Consensus and validator queries

Use consensus query services to inspect validator information on proof of authority (PoA) networks.

PoaQueryService exposes:

• Validators for the latest block.
• The proposer of a block.
• The local signer address.

BftQueryService extends PoaQueryService for BFT-style PoA networks and exposes:

• The round number from a block header.
• Signers from a block header.
• The consensus mechanism name.

Handle these services as optional. They might not be available for every network configuration.

For example, expose the latest PoA validator count as a metric or RPC result:

@Override
public void start() {
  serviceManager
      .getService(PoaQueryService.class)
      .ifPresent(
          poa -> {
            int validatorCount = poa.getValidatorsForLatestBlock().size();
            Address localSigner = poa.getLocalSignerAddress();
          });
}

For BFT-specific metadata, combine BftQueryService with a block header:

@Override
public void start() {
  serviceManager
      .getService(BftQueryService.class)
      .ifPresent(
          bft -> {
            String consensusName = bft.getConsensusMechanismName();
            int round = bft.getRoundNumberFrom(blockHeader);
            Collection<Address> signers = bft.getSignersFrom(blockHeader);
          });
}