BAC-L2-COSMOS-104Cosmos SDK
CometBFT and the ABCI interface
The most important boundary in the Cosmos stack: consensus orders transactions, the application decides their effect. The two know each other only through an interface.
- Level
- L2 — Appchain developer
- Duration
- 4 h
- Track
- Cosmos SDK
- Maintainer
- Cosmos Lead Architect
Learning objectives
- 01Describe a block's cycle through the ABCI calls
- 02Explain the deterministic finality the consensus provides
- 03Identify what must remain deterministic on the application side
Guided lab
Write a minimal ABCI application and drive it with a local consensus engine.
Independent lab
Introduce non-determinism into the application and observe the divergence between nodes.
Security angle
A non-deterministic application breaks consensus: reproduce the halt, then fix it.
Assessment
Working ABCI application plus a write-up of the non-determinism experiment.