tendermint/docs/spec/abci/README.md

ABCI

ABCI is the interface between Tendermint (a state-machine replication engine) and an application (the actual state machine). It consists of a set of methods, where each method has a corresponding Request and Response message type. Tendermint calls the ABCI methods on the ABCI application by sending the Request* messages and receiving the Response* messages in return.

All message types are defined in a protobuf file. This allows Tendermint to run applications written in any programming language.

This specification is split as follows:

• Methods and Types - complete details on all ABCI methods and message types
• Applications - how to manage ABCI application state and other details about building ABCI applications
• Client and Server - for those looking to implement their own ABCI application servers