned by engine::workers::list
NameTypeRequiredDescription
idStringYes-
nameOption<String>No-
runtimeOption<String>No-
versionOption<String>No-
osOption<String>No-
ip_addressOption<String>No-
statusStringYes-
connected_at_msu64Yes-
function_countusizeYes-
functionsVec<String>Yes-
active_invocationsusizeYes-
isolationOption<String>No-

WorkerMetadata

Worker metadata for auto-registration
NameTypeRequiredDescription
runtimeStringYes-
versionStringYes-
nameStringYes-
osStringYes-
descriptionOption<String>NoOne-line, human/LLM-readable summary of what this worker does.
Surfaces in engine::workers::list / engine::workers::info.
pidOption<u32>No-
telemetryOption<TelemetryOptions>No-
isolationOption<String>No-

iii_sdk::structs

MiddlewareFunctionInput

MiddlewareFunctionInput

Input passed to the RBAC middleware function on every function invocation through the RBAC port. The middleware can inspect, modify, or reject the call before it reaches the target function.
NameTypeRequiredDescription
function_idStringYesID of the function being invoked.
payloadValueYesPayload sent by the caller.
actionOption<TriggerAction>NoRouting action, if any.
contextValueYesAuth context returned by the auth function for this session.

iii_sdk::trigger

IIITrigger · Trigger · TriggerConfig

IIITrigger

Enum of all built-in trigger types with typed configuration. Use .for_function() to create a RegisterTriggerInput:
NameTypeRequiredDescription
Http(HttpTriggerConfig)Yes-
Cron(CronTriggerConfig)Yes-
Queue(QueueTriggerConfig)Yes-
Subscribe(SubscribeTriggerConfig)Yes-
State(StateTriggerConfig)Yes-
Stream(iii_helpers::stream::StreamTriggerConfig)Yes-
StreamJoin(iii_helpers::stream::StreamJoinLeaveTriggerConfig)Yes-
StreamLeave(iii_helpers::stream::StreamJoinLeaveTriggerConfig)Yes-
Log(LogTriggerConfig)Yes-

Trigger

Handle returned by IIIClient::register_trigger. Call unregister to remove the trigger from the engine.

TriggerConfig

Configuration passed to a TriggerHandler when a trigger instance is registered or unregistered.
NameTypeRequiredDescription
idStringYesTrigger instance ID.
function_idStringYesFunction to invoke when the trigger fires.
configValueYesTrigger-specific configuration.
metadataOption<Value>NoArbitrary metadata attached to the trigger.

iii_sdk::types

RemoteFunctionData · RemoteFunctionHandler · RemoteTriggerTypeData · StreamRequest · StreamResponse

RemoteFunctionData

NameTypeRequiredDescription
messageRegisterFunctionMessageYes-
handlerOption<RemoteFunctionHandler>No-

RemoteFunctionHandler

type RemoteFunctionHandler = std::sync::Arc<dyn Fn + Send + Sync>

RemoteTriggerTypeData

NameTypeRequiredDescription
messageRegisterTriggerTypeMessageYes-
handlerstd::sync::Arc<dyn TriggerHandler>Yes-

StreamRequest

Streaming request type, mirroring the Node and Python StreamRequest. Alias of iii_helpers::http::HttpRequest; added for cross-language parity.
type StreamRequest = iii_helpers::http::HttpRequest<T>

StreamResponse

Streaming response type, mirroring the Node and Python StreamResponse. Alias of iii_helpers::http::HttpResponse; added for cross-language parity.
type StreamResponse = iii_helpers::http::HttpResponse<T>