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@ -5,30 +5,31 @@ the next block to be added to the Tendermint blockchain. The protocol proceeds i |
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each round is a try to reach agreement on the next block. A round starts by having a dedicated |
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process (called proposer) suggesting to other processes what should be the next block with |
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the `ProposalMessage`. |
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The processes respond by voting for a block with `VoteMessage` (there are two kinds of vote messages, prevote |
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and precommit votes). Note that a proposal message is just a suggestion what the next block should be; a |
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validator might vote with a `VoteMessage` for a different block. If in some round, enough number |
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of processes vote for the same block, then this block is committed and later added to the blockchain. |
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`ProposalMessage` and `VoteMessage` are signed by the private key of the validator. |
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The internals of the protocol and how it ensures safety and liveness properties are |
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The processes respond by voting for a block with `VoteMessage` (there are two kinds of vote |
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messages, prevote and precommit votes). Note that a proposal message is just a suggestion what the |
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next block should be; a validator might vote with a `VoteMessage` for a different block. If in some |
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round, enough number of processes vote for the same block, then this block is committed and later |
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added to the blockchain. `ProposalMessage` and `VoteMessage` are signed by the private key of the |
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validator. The internals of the protocol and how it ensures safety and liveness properties are |
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explained [here](https://github.com/tendermint/spec). |
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For efficiency reasons, validators in Tendermint consensus protocol do not agree directly on the block |
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as the block size is big, i.e., they don't embed the block inside `Proposal` and `VoteMessage`. Instead, they |
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reach agreement on the `BlockID` (see `BlockID` definition in [Blockchain](blockchain.md) section) |
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that uniquely identifies each block. The block itself is disseminated to validator processes using |
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peer-to-peer gossiping protocol. It starts by having a proposer first splitting a block into a |
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number of block parts, that are then gossiped between processes using `BlockPartMessage`. |
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For efficiency reasons, validators in Tendermint consensus protocol do not agree directly on the |
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block as the block size is big, i.e., they don't embed the block inside `Proposal` and |
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`VoteMessage`. Instead, they reach agreement on the `BlockID` (see `BlockID` definition in |
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[Blockchain](blockchain.md) section) that uniquely identifies each block. The block itself is |
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disseminated to validator processes using peer-to-peer gossiping protocol. It starts by having a |
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proposer first splitting a block into a number of block parts, that are then gossiped between |
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processes using `BlockPartMessage`. |
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Validators in Tendermint communicate by peer-to-peer gossiping protocol. Each validator is connected |
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only to a subset of processes called peers. By the gossiping protocol, a validator send to its peers |
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all needed information (`ProposalMessage`, `VoteMessage` and `BlockPartMessage`) so they can |
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reach agreement on some block, and also obtain the content of the chosen block (block parts). As part of |
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the gossiping protocol, processes also send auxiliary messages that inform peers about the |
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reach agreement on some block, and also obtain the content of the chosen block (block parts). As |
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part of the gossiping protocol, processes also send auxiliary messages that inform peers about the |
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executed steps of the core consensus algorithm (`NewRoundStepMessage` and `CommitStepMessage`), and |
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also messages that inform peers what votes the process has seen (`HasVoteMessage`, |
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`VoteSetMaj23Message` and `VoteSetBitsMessage`). These messages are then used in the gossiping protocol |
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to determine what messages a process should send to its peers. |
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`VoteSetMaj23Message` and `VoteSetBitsMessage`). These messages are then used in the gossiping |
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protocol to determine what messages a process should send to its peers. |
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We now describe the content of each message exchanged during Tendermint consensus protocol. |
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@ -45,9 +46,9 @@ type ProposalMessage struct { |
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### Proposal |
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Proposal contains height and round for which this proposal is made, BlockID as a unique identifier of proposed |
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block, timestamp, and two fields (POLRound and POLBlockID) that are needed for termination of the consensus. |
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The message is signed by the validator private key. |
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Proposal contains height and round for which this proposal is made, BlockID as a unique identifier |
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of proposed block, timestamp, and two fields (POLRound and POLBlockID) that are needed for |
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termination of the consensus. The message is signed by the validator private key. |
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```go |
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type Proposal struct { |
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@ -67,10 +68,11 @@ BlockID contains PartSetHeader. |
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## VoteMessage |
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VoteMessage is sent to vote for some block (or to inform others that a process does not vote in the current round). |
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Vote is defined in [Blockchain](blockchain.md) section and contains validator's information (validator address |
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and index), height and round for which the vote is sent, vote type, blockID if process vote for some |
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block (`nil` otherwise) and a timestamp when the vote is sent. The message is signed by the validator private key. |
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VoteMessage is sent to vote for some block (or to inform others that a process does not vote in the |
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current round). Vote is defined in [Blockchain](blockchain.md) section and contains validator's |
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information (validator address and index), height and round for which the vote is sent, vote type, |
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blockID if process vote for some block (`nil` otherwise) and a timestamp when the vote is sent. The |
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message is signed by the validator private key. |
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```go |
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type VoteMessage struct { |
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@ -120,9 +122,9 @@ type Heartbeat struct { |
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## NewRoundStepMessage |
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NewRoundStepMessage is sent for every step transition during the core consensus algorithm execution. It is |
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used in the gossip part of the Tendermint protocol to inform peers about a current height/round/step |
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a process is in. |
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NewRoundStepMessage is sent for every step transition during the core consensus algorithm execution. |
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It is used in the gossip part of the Tendermint protocol to inform peers about a current |
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height/round/step a process is in. |
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```go |
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type NewRoundStepMessage struct { |
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@ -136,10 +138,10 @@ type NewRoundStepMessage struct { |
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## CommitStepMessage |
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CommitStepMessage is sent when an agreement on some block is reached. It contains height for which agreement |
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is reached, block parts header that describes the decided block and is used to obtain all block parts, |
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and a bit array of the block parts a process currently has, so its peers can know what parts |
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it is missing so they can send them. |
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CommitStepMessage is sent when an agreement on some block is reached. It contains height for which |
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agreement is reached, block parts header that describes the decided block and is used to obtain all |
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block parts, and a bit array of the block parts a process currently has, so its peers can know what |
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parts it is missing so they can send them. |
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```go |
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type CommitStepMessage struct { |
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