InvokeFunction

Invoke a registered function

Request

Invoke a function that has been registered with the framework.

Response

The framework responds with an InvocationResult message.

type · string

Message type. Will be "invocationresult".

invocation_id · string · required

UUID that identifies this invocation. Matches the request’s invocation_id if provided.

function_id · string · required

The ID of the function that was invoked.

result · any

The successful result from the function. Omitted if the invocation failed.

error · object

Error details if the invocation failed. Omitted if successful.

Show properties

code · string · required

Machine-readable error code (e.g., "function_not_found", "timeout", "execution_error").

message · string · required

Human-readable error message describing what went wrong.

traceparent · string

W3C trace-context traceparent header, propagated from the request or generated.

baggage · string

W3C baggage header, propagated from the request.

Examples

Basic Function Invocation

Request:

{
  "type": "invokefunction",
  "function_id": "process_payment",
  "data": {
    "amount": 99.99,
    "currency": "USD"
  }
}

Success Response:

{
  "type": "invocationresult",
  "invocation_id": "550e8400-e29b-41d4-a716-446655440000",
  "function_id": "process_payment",
  "result": {
    "transaction_id": "txn_abc123",
    "status": "completed"
  }
}

Invocation with Custom ID

Request:

{
  "type": "invokefunction",
  "invocation_id": "550e8400-e29b-41d4-a716-446655440000",
  "function_id": "send_email",
  "data": {
    "to": "[e-mail]",
    "subject": "Welcome!",
    "body": "Thanks for signing up."
  }
}

Success Response:

{
  "type": "invocationresult",
  "invocation_id": "550e8400-e29b-41d4-a716-446655440000",
  "function_id": "send_email",
  "result": {
    "message_id": "msg_xyz789",
    "status": "sent"
  }
}

Invocation with Distributed Tracing

Request:

{
  "type": "invokefunction",
  "function_id": "process_order",
  "data": {
    "order_id": "ord_123",
    "items": [{ "sku": "ITEM-001", "quantity": 2 }]
  },
  "traceparent": "00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01",
  "baggage": "user_id=12345,session_id=abc"
}

Success Response:

{
  "type": "invocationresult",
  "invocation_id": "7c9e6679-7425-40de-944b-e07fc1f90ae7",
  "function_id": "process_order",
  "result": {
    "order_status": "confirmed",
    "estimated_delivery": "2026-03-05"
  },
  "traceparent": "00-4bf92f3577b34da6a3ce929d0e0e4736-b7ad6b7169203331-01",
  "baggage": "user_id=12345,session_id=abc"
}

Error Cases

Function Not Found

Request:

{
  "type": "invokefunction",
  "function_id": "nonexistent_function",
  "data": {}
}

Error Response:

{
  "type": "invocationresult",
  "invocation_id": "550e8400-e29b-41d4-a716-446655440000",
  "function_id": "nonexistent_function",
  "error": {
    "code": "function_not_found",
    "message": "No function registered with ID 'nonexistent_function'"
  }
}

Execution Error

Request:

{
  "type": "invokefunction",
  "function_id": "divide_numbers",
  "data": {
    "numerator": 10,
    "denominator": 0
  }
}

Error Response:

{
  "type": "invocationresult",
  "invocation_id": "550e8400-e29b-41d4-a716-446655440000",
  "function_id": "divide_numbers",
  "error": {
    "code": "execution_error",
    "message": "Division by zero"
  }
}

Timeout Error

Error Response:

{
  "type": "invocationresult",
  "invocation_id": "550e8400-e29b-41d4-a716-446655440000",
  "function_id": "slow_operation",
  "error": {
    "code": "timeout",
    "message": "Function execution exceeded timeout of 30000ms"
  }
}

Notes

• The invocation_id is used to correlate requests with responses
• If no invocation_id is provided, one will be generated automatically
• The result and error fields are mutually exclusive - only one will be present
• For HTTP-based functions, the HTTP response body is returned as the result
• For WebSocket-based functions, the worker must send an InvocationResult message
• Distributed tracing headers follow the W3C Trace Context specification