Module invoke 

Workers invoked over HTTP: suspend to zero.

A server configured with Endpoints (Server::set_invokers) sends an HTTP POST to one when a shard that no worker holds has work due (a client call, a message from another shard, a timer, or a holder that left without saying what was next). The process that receives it (a function on Lambda, Cloud Run or Vercel, or any HTTP server) hands the request to a Handler, which connects to the server as a worker for exactly that invocation’s shards, runs them until they are idle or the invocation’s budget ends, reports each shard’s next due time and returns. The server invokes again when more work comes; nothing stays up while workflows sleep. Leases, epochs and fencing are those of every worker, so exactly-once effects are unchanged. See docs/server-mode.md.

Structs

Endpoint

An HTTP endpoint the server invokes workers at.

EndpointMetrics

One endpoint’s counters.

Handler

The worker side of an invocation, for any HTTP framework: give it the request’s fusee-signature header and body, answer with its Reply. Each call opens a fresh engine and closes it before it returns; nothing is kept between invocations.

InvokeMetrics

The invoker’s counters (Server::invocation_metrics).

Reply

What a Handler answers: an HTTP status and a JSON body.

Request

The body of an invocation request.

Secret

A secret whose bytes are never printed.

Enums

Progress

Where an invoked worker’s invocation stands (Remote::invocation_poll).

Constants

PARK_AFTER

How long a suspended run stays loaded in an invoked worker before it is parked (written to the run store). Short: the worker leaves soon, and a parked run costs the next invocation’s open almost nothing.

SIGNATURE_HEADER

The header that carries the request’s signature.

SIGNATURE_TOLERANCE

How old a signature a handler accepts.

Functions

format_id

An invocation ID as the request and the invocation= option carry it: 16 lowercase hex digits.

parse_id

Parses format_id’s output.

serve

Serves handler over HTTP on listener until the task is cancelled: a self-hosted endpoint. With tls, over HTTPS; a CA in tls requires the server’s client certificate (mutual TLS).

serve_with

Like serve, answering each POST with answer(signature header, body): for a process that hands invocations on (to a child process, a queue) instead of running them itself.

sign

The fusee-signature value for body signed at t_ms (Unix ms): t=<t_ms>,v1=<hex HMAC-SHA256(secret, "<t_ms>." + body)>.

verify

Checks a fusee-signature value against body at now_ms: the MAC (in constant time) and the timestamp, within SIGNATURE_TOLERANCE.

with_invocation

address with invocation=<id> among its options.