Created a test for the Synchronizer.

Not passing yet.

bulletin-board-client/src/main/java/meerkat/bulletinboard/SimpleBulletinBoardClient.java

@@ -1,22 +1,13 @@
 package meerkat.bulletinboard;
 
 import com.google.protobuf.ByteString;
-import com.google.protobuf.Timestamp;
 import meerkat.bulletinboard.workers.singleserver.*;
 import meerkat.comm.CommunicationException;
-import meerkat.comm.MessageInputStream;
-import meerkat.crypto.Digest;
 import meerkat.crypto.concrete.SHA256Digest;
-import meerkat.protobuf.BulletinBoardAPI;
 import meerkat.protobuf.BulletinBoardAPI.*;
 import meerkat.protobuf.Voting.*;
 import meerkat.rest.*;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.lang.reflect.InvocationTargetException;
-import java.util.Collection;
-import java.util.Iterator;
 import java.util.List;
 
 import javax.ws.rs.client.Client;
@@ -68,7 +59,7 @@ public class SimpleBulletinBoardClient implements BulletinBoardClient{
     public MessageID postMessage(BulletinBoardMessage msg) throws CommunicationException {
 
         WebTarget webTarget;
-        Response response;
+        Response response = null;
 
         // Post message to all databases
         try {
@@ -80,10 +71,17 @@ public class SimpleBulletinBoardClient implements BulletinBoardClient{
                 if (response.getStatusInfo() == Response.Status.OK
                         || response.getStatusInfo() == Response.Status.CREATED) {
                     response.readEntity(BoolMsg.class).getValue();
+                } else {
+                    throw new CommunicationException("Server returned error. Status was: " + response.getStatus());
                 }
             }
         } catch (Exception e) { // Occurs only when server replies with valid status but invalid data
-            throw new CommunicationException("Error accessing database: " + e.getMessage());
+
+            throw new CommunicationException("Server returned invalid data type: " + e.getMessage());
+
+        } finally {
+            if (response != null)
+                response.close();
         }
 
         // Calculate the correct message ID and return it
@@ -100,36 +98,33 @@ public class SimpleBulletinBoardClient implements BulletinBoardClient{
         int batchID = completeBatch.getBeginBatchMessage().getBatchId();
 
         // Post message to all databases
-        try {
-            for (String db : meerkatDBs) {
 
-                SingleServerBeginBatchWorker beginBatchWorker = new SingleServerBeginBatchWorker(db, completeBatch.getBeginBatchMessage(), 0);
+        for (String db : meerkatDBs) {
 
-                beginBatchWorker.call();
+            SingleServerBeginBatchWorker beginBatchWorker = new SingleServerBeginBatchWorker(db, completeBatch.getBeginBatchMessage(), 0);
 
-                BatchMessage.Builder builder = BatchMessage.newBuilder().setSignerId(signerID).setBatchId(batchID);
+            beginBatchWorker.call();
 
-                for (BatchData batchData : completeBatch.getBatchDataList()) {
+            BatchMessage.Builder builder = BatchMessage.newBuilder().setSignerId(signerID).setBatchId(batchID);
 
-                    SingleServerPostBatchWorker postBatchWorker =
+            for (BatchData batchData : completeBatch.getBatchDataList()) {
-                            new SingleServerPostBatchWorker(
-                                    db,
-                                    builder.setData(batchData).setSerialNum(pos).build(),
-                                    0);
 
-                    postBatchWorker.call();
+                SingleServerPostBatchWorker postBatchWorker =
+                        new SingleServerPostBatchWorker(
+                                db,
+                                builder.setData(batchData).setSerialNum(pos).build(),
+                                0);
 
-                    pos++;
+                postBatchWorker.call();
 
-                }
+                pos++;
-
-                SingleServerCloseBatchWorker closeBatchWorker = new SingleServerCloseBatchWorker(db, completeBatch.getCloseBatchMessage(), 0);
-
-                closeBatchWorker.call();
 
             }
-        } catch (Exception e) { // Occurs only when server replies with valid status but invalid data
+
-            throw new CommunicationException("Error accessing database: " + e.getMessage());
+            SingleServerCloseBatchWorker closeBatchWorker = new SingleServerCloseBatchWorker(db, completeBatch.getCloseBatchMessage(), 0);
+
+            closeBatchWorker.call();
+
         }
 
         digest.update(completeBatch);

bulletin-board-client/src/main/java/meerkat/bulletinboard/SimpleBulletinBoardSynchronizer.java

@@ -8,6 +8,8 @@ import meerkat.util.BulletinBoardUtils;
 
 import java.util.LinkedList;
 import java.util.List;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Created by Arbel on 13/04/2016.
@@ -25,24 +27,75 @@ public class SimpleBulletinBoardSynchronizer implements BulletinBoardSynchronize
 
     private static final MessageFilterList EMPTY_FILTER = MessageFilterList.getDefaultInstance();
     private static final int SLEEP_INTERVAL = 10000; // 10 Seconds
+    private static final int WAIT_CAP = 300000; // 5 minutes wait before deciding that the sync has failed fatally
 
+    private Semaphore semaphore;
+
+    /**
+     * This class is a callback that deletes a message if it has been successfully posted
+     * It also calls a stored callback
+     */
     private class MessageDeleteCallback implements FutureCallback<Boolean> {
 
         private final long entryNum;
+        private final FutureCallback<Void> callback;
 
-        public MessageDeleteCallback(long entryNum) {
+        public MessageDeleteCallback(long entryNum, FutureCallback<Void> callback) {
             this.entryNum = entryNum;
+            this.callback = callback;
         }
 
         @Override
         public void onSuccess(Boolean result) {
             // Success: delete from database
             localClient.deleteMessage(entryNum, null);
+            callback.onSuccess(null);
         }
 
         @Override
         public void onFailure(Throwable t) {
-            // Ignore
+            callback.onFailure(t);
+        }
+
+    }
+
+    /**
+     * This class aggregates the results from all of the post operations
+     * If any post has failed: it changes the sync status to SERVER_ERROR
+     * It also notifies the main sync loop when all uploads are finished
+     */
+    private class SyncStatusUpdateCallback implements FutureCallback<Void> {
+
+        private int count;
+        private boolean errorEncountered;
+
+        public SyncStatusUpdateCallback(int count) {
+            this.count = count;
+            this.errorEncountered = false;
+        }
+
+        private void handleStatusUpdate() {
+            count--;
+            if (count <= 0) {
+
+                if (errorEncountered)
+                    updateSyncStatus(SyncStatus.SERVER_ERROR);
+
+                // Upload is done: wake up the synchronizer loop
+                semaphore.release();
+
+            }
+        }
+
+        @Override
+        public void onSuccess(Void result) {
+            handleStatusUpdate();
+        }
+
+        @Override
+        public void onFailure(Throwable t) {
+            errorEncountered = true;
+            handleStatusUpdate();
         }
 
     }
@@ -52,6 +105,20 @@ public class SimpleBulletinBoardSynchronizer implements BulletinBoardSynchronize
         @Override
         public void onSuccess(List<BulletinBoardMessage> result) {
 
+            // Notify Message Count callbacks if needed
+
+            if (syncStatus != SyncStatus.SYNCHRONIZED || result.size() > 0) {
+
+                for (FutureCallback<Integer> callback : messageCountCallbacks){
+                    callback.onSuccess(result.size());
+                }
+
+            }
+
+            // Handle upload and status change
+
+            SyncStatusUpdateCallback syncStatusUpdateCallback = new SyncStatusUpdateCallback(result.size());
+
             SyncStatus newStatus = SyncStatus.PENDING;
 
             if (result.size() == 0) {
@@ -79,20 +146,21 @@ public class SimpleBulletinBoardSynchronizer implements BulletinBoardSynchronize
 
                             CompleteBatch completeBatch = localClient.readBatch(batchSpecificationMessage);
 
-                            remoteClient.postBatch(completeBatch);
+                            remoteClient.postBatch(completeBatch, new MessageDeleteCallback(message.getEntryNum(), syncStatusUpdateCallback));
 
 
                         } else {
 
                             // This is a regular message: post it
-
+                            remoteClient.postMessage(message, new MessageDeleteCallback(message.getEntryNum(), syncStatusUpdateCallback));
-                            remoteClient.postMessage(message);
 
                         }
 
                         localClient.deleteMessage(message.getEntryNum());
 
                     } catch (CommunicationException e) {
+                        // This is an error with the local server
+                        // TODO: log
                         updateSyncStatus(SyncStatus.SERVER_ERROR);
                     }
 
@@ -143,6 +211,8 @@ public class SimpleBulletinBoardSynchronizer implements BulletinBoardSynchronize
         messageCountCallbacks = new LinkedList<>();
         syncStatusCallbacks = new LinkedList<>();
 
+        semaphore = new Semaphore(0);
+
     }
 
     @Override
@@ -185,18 +255,32 @@ public class SimpleBulletinBoardSynchronizer implements BulletinBoardSynchronize
 
             while (syncStatus != SyncStatus.STOPPED) {
 
-                try {
+                do {
+
+                    if (syncStatus == SyncStatus.PENDING || syncStatus == SyncStatus.SERVER_ERROR) {
 
-                    do {
                         localClient.readMessages(EMPTY_FILTER, callback);
-                    } while (syncStatus == SyncStatus.PENDING);
 
-                    synchronized (this) {
-                        this.wait(SLEEP_INTERVAL);
                     }
 
+                    try {
+
+                        semaphore.tryAcquire(WAIT_CAP, TimeUnit.MILLISECONDS);
+                        //TODO: log hard error. Too much time trying to upload data.
+
+                    } catch (InterruptedException ignored) {
+                        // We expect an interruption when the upload will complete
+                    }
+
+
+                } while (syncStatus == SyncStatus.PENDING);
+
+                // Database is synced. Wait for new data.
+
+                try {
+                    semaphore.tryAcquire(SLEEP_INTERVAL, TimeUnit.MILLISECONDS);
                 } catch (InterruptedException e) {
-                    e.printStackTrace();
+                    //TODO: log (probably nudged)
                 }
 
             }
@@ -207,9 +291,7 @@ public class SimpleBulletinBoardSynchronizer implements BulletinBoardSynchronize
 
     @Override
     public void nudge() {
-        synchronized (this) {
+        semaphore.release();
-            this.notify();
-        }
     }
 
     @Override

bulletin-board-client/src/main/java/meerkat/bulletinboard/workers/singleserver/SingleServerGetRedundancyWorker.java

@@ -6,7 +6,6 @@ import meerkat.comm.MessageInputStream;
 import meerkat.protobuf.BulletinBoardAPI.*;
 import meerkat.rest.Constants;
 
-import javax.ws.rs.ProcessingException;
 import javax.ws.rs.client.Client;
 import javax.ws.rs.client.Entity;
 import javax.ws.rs.client.WebTarget;
@@ -14,7 +13,6 @@ import javax.ws.rs.core.Response;
 
 import java.io.IOException;
 import java.io.InputStream;
-import java.lang.reflect.InvocationTargetException;
 
 import static meerkat.bulletinboard.BulletinBoardConstants.BULLETIN_BOARD_SERVER_PATH;
 import static meerkat.bulletinboard.BulletinBoardConstants.READ_MESSAGES_PATH;

bulletin-board-client/src/test/java/meerkat/bulletinboard/BulletinBoardSynchronizerTest.java

@@ -0,0 +1,241 @@
+package meerkat.bulletinboard;
+
+import com.google.common.util.concurrent.FutureCallback;
+import com.google.protobuf.ByteString;
+
+import static meerkat.bulletinboard.BulletinBoardSynchronizer.SyncStatus;
+
+import meerkat.bulletinboard.sqlserver.BulletinBoardSQLServer;
+import meerkat.bulletinboard.sqlserver.H2QueryProvider;
+
+import meerkat.comm.CommunicationException;
+import meerkat.crypto.concrete.ECDSASignature;
+import meerkat.protobuf.BulletinBoardAPI.*;
+import meerkat.util.BulletinBoardMessageComparator;
+import meerkat.util.BulletinBoardMessageGenerator;
+import org.junit.*;
+import org.springframework.jdbc.core.RowMapper;
+import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.security.*;
+import java.security.cert.CertificateException;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.Semaphore;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.fail;
+
+/**
+ * Created by Arbel on 6/1/2016.
+ */
+public class BulletinBoardSynchronizerTest {
+
+    private static final String REMOTE_SERVER_ADDRESS = "remoteDB";
+    private static final String LOCAL_SERVER_ADDRESS = "localDB";
+
+    private static final int THREAD_NUM = 3;
+    private static final int SUBSCRIPTION_INTERVAL = 1000;
+
+    private DeletableSubscriptionBulletinBoardClient localClient;
+    private AsyncBulletinBoardClient remoteClient;
+
+    private BulletinBoardSynchronizer synchronizer;
+
+    private static BulletinBoardMessageGenerator messageGenerator;
+    private static BulletinBoardMessageComparator messageComparator;
+
+    private static String KEYFILE_EXAMPLE = "/certs/enduser-certs/user1-key-with-password-secret.p12";
+    private static String KEYFILE_PASSWORD1 = "secret";
+    private static String CERT1_PEM_EXAMPLE = "/certs/enduser-certs/user1.crt";
+
+    private static GenericBatchDigitalSignature[] signers;
+    private static ByteString[] signerIDs;
+
+    private Semaphore semaphore;
+    private List<Throwable> thrown;
+
+    @BeforeClass
+    public static void build() {
+
+        messageGenerator = new BulletinBoardMessageGenerator(new Random(0));
+        messageComparator = new BulletinBoardMessageComparator();
+
+        signers = new GenericBatchDigitalSignature[1];
+        signerIDs = new ByteString[1];
+
+        signers[0] = new GenericBatchDigitalSignature(new ECDSASignature());
+
+        InputStream keyStream = BulletinBoardSynchronizerTest.class.getResourceAsStream(KEYFILE_EXAMPLE);
+        char[] password = KEYFILE_PASSWORD1.toCharArray();
+
+        try {
+
+            KeyStore.Builder keyStoreBuilder = signers[0].getPKCS12KeyStoreBuilder(keyStream, password);
+
+            signers[0].loadSigningCertificate(keyStoreBuilder);
+
+            signers[0].loadVerificationCertificates(BulletinBoardSynchronizerTest.class.getResourceAsStream(CERT1_PEM_EXAMPLE));
+
+        } catch (IOException e) {
+            System.err.println("Failed reading from signature file " + e.getMessage());
+            fail("Failed reading from signature file " + e.getMessage());
+        } catch (CertificateException e) {
+            System.err.println("Failed reading certificate " + e.getMessage());
+            fail("Failed reading certificate " + e.getMessage());
+        } catch (KeyStoreException e) {
+            System.err.println("Failed reading keystore " + e.getMessage());
+            fail("Failed reading keystore " + e.getMessage());
+        } catch (NoSuchAlgorithmException e) {
+            System.err.println("Couldn't find signing algorithm " + e.getMessage());
+            fail("Couldn't find signing algorithm " + e.getMessage());
+        } catch (UnrecoverableKeyException e) {
+            System.err.println("Couldn't find signing key " + e.getMessage());
+            fail("Couldn't find signing key " + e.getMessage());
+        }
+
+        signerIDs[0] = signers[0].getSignerID();
+
+    }
+
+    @Before
+    public void init() throws CommunicationException {
+
+        DeletableBulletinBoardServer remoteServer = new BulletinBoardSQLServer(new H2QueryProvider(REMOTE_SERVER_ADDRESS));
+        remoteServer.init(REMOTE_SERVER_ADDRESS);
+
+        remoteClient = new LocalBulletinBoardClient(
+                remoteServer,
+                THREAD_NUM,
+                SUBSCRIPTION_INTERVAL);
+
+        DeletableBulletinBoardServer localServer = new BulletinBoardSQLServer(new H2QueryProvider(LOCAL_SERVER_ADDRESS));
+        localServer.init(LOCAL_SERVER_ADDRESS);
+
+        localClient = new LocalBulletinBoardClient(
+                localServer,
+                THREAD_NUM,
+                SUBSCRIPTION_INTERVAL);
+
+        synchronizer = new SimpleBulletinBoardSynchronizer();
+        synchronizer.init(localClient, remoteClient);
+
+        semaphore = new Semaphore(0);
+        thrown = new LinkedList<>();
+
+    }
+
+    private class SyncStatusCallback implements FutureCallback<SyncStatus> {
+
+        @Override
+        public void onSuccess(SyncStatus result) {
+
+            if (result == SyncStatus.SYNCHRONIZED){
+                semaphore.release();
+            }
+
+        }
+
+        @Override
+        public void onFailure(Throwable t) {
+            thrown.add(t);
+            semaphore.release();
+        }
+    }
+
+    private class MessageCountCallback implements FutureCallback<Integer> {
+
+        private int[] expectedCounts;
+        private int currentIteration;
+
+        public MessageCountCallback(int[] expectedCounts) {
+            this.expectedCounts = expectedCounts;
+            this.currentIteration = 0;
+        }
+
+        @Override
+        public void onSuccess(Integer result) {
+
+            if (currentIteration < expectedCounts.length){
+                if (result != expectedCounts[currentIteration]){
+                    onFailure(new AssertionError("Wrong message count. Expected " + expectedCounts[currentIteration] + " but received " + result));
+                    currentIteration = expectedCounts.length;
+                    return;
+                }
+            }
+
+            currentIteration++;
+
+            if (currentIteration == expectedCounts.length)
+                semaphore.release();
+        }
+
+        @Override
+        public void onFailure(Throwable t) {
+            thrown.add(t);
+            semaphore.release();
+        }
+    }
+
+    @Test
+    public void testSync() throws SignatureException, CommunicationException, InterruptedException {
+
+        final int BATCH_ID = 1;
+
+        BulletinBoardMessage msg = messageGenerator.generateRandomMessage(signers, 10, 10);
+
+        MessageID msgID = localClient.postMessage(msg);
+
+        CompleteBatch completeBatch = messageGenerator.generateRandomBatch(signers[0],BATCH_ID,10,10,10);
+
+        localClient.postBatch(completeBatch);
+
+        synchronizer.subscribeToSyncStatus(new SyncStatusCallback());
+
+        int[] expectedCounts = {2,0};
+        synchronizer.subscribeToRemainingMessagesCount(new MessageCountCallback(expectedCounts));
+
+        Thread t = new Thread(synchronizer);
+        t.run();
+
+        semaphore.acquire();
+
+        synchronizer.stop();
+        t.join();
+
+        assertThat("Exception thrown by Synchronizer: " + thrown.get(0).getMessage(), thrown.size() == 0);
+
+        List<BulletinBoardMessage> msgList = remoteClient.readMessages(MessageFilterList.newBuilder()
+                .addFilter(MessageFilter.newBuilder()
+                        .setType(FilterType.MSG_ID)
+                        .setId(msgID.getID())
+                        .build())
+                .build());
+
+        assertThat("Wrong number of messages returned.", msgList.size() == 1);
+        assertThat("Returned message is not equal to original one", messageComparator.compare(msgList.get(0),msg) == 0);
+
+        CompleteBatch returnedBatch = remoteClient.readBatch(BatchSpecificationMessage.newBuilder()
+                .setSignerId(signerIDs[0])
+                .setBatchId(BATCH_ID)
+                .build());
+
+        assertThat("Returned batch does not equal original one.", completeBatch.equals(returnedBatch));
+
+    }
+
+    @After
+    public void close() {
+
+        synchronizer.stop();
+        localClient.close();
+        remoteClient.close();
+
+    }
+
+}

bulletin-board-server/src/main/java/meerkat/bulletinboard/sqlserver/BulletinBoardSQLServer.java

@@ -6,7 +6,6 @@ import java.util.*;
 import com.google.protobuf.*;
 
 import com.google.protobuf.Timestamp;
-import com.sun.org.apache.xpath.internal.operations.Bool;
 import meerkat.bulletinboard.*;
 import meerkat.bulletinboard.sqlserver.mappers.*;
 import static meerkat.bulletinboard.BulletinBoardConstants.*;
@@ -17,7 +16,6 @@ import meerkat.comm.MessageOutputStream;
 import meerkat.crypto.concrete.ECDSASignature;
 import meerkat.crypto.concrete.SHA256Digest;
 
-import meerkat.protobuf.BulletinBoardAPI;
 import meerkat.protobuf.BulletinBoardAPI.*;
 import meerkat.protobuf.Crypto.Signature;
 import meerkat.protobuf.Crypto.SignatureVerificationKey;
@@ -29,7 +27,6 @@ import javax.sql.DataSource;
 
 import meerkat.util.BulletinBoardUtils;
 import meerkat.util.TimestampComparator;
-import org.springframework.jdbc.core.RowMapper;
 import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
 import org.springframework.jdbc.support.GeneratedKeyHolder;

bulletin-board-server/src/main/java/meerkat/bulletinboard/sqlserver/H2QueryProvider.java

@@ -247,12 +247,12 @@ public class H2QueryProvider implements BulletinBoardSQLServer.SQLQueryProvider
         list.add("CREATE TABLE IF NOT EXISTS TagTable (TagId INT NOT NULL AUTO_INCREMENT PRIMARY KEY, Tag VARCHAR(50) UNIQUE)");
 
         list.add("CREATE TABLE IF NOT EXISTS MsgTagTable (EntryNum INT, TagId INT,"
-                + " FOREIGN KEY (EntryNum) REFERENCES MsgTable(EntryNum),"
+                + " FOREIGN KEY (EntryNum) REFERENCES MsgTable(EntryNum) ON DELETE CASCADE,"
-                + " FOREIGN KEY (TagId) REFERENCES TagTable(TagId),"
+                + " FOREIGN KEY (TagId) REFERENCES TagTable(TagId) ON DELETE CASCADE,"
                 + " UNIQUE (EntryNum, TagID))");
 
         list.add("CREATE TABLE IF NOT EXISTS SignatureTable (EntryNum INT, SignerId TINYBLOB, Signature TINYBLOB UNIQUE,"
-                + " FOREIGN KEY (EntryNum) REFERENCES MsgTable(EntryNum))");
+                + " FOREIGN KEY (EntryNum) REFERENCES MsgTable(EntryNum) ON DELETE CASCADE)");
 
         list.add("CREATE INDEX IF NOT EXISTS SignerIndex ON SignatureTable(SignerId)");
         list.add("CREATE UNIQUE INDEX IF NOT EXISTS SignerIndex ON SignatureTable(SignerId, EntryNum)");
@@ -261,7 +261,7 @@ public class H2QueryProvider implements BulletinBoardSQLServer.SQLQueryProvider
                 + " UNIQUE(SignerId, BatchId, SerialNum))");
 
         list.add("CREATE TABLE IF NOT EXISTS BatchTagTable (SignerId TINYBLOB, BatchId INT, TagId INT,"
-                + " FOREIGN KEY (TagId) REFERENCES TagTable(TagId))");
+                + " FOREIGN KEY (TagId) REFERENCES TagTable(TagId) ON DELETE CASCADE)");
 
         list.add("CREATE INDEX IF NOT EXISTS BatchIndex ON BatchTagTable(SignerId, BatchId)");
 

meerkat-common/src/main/java/meerkat/bulletinboard/BulletinBoardSynchronizer.java

@@ -16,8 +16,8 @@ public interface BulletinBoardSynchronizer extends Runnable {
 
     public enum SyncStatus{
         SYNCHRONIZED,   // No more messages to upload
-        PENDING,        // Synchronizer is uploading data
+        PENDING,        // Synchronizer is querying for data to upload and uploading it as needed
-        SERVER_ERROR,   // Synchronizer encountered an error while uploading
+        SERVER_ERROR,   // Synchronizer encountered an error while uploading, but will retry
         STOPPED         // Stopped/Not started by user
     }
 

meerkat-common/src/main/java/meerkat/util/BulletinBoardMessageGenerator.java

@@ -1,13 +1,14 @@
 package meerkat.util;
 
 import com.google.protobuf.ByteString;
+import meerkat.bulletinboard.BatchDigitalSignature;
+import meerkat.bulletinboard.CompleteBatch;
 import meerkat.crypto.DigitalSignature;
 import meerkat.protobuf.BulletinBoardAPI.*;
 import com.google.protobuf.Timestamp;
 
 import java.math.BigInteger;
 import java.security.SignatureException;
-import java.util.Arrays;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Random;
@@ -28,10 +29,33 @@ public class BulletinBoardMessageGenerator {
         return (byte) random.nextInt();
     }
 
+    private byte[] randomBytes(int length) {
+
+        byte[] result = new byte[length];
+
+        for (int i = 0; i < length; i++) {
+            result[i] = randomByte();
+        }
+
+        return result;
+    }
+
     private String randomString(){
         return new BigInteger(130, random).toString(32);
     }
 
+    private List<String> randomStrings(int length) {
+
+        List<String> result = new LinkedList<>();
+
+        for (int i = 0; i < length; i++) {
+            result.add(randomString());
+        }
+
+        return result;
+
+    }
+
     /**
      * Generates a complete instance of a BulletinBoardMessage
      * @param signers contains the (possibly multiple) credentials required to sign the message
@@ -46,23 +70,16 @@ public class BulletinBoardMessageGenerator {
 
         // Generate random data.
 
-        byte[] data = new byte[dataSize];
-        String[] newTags = new String[tagNumber];
 
-        for (int i = 0; i < dataSize; i++) {
-            data[i] = randomByte();
-        }
 
-        for (int i = 0; i < tagNumber; i++) {
+
-            newTags[i] = randomString();
-        }
 
         UnsignedBulletinBoardMessage unsignedMessage =
                 UnsignedBulletinBoardMessage.newBuilder()
-                        .setData(ByteString.copyFrom(data))
+                        .setData(ByteString.copyFrom(randomBytes(dataSize)))
                         .setTimestamp(timestamp)
                         .addAllTag(tags)
-                        .addAllTag(Arrays.asList(newTags))
+                        .addAllTag(randomStrings(tagNumber))
                         .build();
 
         BulletinBoardMessage.Builder messageBuilder =
@@ -102,7 +119,6 @@ public class BulletinBoardMessageGenerator {
      * @param tagNumber is the number of tags to generate
      * @return a random, signed Bulletin Board Message containing random data, tags and timestamp
      */
-
     public BulletinBoardMessage generateRandomMessage(DigitalSignature[] signers, int dataSize, int tagNumber)
             throws SignatureException {
 
@@ -115,4 +131,97 @@ public class BulletinBoardMessageGenerator {
 
     }
 
+    /**
+     * Generates a complete instance of a CompleteBatch
+     * @param signer contains the credentials required to sign the message
+     * @param batchId is the (per-signer) batch-ID
+     * @param timestamp is the time at which the message was generated
+     * @param dataCount is the number of Batch Data in the batch
+     * @param dataSize is the number of bytes per Batch Data
+     * @param tagCount is the number of tags
+     * @param tags contains a list of tags to be added (in addition to the random ones)
+     * @return a random, signed CompleteBatch containing random data and tags
+     * @throws SignatureException if an error occurs while signing the batch
+     */
+    public CompleteBatch generateRandomBatch(BatchDigitalSignature signer, int batchId, Timestamp timestamp, int dataCount, int dataSize, int tagCount, List<String> tags) throws SignatureException {
+
+        CompleteBatch result = new CompleteBatch(BeginBatchMessage.newBuilder()
+                .setSignerId(signer.getSignerID())
+                .setBatchId(batchId)
+                .addAllTag(tags)
+                .addAllTag(randomStrings(tagCount))
+                .build());
+
+        List<BatchData> batchDataList = new LinkedList<>();
+
+        for (int i = 0 ; i < dataCount ; i++) {
+            batchDataList.add(BatchData.newBuilder()
+                    .setData(ByteString.copyFrom(randomBytes(dataSize)))
+                    .build());
+        }
+
+        result.appendBatchData(batchDataList);
+
+        result.setTimestamp(timestamp);
+
+        signer.updateContent(result);
+
+        result.setSignature(signer.sign());
+
+        return result;
+
+    }
+
+    /**
+     * Generates a complete instance of a CompleteBatch
+     * @param signer contains the credentials required to sign the message
+     * @param batchId is the (per-signer) batch-ID
+     * @param timestamp is the time at which the message was generated
+     * @param dataCount is the number of Batch Data in the batch
+     * @param dataSize is the number of bytes per Batch Data
+     * @param tagCount is the number of tags
+     * @return a random, signed CompleteBatch containing random data and tags
+     * @throws SignatureException if an error occurs while signing the batch
+     */
+    public CompleteBatch generateRandomBatch(BatchDigitalSignature signer, int batchId, Timestamp timestamp, int dataCount, int dataSize, int tagCount) throws SignatureException {
+        return generateRandomBatch(signer, batchId, timestamp, dataCount, dataSize, tagCount, new LinkedList<String>());
+    }
+
+
+    /**
+     * Generates a complete instance of a CompleteBatch
+     * @param signer contains the credentials required to sign the message
+     * @param batchId is the (per-signer) batch-ID
+     * @param dataCount is the number of Batch Data in the batch
+     * @param dataSize is the number of bytes per Batch Data
+     * @param tagCount is the number of tags
+     * @param tags contains a list of tags to be added (in addition to the random ones)
+     * @return a random, signed CompleteBatch containing random data, tags and timestamp
+     * @throws SignatureException if an error occurs while signing the batch
+     */
+    public CompleteBatch generateRandomBatch(BatchDigitalSignature signer, int batchId, int dataCount, int dataSize, int tagCount, List<String> tags) throws SignatureException {
+
+        Timestamp timestamp = Timestamp.newBuilder()
+                .setSeconds(random.nextLong())
+                .setNanos(random.nextInt())
+                .build();
+
+        return generateRandomBatch(signer, batchId, timestamp, dataCount, dataSize, tagCount, tags);
+
+    }
+
+    /**
+     * Generates a complete instance of a CompleteBatch
+     * @param signer contains the credentials required to sign the message
+     * @param batchId is the (per-signer) batch-ID
+     * @param dataCount is the number of Batch Data in the batch
+     * @param dataSize is the number of bytes per Batch Data
+     * @param tagCount is the number of tags
+     * @return a random, signed CompleteBatch containing random data, tags and timestamp
+     * @throws SignatureException if an error occurs while signing the batch
+     */
+    public CompleteBatch generateRandomBatch(BatchDigitalSignature signer, int batchId, int dataCount, int dataSize, int tagCount) throws SignatureException {
+        return generateRandomBatch(signer, batchId, dataCount, dataSize, tagCount, new LinkedList<String>());
+    }
+
 }