BAC-L2-SUB-104Substrate / Polkadot SDK
Node architecture: client and runtime
The Polkadot SDK's founding split: a native client handling networking and the database, a WebAssembly runtime defining the rules — replaceable without redeploying the client.
- Level
- L2 — Appchain developer
- Duration
- 4 h
- Maintainer
- Polkadot / Substrate Lead Architect
Learning objectives
- 01Locate networking, database, consensus and runtime within the architecture
- 02Explain why the runtime is compiled to WebAssembly
- 03Identify what requires a client update and what does not
Guided lab
Walk a template node's source and map its layers onto a blank diagram.
Independent lab
Document an extrinsic's full execution path, from network arrival to its effect on state.
Security angle
The trust boundary between client and runtime: what each can do to the other.
Assessment
Architecture map, marked on the accuracy of the boundaries drawn.