This document explains the methods in the NEO SDK that are related to voting.
Namespace: Neo.SmartContract.Framework.Services.Neo
Assembly: Neo.SmartContract.Framework
| Name | Description | |
|---|---|---|
 |
Wallet.Vote(NeoSystem, UInt160, byte[]) | Votes for candidates |
|
Snapshot.GetRegisteredVotes() | Returns a dictionary with candidates and the number of votes they each have |
|
Snapshot.GetSupporters() | Returns a dictionary with candidates and a list of addresses that voted for each one |
|
Snapshot.GetSupporters(ECPoint) | Returns a list of addresses that voted for the specified public key |
Read How Voting Works in NEO first to learn how voting works at a high level. What follows is a more technical explanation oriented toward developers.
Because transactions are what are recorded on the NEO ledger, voting is implemented as a transaction. In particular,
when Vote(system, scriptHash, candidates) is called, a StateTransaction is created
with a StateDescriptor containing a Type, Key, Field, and Value.
- The
TypeisStateType.Account, representing that theKeyis that of a voter, not a candidate. - The
Keyis the byte array ofscriptHash, which represents the voting account (it is the script hash of the address of the voting account). - The
Fieldis set to "Votes" - The
Valueis set tocandidates(the public keys of the nodes being voted for).
After the transaction is made, it must be signed. Every transaction requires one or more signatures to prove consent by those involved, and voting is no different. Thus, this transaction is placed in a
ContractParametersContext, which contains the field Signatures. In general, once all parties to a
transactions sign it (i.e., their signatures get added to Signatures), then the field Completed becomes true. Once that happens, the transaction is broadcast to be confirmed by the blockchain.
In Vote(system, scriptHash, candidates), the transaction is signed by the account referenced by scriptHash and then broadcast to the NEO blockchain. (That blockchain is referenced in system, a NeoSystem).
Each account can vote for multiple candidates; i.e., the candidates parameter may contain multiple public keys. Each of those candidates receives votes equal to the amount of NEO owned by that account.
Votes are transferred when NEO is transferred. That is, when x amount of NEO is transferred from account A to account B, the candidates voted for by account A will lose x votes and the candidates voted for by account B will gain x votes. This is updated in real time. The paragraph below explains how this works.
The top N candidates become consensus nodes, where N is determined by the algorithm described here.
The way this works is when GetValidators(transactions) is called, GetValidators first takes a Snapshot of the blockchain
and updates the NEO for each account based on transactions while simultaneously modifying the votes of each candidate voted for by those accounts according to the NEO transfers in transactions.
Then the registered candidates with a positive number of votes are combined with the active standby validators, and this list is sorted to find the N nodes with the most votes, which are returned as the new validators (consensus nodes).
If this list has length less than N, inactive standby validators become active and are added to the validator list until its length reaches N. Thus, there will be N new consensus nodes.