49 lines
1.7 KiB
Markdown
49 lines
1.7 KiB
Markdown
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# Application Blockchain Interface (ABCI)
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ABCI is the interface between Tendermint (a state-machine replication engine)
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and an application (the actual state machine).
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The ABCI message types are defined in a [protobuf
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file](https://github.com/tendermint/abci/blob/master/types/types.proto).
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For full details on the ABCI message types and protocol, see the [ABCI
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specificaiton](https://github.com/tendermint/abci/blob/master/specification.rst).
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For additional details on server implementation, see the [ABCI
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readme](https://github.com/tendermint/abci#implementation).
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Here we provide some more details around the use of ABCI by Tendermint and
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clarify common "gotchas".
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## Validator Updates
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Updates to the Tendermint validator set can be made by returning `Validator`
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objects in the `ResponseBeginBlock`:
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```
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message Validator {
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bytes pub_key = 1;
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int64 power = 2;
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}
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```
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The `pub_key` is the Amino encoded public key for the validator. For details on
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Amino encoded public keys, see the [section of the encoding spec](./encoding.md#public-key-cryptography).
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For example, the 32-byte Ed25519 pubkey
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`76852933A4686A721442E931A8415F62F5F1AEDF4910F1F252FB393F74C40C85` would be
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Amino encoded as
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`1624DE622076852933A4686A721442E931A8415F62F5F1AEDF4910F1F252FB393F74C40C85`
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The `power` is the new voting power for the validator, with the
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following rules:
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- power must be non-negative
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- if power is 0, the validator must already exist, and will be removed from the
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validator set
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- if power is non-0:
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- if the validator does not already exist, it will be added to the validator
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set with the given power
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- if the validator does already exist, its power will be adjusted to the given power
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## Query
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