More repository work

Moved more repository-like methods from qora.* classes to repository.

Removed qora.block.BlockTransaction as it's pretty much internal to the HSQLDB repository.

Fixing qora.account.*

Fixing genesis-related classes: block, account, transaction...

src/data/transaction/GenesisTransactionData.java

@@ -14,7 +14,8 @@ public class GenesisTransactionData extends TransactionData {
 	// Constructors
 
 	public GenesisTransactionData(String recipient, BigDecimal amount, long timestamp, byte[] signature) {
-		super(TransactionType.GENESIS, BigDecimal.ZERO, new GenesisAccount().getPublicKey(), timestamp, signature);
+		// Zero fee
+		super(TransactionType.GENESIS, BigDecimal.ZERO, GenesisAccount.PUBLIC_KEY, timestamp, signature);
 
 		this.recipient = recipient;
 		this.amount = amount;

src/qora/account/Account.java

@@ -19,9 +19,7 @@ public class Account {
 
 	public Account(Repository repository, String address) throws DataException {
 		this.repository = repository;
-		this.accountData = this.repository.getAccountRepository().getAccount(address);
+		this.accountData = new AccountData(address);
-		if (this.accountData == null)
-			this.accountData = new AccountData(address);
 	}
 
 	public String getAddress() {

src/qora/account/GenesisAccount.java

@@ -1,9 +1,14 @@
 package qora.account;
 
+import repository.DataException;
+import repository.Repository;
+
 public final class GenesisAccount extends PublicKeyAccount {
 
-	public GenesisAccount() {
+	public static final byte[] PUBLIC_KEY = new byte[] { 1, 1, 1, 1, 1, 1, 1, 1 };
-		super(new byte[] { 1, 1, 1, 1, 1, 1, 1, 1 });
+
+	public GenesisAccount(Repository repository) throws DataException {
+		super(repository, PUBLIC_KEY);
 	}
 
 }

src/qora/account/PrivateKeyAccount.java

@@ -1,7 +1,9 @@
 package qora.account;
 
+import data.account.AccountData;
 import qora.crypto.Crypto;
 import qora.crypto.Ed25519;
+import repository.Repository;
 import utils.Pair;
 
 public class PrivateKeyAccount extends PublicKeyAccount {
@@ -15,11 +17,12 @@ public class PrivateKeyAccount extends PublicKeyAccount {
 	 * @param seed
 	 *            byte[32] used to create private/public key pair
 	 */
-	public PrivateKeyAccount(byte[] seed) {
+	public PrivateKeyAccount(Repository repository, byte[] seed) {
+		this.repository = repository;
 		this.seed = seed;
 		this.keyPair = Ed25519.createKeyPair(seed);
 		this.publicKey = keyPair.getB();
-		this.address = Crypto.toAddress(this.publicKey);
+		this.accountData = new AccountData(Crypto.toAddress(this.publicKey));
 	}
 
 	public byte[] getSeed() {

src/qora/account/PublicKeyAccount.java

@@ -2,13 +2,15 @@ package qora.account;
 
 import qora.crypto.Crypto;
 import qora.crypto.Ed25519;
+import repository.DataException;
+import repository.Repository;
 
 public class PublicKeyAccount extends Account {
 
 	protected byte[] publicKey;
 
-	public PublicKeyAccount(byte[] publicKey) {
+	public PublicKeyAccount(Repository repository, byte[] publicKey) throws DataException {
-		super(Crypto.toAddress(publicKey));
+		super(repository, Crypto.toAddress(publicKey));
 
 		this.publicKey = publicKey;
 	}
@@ -28,4 +30,8 @@ public class PublicKeyAccount extends Account {
 		}
 	}
 
+	public static String getAddress(byte[] publicKey) {
+		return Crypto.toAddress(publicKey);
+	}
+
 }

src/qora/block/Block.java

@@ -49,10 +49,10 @@ import utils.NTP;
 public class Block {
 
 	// Properties
-	private Repository repository;
+	protected Repository repository;
-	private BlockData blockData;
+	protected BlockData blockData;
-	private PublicKeyAccount generator;
+	protected PublicKeyAccount generator;
-	
+
 	// Other properties
 	protected List<Transaction> transactions;
 	protected BigDecimal cachedNextGeneratingBalance;
@@ -76,10 +76,10 @@ public class Block {
 
 	// Constructors
 
-	public Block(Repository repository, BlockData blockData) {
+	public Block(Repository repository, BlockData blockData) throws DataException {
 		this.repository = repository;
 		this.blockData = blockData;
-		this.generator = new PublicKeyAccount(blockData.getGeneratorPublicKey());
+		this.generator = new PublicKeyAccount(repository, blockData.getGeneratorPublicKey());
 	}
 
 	// Getters/setters
@@ -88,6 +88,10 @@ public class Block {
 		return this.blockData;
 	}
 
+	public PublicKeyAccount getGenerator() {
+		return this.generator;
+	}
+
 	// More information
 
 	/**
@@ -142,7 +146,7 @@ public class Block {
 		// XXX: why can't we simply load using block height?
 		BlockRepository blockRepo = this.repository.getBlockRepository();
 		BlockData firstBlock = this.blockData;
-		
+
 		try {
 			for (int i = 1; firstBlock != null && i < BLOCK_RETARGET_INTERVAL; ++i)
 				firstBlock = blockRepo.fromSignature(firstBlock.getReference());
@@ -200,10 +204,10 @@ public class Block {
 			throw new IllegalStateException("Block's transactions from repository do not match block's transaction count");
 
 		this.transactions = new ArrayList<Transaction>();
-		
+
 		for (TransactionData transactionData : transactionsData)
 			this.transactions.add(Transaction.fromData(transactionData));
-		
+
 		return this.transactions;
 	}
 
@@ -294,7 +298,6 @@ public class Block {
 		}
 	}
 
-
 	public boolean isSignatureValid() {
 		try {
 			// Check generator's signature first
@@ -320,7 +323,7 @@ public class Block {
 	 * 
 	 * @return true if block is valid, false otherwise.
 	 * @throws SQLException
-	 * @throws DataException 
+	 * @throws DataException
 	 */
 	public boolean isValid() throws SQLException, DataException {
 		// TODO
@@ -334,7 +337,7 @@ public class Block {
 			return false;
 
 		Block parentBlock = new Block(this.repository, parentBlockData);
-		
+
 		// Check timestamp is valid, i.e. later than parent timestamp and not in the future, within ~500ms margin
 		if (this.blockData.getTimestamp() < parentBlockData.getTimestamp() || this.blockData.getTimestamp() - BLOCK_TIMESTAMP_MARGIN > NTP.getTime())
 			return false;
@@ -410,7 +413,7 @@ public class Block {
 		return true;
 	}
 
-	public void process() throws DataException, SQLException {
+	public void process() throws DataException {
 		// Process transactions (we'll link them to this block after saving the block itself)
 		List<Transaction> transactions = this.getTransactions();
 		for (Transaction transaction : transactions)
@@ -422,7 +425,7 @@ public class Block {
 			this.generator.setConfirmedBalance(Asset.QORA, this.generator.getConfirmedBalance(Asset.QORA).add(blockFee));
 
 		// Link block into blockchain by fetching signature of highest block and setting that as our reference
-		int blockchainHeight = BlockChain.getHeight();
+		int blockchainHeight = this.repository.getBlockRepository().getBlockchainHeight();
 		BlockData latestBlockData = this.repository.getBlockRepository().fromHeight(blockchainHeight);
 		if (latestBlockData != null)
 			this.blockData.setReference(latestBlockData.getSignature());
@@ -435,7 +438,8 @@ public class Block {
 			Transaction transaction = transactions.get(sequence);
 
 			// Link transaction to this block
-			BlockTransactionData blockTransactionData = new BlockTransactionData(this.getSignature(), sequence, transaction.getTransactionData().getSignature());
+			BlockTransactionData blockTransactionData = new BlockTransactionData(this.getSignature(), sequence,
+					transaction.getTransactionData().getSignature());
 			this.repository.getBlockRepository().save(blockTransactionData);
 		}
 	}

src/qora/block/BlockChain.java

@@ -1,11 +1,14 @@
 package qora.block;
 
 import java.math.BigDecimal;
-import java.sql.ResultSet;
 import java.sql.SQLException;
 
-import database.DB;
+import data.block.BlockData;
 import qora.assets.Asset;
+import repository.BlockRepository;
+import repository.DataException;
+import repository.Repository;
+import repository.RepositoryManager;
 
 /**
  * Class representing the blockchain as a whole.
@@ -35,69 +38,43 @@ public class BlockChain {
 	 * 
 	 * @throws SQLException
 	 */
-	public static void validate() throws SQLException {
+	public static void validate() throws DataException {
 		// Check first block is Genesis Block
 		if (!isGenesisBlockValid())
 			rebuildBlockchain();
 	}
 
-	private static boolean isGenesisBlockValid() throws SQLException {
+	private static boolean isGenesisBlockValid() throws DataException {
-		int blockchainHeight = getHeight();
+		BlockRepository blockRepository = RepositoryManager.getRepository().getBlockRepository();
+
+		int blockchainHeight = blockRepository.getBlockchainHeight();
 		if (blockchainHeight < 1)
 			return false;
 
-		Block block = Block.fromHeight(1);
+		BlockData blockData = blockRepository.fromHeight(1);
-		if (block == null)
+		if (blockData == null)
 			return false;
 
-		return GenesisBlock.isGenesisBlock(block);
+		return GenesisBlock.isGenesisBlock(blockData);
 	}
 
-	private static void rebuildBlockchain() throws SQLException {
+	private static void rebuildBlockchain() throws DataException {
-		// (Re)build database
+		// (Re)build repository
-		DB.rebuild();
+		Repository repository = RepositoryManager.getRepository();
+		repository.rebuild();
 
 		// Add Genesis Block
-		GenesisBlock genesisBlock = GenesisBlock.getInstance();
+		GenesisBlock genesisBlock = new GenesisBlock(repository);
 		genesisBlock.process();
 
 		// Add QORA asset.
 		// NOTE: Asset's transaction reference is Genesis Block's generator signature which doesn't exist as a transaction!
+		// TODO construct Asset(repository, AssetData) then .save()?
 		Asset qoraAsset = new Asset(Asset.QORA, genesisBlock.getGenerator().getAddress(), "Qora", "This is the simulated Qora asset.", 10_000_000_000L, true,
-				genesisBlock.getGeneratorSignature());
+				genesisBlock.getBlockData().getGeneratorSignature());
 		qoraAsset.save();
-	}
 
-	/**
+		repository.saveChanges();
-	 * Return block height from DB using signature.
-	 * 
-	 * @param signature
-	 * @return height, or 0 if block not found.
-	 * @throws SQLException
-	 */
-	public static int getBlockHeightFromSignature(byte[] signature) throws SQLException {
-		ResultSet rs = DB.checkedExecute("SELECT height FROM Blocks WHERE signature = ?", signature);
-		if (rs == null)
-			return 0;
-
-		return rs.getInt(1);
-	}
-
-	/**
-	 * Return highest block height from DB.
-	 * 
-	 * @return height, or 0 if there are no blocks in DB (not very likely).
-	 */
-	public static int getHeight() {
-		try {
-			ResultSet rs = DB.checkedExecute("SELECT MAX(height) FROM Blocks");
-			if (rs == null)
-				return 0;
-
-			return rs.getInt(1);
-		} catch (SQLException e) {
-			return 0;
-		}
 	}
 
 	/**

src/qora/block/BlockTransaction.java

@@ -1,5 +0,0 @@
-package qora.block;
-
-public class BlockTransaction {
-
-}

src/qora/block/GenesisBlock.java

@@ -3,37 +3,34 @@ package qora.block;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.math.BigDecimal;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-import java.util.ArrayList;
 import java.util.Arrays;
 
 import com.google.common.primitives.Bytes;
 import com.google.common.primitives.Longs;
 
+import data.block.BlockData;
+import data.transaction.GenesisTransactionData;
+import data.transaction.TransactionData;
 import qora.account.GenesisAccount;
 import qora.crypto.Crypto;
-import qora.transaction.GenesisTransaction;
+import qora.transaction.Transaction;
-import qora.transaction.TransactionHandler;
+import repository.DataException;
+import repository.Repository;
 
 public class GenesisBlock extends Block {
 
-	private static GenesisBlock instance;
-
 	private static final int GENESIS_BLOCK_VERSION = 1;
 	private static final byte[] GENESIS_REFERENCE = new byte[] { 1, 1, 1, 1, 1, 1, 1, 1 }; // NOTE: Neither 64 nor 128 bytes!
 	private static final BigDecimal GENESIS_GENERATING_BALANCE = BigDecimal.valueOf(10_000_000L).setScale(8);
-	private static final GenesisAccount GENESIS_GENERATOR = new GenesisAccount();
+	private static final byte[] GENESIS_GENERATOR_PUBLIC_KEY = GenesisAccount.PUBLIC_KEY; // NOTE: 8 bytes not 32 bytes!
 	private static final long GENESIS_TIMESTAMP = 1400247274336L; // QORA RELEASE: Fri May 16 13:34:34.336 2014 UTC
 	private static final byte[] GENESIS_GENERATOR_SIGNATURE = calcSignature();
 	private static final byte[] GENESIS_TRANSACTIONS_SIGNATURE = calcSignature();
 
 	// Constructors
-	protected GenesisBlock() {
+	public GenesisBlock(Repository repository) throws DataException {
-		super(GENESIS_BLOCK_VERSION, GENESIS_REFERENCE, GENESIS_TIMESTAMP, GENESIS_GENERATING_BALANCE, GENESIS_GENERATOR, GENESIS_GENERATOR_SIGNATURE,
+		super(repository, new BlockData(GENESIS_BLOCK_VERSION, GENESIS_REFERENCE, 0, BigDecimal.ZERO.setScale(8), GENESIS_TRANSACTIONS_SIGNATURE, 1,
-				GENESIS_TRANSACTIONS_SIGNATURE, null, null, new ArrayList<TransactionHandler>());
+				GENESIS_TIMESTAMP, GENESIS_GENERATING_BALANCE, GENESIS_GENERATOR_PUBLIC_KEY, GENESIS_GENERATOR_SIGNATURE, null, null));
-
-		this.height = 1;
 
 		// Genesis transactions
 		addGenesisTransaction("QUD9y7NZqTtNwvSAUfewd7zKUGoVivVnTW", "7032468.191");
@@ -172,74 +169,35 @@ public class GenesisBlock extends Block {
 		addGenesisTransaction("QT79PhvBwE6vFzfZ4oh5wdKVsEazZuVJFy", "6360421.343");
 	}
 
-	/**
-	 * Return cached GenesisBlock to save constructing one from scratch.
-	 * 
-	 * @return GenesisBlock
-	 */
-	public static GenesisBlock getInstance() {
-		if (instance == null)
-			instance = new GenesisBlock();
-
-		return instance;
-	}
-
-	// Getters/setters
-
 	// More information
 
-	public static boolean isGenesisBlock(Block block) {
+	public static boolean isGenesisBlock(BlockData blockData) {
-		if (block.height != 1)
+		if (blockData.getHeight() != 1)
 			return false;
 
 		// Validate block signature
-		if (!Arrays.equals(GENESIS_GENERATOR_SIGNATURE, block.generatorSignature))
+		if (!Arrays.equals(GENESIS_GENERATOR_SIGNATURE, blockData.getGeneratorSignature()))
 			return false;
 
 		// Validate transactions signature
-		if (!Arrays.equals(GENESIS_TRANSACTIONS_SIGNATURE, block.transactionsSignature))
+		if (!Arrays.equals(GENESIS_TRANSACTIONS_SIGNATURE, blockData.getTransactionsSignature()))
 			return false;
 
 		return true;
 	}
 
-	// Load/Save
-
-	protected GenesisBlock(byte[] signature) throws SQLException {
-		super(signature);
-	}
-
-	protected GenesisBlock(ResultSet rs) throws SQLException {
-		super(rs);
-	}
-
-	// Navigation
-
-	/**
-	 * Refuse to load parent of GenesisBlock from DB!
-	 * <p>
-	 * As the genesis block is the first block, this always returns null.
-	 * 
-	 * @return null
-	 * @throws SQLException
-	 */
-	@Override
-	public Block getParent() throws SQLException {
-		return null;
-	}
-
-	// Converters
-
 	// Processing
 
 	@Override
-	public boolean addTransaction(TransactionHandler transaction) {
+	public boolean addTransaction(TransactionData transactionData) {
 		// The genesis block has a fixed set of transactions so always refuse.
 		return false;
 	}
 
 	private void addGenesisTransaction(String recipient, String amount) {
-		this.transactions.add(new GenesisTransaction(recipient, new BigDecimal(amount).setScale(8), this.timestamp));
+		this.transactions
+				.add(Transaction.fromData(new GenesisTransactionData(recipient, new BigDecimal(amount).setScale(8), this.getBlockData().getTimestamp())));
+		this.blockData.setTransactionCount(this.blockData.getTransactionCount() + 1);
 	}
 
 	/**
@@ -288,7 +246,7 @@ public class GenesisBlock extends Block {
 		try {
 			// Passing expected size to ByteArrayOutputStream avoids reallocation when adding more bytes than default 32.
 			// See below for explanation of some of the values used to calculated expected size.
-			ByteArrayOutputStream bytes = new ByteArrayOutputStream(8 + 64 + GENERATING_BALANCE_LENGTH + GENERATOR_LENGTH);
+			ByteArrayOutputStream bytes = new ByteArrayOutputStream(8 + 64 + 8 + 32);
 
 			/*
 			 * NOTE: Historic code had genesis block using Longs.toByteArray() compared to standard block's Ints.toByteArray. The subsequent
@@ -306,7 +264,7 @@ public class GenesisBlock extends Block {
 			bytes.write(Longs.toByteArray(GENESIS_GENERATING_BALANCE.longValue()));
 
 			// NOTE: Genesis account's public key is only 8 bytes, not the usual 32, so we have to pad.
-			bytes.write(Bytes.ensureCapacity(GENESIS_GENERATOR.getPublicKey(), 32, 0));
+			bytes.write(Bytes.ensureCapacity(GENESIS_GENERATOR_PUBLIC_KEY, 32, 0));
 
 			return bytes.toByteArray();
 		} catch (IOException e) {
@@ -317,25 +275,25 @@ public class GenesisBlock extends Block {
 	@Override
 	public boolean isSignatureValid() {
 		// Validate block signature
-		if (!Arrays.equals(GENESIS_GENERATOR_SIGNATURE, this.generatorSignature))
+		if (!Arrays.equals(GENESIS_GENERATOR_SIGNATURE, this.getBlockData().getGeneratorSignature()))
 			return false;
 
 		// Validate transactions signature
-		if (!Arrays.equals(GENESIS_TRANSACTIONS_SIGNATURE, this.transactionsSignature))
+		if (!Arrays.equals(GENESIS_TRANSACTIONS_SIGNATURE, this.getBlockData().getTransactionsSignature()))
 			return false;
 
 		return true;
 	}
 
 	@Override
-	public boolean isValid() throws SQLException {
+	public boolean isValid() throws DataException {
 		// Check there is no other block in DB
-		if (BlockChain.getHeight() != 0)
+		if (this.repository.getBlockRepository().getBlockchainHeight() != 0)
 			return false;
 
 		// Validate transactions
-		for (TransactionHandler transaction : this.getTransactions())
+		for (Transaction transaction : this.getTransactions())
-			if (transaction.isValid() != TransactionHandler.ValidationResult.OK)
+			if (transaction.isValid() != Transaction.ValidationResult.OK)
 				return false;
 
 		return true;

src/qora/transaction/Transaction.java

@@ -12,6 +12,7 @@ import data.transaction.TransactionData;
 import qora.account.PrivateKeyAccount;
 import qora.block.Block;
 import qora.block.BlockChain;
+import repository.Repository;
 import repository.RepositoryManager;
 import settings.Settings;
 import transform.TransformationException;
@@ -63,26 +64,27 @@ public abstract class Transaction {
 	protected static final BigDecimal maxBytePerFee = BigDecimal.valueOf(Settings.getInstance().getMaxBytePerFee());
 	protected static final BigDecimal minFeePerByte = BigDecimal.ONE.divide(maxBytePerFee, MathContext.DECIMAL32);
 
+	// Properties
 	protected TransactionData transactionData;
-	
+
 	// Constructors
 
 	public static Transaction fromData(TransactionData transactionData) {
 		switch (transactionData.getType()) {
 			case GENESIS:
 				return new GenesisTransaction(transactionData);
-				
+
 			default:
 				return null;
 		}
 	}
 
 	// Getters / Setters
-	
+
 	public TransactionData getTransactionData() {
 		return this.transactionData;
 	}
-	
+
 	// More information
 
 	public long getDeadline() {
@@ -108,17 +110,18 @@ public abstract class Transaction {
 
 	public BigDecimal calcRecommendedFee() {
 		try {
-			BigDecimal recommendedFee = BigDecimal.valueOf(TransactionTransformer.getDataLength(this.transactionData)).divide(maxBytePerFee, MathContext.DECIMAL32).setScale(8);
+			BigDecimal recommendedFee = BigDecimal.valueOf(TransactionTransformer.getDataLength(this.transactionData))
-	
+					.divide(maxBytePerFee, MathContext.DECIMAL32).setScale(8);
+
 			// security margin
 			recommendedFee = recommendedFee.add(new BigDecimal("0.0000001"));
-	
+
 			if (recommendedFee.compareTo(MINIMUM_FEE) <= 0) {
 				recommendedFee = MINIMUM_FEE;
 			} else {
 				recommendedFee = recommendedFee.setScale(0, BigDecimal.ROUND_UP);
 			}
-	
+
 			return recommendedFee.setScale(8);
 		} catch (TransformationException e) {
 			throw new IllegalStateException("Unable to get transaction byte length?");
@@ -139,7 +142,7 @@ public abstract class Transaction {
 	 * @return height, or 0 if not in blockchain (i.e. unconfirmed)
 	 */
 	public int getHeight() {
-		return RepositoryManager.getTransactionRepository().getHeight(this.transactionData);
+		return RepositoryManager.getRepository().getTransactionRepository().getHeight(this.transactionData);
 	}
 
 	/**
@@ -148,14 +151,14 @@ public abstract class Transaction {
 	 * @return confirmation count, or 0 if not in blockchain (i.e. unconfirmed)
 	 */
 	public int getConfirmations() {
-		int ourHeight = this.getHeight();
+		int ourHeight = getHeight();
 		if (ourHeight == 0)
 			return 0;
 
 		int blockChainHeight = BlockChain.getHeight();
 		if (blockChainHeight == 0)
 			return 0;
-		
+
 		return blockChainHeight - ourHeight + 1;
 	}
 

src/repository/BlockRepository.java

@@ -14,6 +14,22 @@ public interface BlockRepository {
 
 	public BlockData fromHeight(int height) throws DataException;
 
+	/**
+	 * Return height of block in blockchain using block's signature.
+	 * 
+	 * @param signature
+	 * @return height, or 0 if not found in blockchain.
+	 * @throws DataException
+	 */
+	public int getHeightFromSignature(byte[] signature) throws DataException;
+
+	/**
+	 * Return highest block height from DB.
+	 * 
+	 * @return height, or 0 if there are no blocks in DB (not very likely).
+	 */
+	public int getBlockchainHeight() throws DataException;
+
 	public List<TransactionData> getTransactionsFromSignature(byte[] signature) throws DataException;
 
 	public void save(BlockData blockData) throws DataException;

src/repository/Repository.java

@@ -14,4 +14,6 @@ public interface Repository {
 
 	public void close() throws DataException;
 
+	public void rebuild() throws DataException;
+
 }

src/repository/hsqldb/HSQLDBBlockRepository.java

@@ -25,6 +25,31 @@ public class HSQLDBBlockRepository implements BlockRepository {
 		this.repository = repository;
 	}
 
+	private BlockData getBlockFromResultSet(ResultSet rs) throws DataException {
+		if (rs == null)
+			return null;
+
+		try {
+			int version = rs.getInt(1);
+			byte[] reference = this.repository.getResultSetBytes(rs.getBinaryStream(2));
+			int transactionCount = rs.getInt(3);
+			BigDecimal totalFees = rs.getBigDecimal(4);
+			byte[] transactionsSignature = this.repository.getResultSetBytes(rs.getBinaryStream(5));
+			int height = rs.getInt(6);
+			long timestamp = rs.getTimestamp(7).getTime();
+			BigDecimal generatingBalance = rs.getBigDecimal(8);
+			byte[] generatorPublicKey = this.repository.getResultSetBytes(rs.getBinaryStream(9));
+			byte[] generatorSignature = this.repository.getResultSetBytes(rs.getBinaryStream(10));
+			byte[] atBytes = this.repository.getResultSetBytes(rs.getBinaryStream(11));
+			BigDecimal atFees = rs.getBigDecimal(12);
+
+			return new BlockData(version, reference, transactionCount, totalFees, transactionsSignature, height, timestamp, generatingBalance,
+					generatorPublicKey, generatorSignature, atBytes, atFees);
+		} catch (SQLException e) {
+			throw new DataException("Error extracting data from result set", e);
+		}
+	}
+
 	public BlockData fromSignature(byte[] signature) throws DataException {
 		try {
 			ResultSet rs = this.repository.checkedExecute("SELECT " + BLOCK_DB_COLUMNS + " FROM Blocks WHERE signature = ?", signature);
@@ -52,28 +77,27 @@ public class HSQLDBBlockRepository implements BlockRepository {
 		}
 	}
 
-	private BlockData getBlockFromResultSet(ResultSet rs) throws DataException {
+	public int getHeightFromSignature(byte[] signature) throws DataException {
-		if (rs == null)
-			return null;
-
 		try {
-			int version = rs.getInt(1);
+			ResultSet rs = this.repository.checkedExecute("SELECT height FROM Blocks WHERE signature = ?", signature);
-			byte[] reference = this.repository.getResultSetBytes(rs.getBinaryStream(2));
+			if (rs == null)
-			int transactionCount = rs.getInt(3);
+				return 0;
-			BigDecimal totalFees = rs.getBigDecimal(4);
-			byte[] transactionsSignature = this.repository.getResultSetBytes(rs.getBinaryStream(5));
-			int height = rs.getInt(6);
-			long timestamp = rs.getTimestamp(7).getTime();
-			BigDecimal generatingBalance = rs.getBigDecimal(8);
-			byte[] generatorPublicKey = this.repository.getResultSetBytes(rs.getBinaryStream(9));
-			byte[] generatorSignature = this.repository.getResultSetBytes(rs.getBinaryStream(10));
-			byte[] atBytes = this.repository.getResultSetBytes(rs.getBinaryStream(11));
-			BigDecimal atFees = rs.getBigDecimal(12);
 
-			return new BlockData(version, reference, transactionCount, totalFees, transactionsSignature, height, timestamp, generatingBalance,
+			return rs.getInt(1);
-					generatorPublicKey, generatorSignature, atBytes, atFees);
 		} catch (SQLException e) {
-			throw new DataException("Error extracting data from result set", e);
+			throw new DataException("Error obtaining block height from repository", e);
+		}
+	}
+
+	public int getBlockchainHeight() throws DataException {
+		try {
+			ResultSet rs = this.repository.checkedExecute("SELECT MAX(height) FROM Blocks");
+			if (rs == null)
+				return 0;
+
+			return rs.getInt(1);
+		} catch (SQLException e) {
+			throw new DataException("Error obtaining blockchain height from repository", e);
 		}
 	}
 

src/repository/hsqldb/HSQLDBRepository.java

@@ -69,6 +69,10 @@ public class HSQLDBRepository implements Repository {
 		}
 	}
 
+	@Override
+	public void rebuild() throws DataException {
+	}
+
 	/**
 	 * Convert InputStream, from ResultSet.getBinaryStream(), into byte[].
 	 * 

src/transform/block/BlockTransformer.java

@@ -210,7 +210,7 @@ public class BlockTransformer extends Transformer {
 		json.put("version", blockData.getVersion());
 		json.put("timestamp", blockData.getTimestamp());
 		json.put("generatingBalance", blockData.getGeneratingBalance());
-		json.put("generator", new PublicKeyAccount(blockData.getGeneratorPublicKey()).getAddress());
+		json.put("generator", PublicKeyAccount.getAddress(blockData.getGeneratorPublicKey()));
 		json.put("generatorPublicKey", Base58.encode(blockData.getGeneratorPublicKey()));
 		json.put("fee", blockData.getTotalFees().toPlainString());
 		json.put("transactionsSignature", Base58.encode(blockData.getTransactionsSignature()));