Resonate Recursive Fan-Out Pattern — Rust

SDK note. The Rust SDK is in active development (v0.6.0, on crates.io). This pattern uses ctx.run().spawn() and ctx.rpc().spawn() — both synchronous as of 0.5.0+. Verify against current SDK source before shipping.

Overview

Recursive fan-out spawns multiple child invocations in parallel, awaits them individually, and (optionally) recurses deeper. The Rust expression uses .spawn() on a Context execution builder to get a DurableFuture, collects those futures into a Vec, then awaits each in turn.

For the language-agnostic mental model, see resonate-recursive-fan-out-pattern-typescript.

When to use

• Batch processing where items are independent
• Web crawling / tree traversal with dynamic depth
• Map-reduce shaped workflows
• Any fan-out where each leaf is a discrete, retryable unit

Parallel fan-out in the same process