@Override
    protected void startUp() throws Exception {
        // Runs in a separate thread.
        if (!directory.exists()) {
            if (!directory.mkdir()) {
                throw new IOException("Could not create named directory.");
            }
        }
        FileInputStream walletStream = null;
        try {
            File chainFile = new File(directory, filePrefix + ".spvchain");
            boolean chainFileExists = chainFile.exists();
            vWalletFile = new File(directory, filePrefix + ".wallet");
            boolean shouldReplayWallet = vWalletFile.exists() && !chainFileExists;

            vStore = new SPVBlockStore(params, chainFile);
            if (!chainFileExists && checkpoints != null) {
                // Ugly hack! We have to create the wallet once here to learn the earliest key time, and then throw it
                // away. The reason is that wallet extensions might need access to peergroups/chains/etc so we have to
                // create the wallet later, but we need to know the time early here before we create the BlockChain
                // object.
                long time = Long.MAX_VALUE;
                if (vWalletFile.exists()) {
                    Wallet wallet = new Wallet(params);
                    FileInputStream stream = new FileInputStream(vWalletFile);
                    new WalletProtobufSerializer().readWallet(WalletProtobufSerializer.parseToProto(stream), wallet);
                    time = wallet.getEarliestKeyCreationTime();
                }
                CheckpointManager.checkpoint(params, checkpoints, vStore, time);
            }
            vChain = new BlockChain(params, vStore);
            vPeerGroup = new PeerGroup(params, vChain);
            if (this.userAgent != null)
                vPeerGroup.setUserAgent(userAgent, version);
            if (vWalletFile.exists()) {
                walletStream = new FileInputStream(vWalletFile);
                vWallet = new Wallet(params);
                addWalletExtensions(); // All extensions must be present before we deserialize
                new WalletProtobufSerializer().readWallet(WalletProtobufSerializer.parseToProto(walletStream), vWallet);
                if (shouldReplayWallet)
                    vWallet.clearTransactions(0);
            } else {
                vWallet = new Wallet(params);
                vWallet.addKey(new ECKey());
                addWalletExtensions();
            }
            if (useAutoSave) vWallet.autosaveToFile(vWalletFile, 1, TimeUnit.SECONDS, null);
            // Set up peer addresses or discovery first, so if wallet extensions try to broadcast a transaction
            // before we're actually connected the broadcast waits for an appropriate number of connections.
            if (peerAddresses != null) {
                for (PeerAddress addr : peerAddresses) vPeerGroup.addAddress(addr);
                peerAddresses = null;
            } else {
                vPeerGroup.addPeerDiscovery(new DnsDiscovery(params));
            }
            vChain.addWallet(vWallet);
            vPeerGroup.addWallet(vWallet);
            onSetupCompleted();

            if (blockingStartup) {
                vPeerGroup.startAndWait();
                // Make sure we shut down cleanly.
                installShutdownHook();
                // TODO: Be able to use the provided download listener when doing a blocking startup.
                final DownloadListener listener = new DownloadListener();
                vPeerGroup.startBlockChainDownload(listener);
                listener.await();
            } else {
                Futures.addCallback(vPeerGroup.start(), new FutureCallback<State>() {
                    @Override
                    public void onSuccess(State result) {
                        final PeerEventListener l = downloadListener == null ? new DownloadListener() : downloadListener;
                        vPeerGroup.startBlockChainDownload(l);
                    }

                    @Override
                    public void onFailure(Throwable t) {
                        throw new RuntimeException(t);
                    }
                });
            }
        } catch (BlockStoreException e) {
            throw new IOException(e);
        } finally {
            if (walletStream != null) walletStream.close();
        }
    }