BAC-L2-SUB-112Substrate / Polkadot SDK
Runtime APIs and custom RPC
Exposing a read the raw storage does not give directly, without turning the node into an application server.
- Level
- L2 — Appchain developer
- Duration
- 4 h
- Maintainer
- Polkadot / Substrate Lead Architect
Learning objectives
- 01Define a runtime API and expose it over RPC
- 02Separate what must be computed on-chain from what must not
- 03Version an API without breaking existing clients
Guided lab
Expose an aggregated view of the registry over RPC and query it from a TypeScript client.
Independent lab
Version the API and demonstrate two client generations coexisting.
Security angle
An unbounded public RPC is a denial-of-service vector: bound it, paginate it, rate-limit it.
Assessment
API successfully queried by a peer's client.