Refactor the Introduction Client to avoid circular dependencies

This injects the IntroducerManager and the IntroduceeManger for easier testing

briar-api/src/org/briarproject/api/introduction/IntroductionManager.java

@@ -45,22 +45,4 @@ public interface IntroductionManager {
 	Collection<IntroductionMessage> getIntroductionMessages(ContactId contactId)
 			throws DbException;
 
-	/** Marks an introduction message as read or unread. */
-	void setReadFlag(MessageId m, boolean read) throws DbException;
-
-
-	/** Get the session state for the given session ID */
-	BdfDictionary getSessionState(Transaction txn, GroupId groupId,
-			byte[] sessionId) throws DbException, FormatException;
-
-	/** Gets the group used for introductions with Contact c */
-	Group getIntroductionGroup(Contact c);
-
-	/** Get the local group used to store session states */
-	Group getLocalGroup();
-
-	/** Send an introduction message */
-	void sendMessage(Transaction txn, BdfDictionary message)
-			throws DbException, FormatException;
-
 }

briar-core/src/org/briarproject/introduction/IntroduceeManager.java

@@ -24,11 +24,8 @@ import org.briarproject.api.event.IntroductionSucceededEvent;
 import org.briarproject.api.identity.Author;
 import org.briarproject.api.identity.AuthorFactory;
 import org.briarproject.api.identity.AuthorId;
-import org.briarproject.api.introduction.IntroductionManager;
-import org.briarproject.api.introduction.SessionId;
 import org.briarproject.api.properties.TransportProperties;
 import org.briarproject.api.properties.TransportPropertyManager;
-import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.MessageId;
@@ -40,6 +37,8 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.logging.Logger;
 
+import javax.inject.Inject;
+
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.api.introduction.IntroduceeProtocolState.AWAIT_REQUEST;
 import static org.briarproject.api.introduction.IntroductionConstants.ACCEPT;
@@ -76,33 +75,36 @@ import static org.briarproject.api.introduction.IntroductionConstants.TYPE_RESPO
 
 class IntroduceeManager {
 
-
 	private static final Logger LOG =
 			Logger.getLogger(IntroduceeManager.class.getName());
 
+	private final MessageSender messageSender;
 	private final DatabaseComponent db;
-	private final IntroductionManager introductionManager;
 	private final ClientHelper clientHelper;
 	private final Clock clock;
 	private final CryptoComponent cryptoComponent;
 	private final TransportPropertyManager transportPropertyManager;
 	private final AuthorFactory authorFactory;
 	private final ContactManager contactManager;
+	private final IntroductionGroupFactory introductionGroupFactory;
 
-	IntroduceeManager(DatabaseComponent db,
-			IntroductionManager introductionManager, ClientHelper clientHelper,
-			Clock clock, CryptoComponent cryptoComponent,
+	@Inject
+	IntroduceeManager(MessageSender messageSender, DatabaseComponent db,
+			ClientHelper clientHelper, Clock clock,
+			CryptoComponent cryptoComponent,
 			TransportPropertyManager transportPropertyManager,
-			AuthorFactory authorFactory, ContactManager contactManager) {
+			AuthorFactory authorFactory, ContactManager contactManager,
+			IntroductionGroupFactory introductionGroupFactory) {
 
+		this.messageSender = messageSender;
 		this.db = db;
-		this.introductionManager = introductionManager;
 		this.clientHelper = clientHelper;
 		this.clock = clock;
 		this.cryptoComponent = cryptoComponent;
 		this.transportPropertyManager = transportPropertyManager;
 		this.authorFactory = authorFactory;
 		this.contactManager = contactManager;
+		this.introductionGroupFactory = introductionGroupFactory;
 	}
 
 	public BdfDictionary initialize(Transaction txn, GroupId groupId,
@@ -113,9 +115,9 @@ class IntroduceeManager {
 		Bytes salt = new Bytes(new byte[64]);
 		cryptoComponent.getSecureRandom().nextBytes(salt.getBytes());
 
-		Message localMsg = clientHelper
-				.createMessage(introductionManager.getLocalGroup().getId(), now,
-						BdfList.of(salt));
+		Message localMsg = clientHelper.createMessage(
+				introductionGroupFactory.createLocalGroup().getId(), now,
+				BdfList.of(salt));
 		MessageId storageId = localMsg.getId();
 
 		// find out who is introducing us
@@ -133,7 +135,7 @@ class IntroduceeManager {
 		d.put(INTRODUCER, introducer.getAuthor().getName());
 		d.put(CONTACT_ID_1, introducer.getId().getInt());
 		d.put(LOCAL_AUTHOR_ID, introducer.getLocalAuthorId().getBytes());
-		d.put(NOT_OUR_RESPONSE, new byte[0]);
+		d.put(NOT_OUR_RESPONSE, storageId);
 		d.put(ANSWERED, false);
 
 		// check if the contact we are introduced to does already exist
@@ -147,7 +149,7 @@ class IntroduceeManager {
 
 		// save local state to database
 		clientHelper.addLocalMessage(txn, localMsg,
-				introductionManager.getClientId(), d, false);
+				IntroductionManagerImpl.CLIENT_ID, d, false);
 
 		return d;
 	}
@@ -159,16 +161,10 @@ class IntroduceeManager {
 		processStateUpdate(txn, engine.onMessageReceived(state, message));
 	}
 
-	public void acceptIntroduction(Transaction txn, final ContactId contactId,
-			final SessionId sessionId, final long timestamp)
+	public void acceptIntroduction(Transaction txn, BdfDictionary state,
+			final long timestamp)
 			throws DbException, FormatException {
 
-		Contact c = db.getContact(txn, contactId);
-		Group g = introductionManager.getIntroductionGroup(c);
-
-		BdfDictionary state = introductionManager
-				.getSessionState(txn, g.getId(), sessionId.getBytes());
-
 		// get data to connect and derive a shared secret later
 		long now = clock.currentTimeMillis();
 		KeyPair keyPair = cryptoComponent.generateAgreementKeyPair();
@@ -195,16 +191,10 @@ class IntroduceeManager {
 		processStateUpdate(txn, engine.onLocalAction(state, localAction));
 	}
 
-	public void declineIntroduction(Transaction txn, final ContactId contactId,
-			final SessionId sessionId, final long timestamp)
+	public void declineIntroduction(Transaction txn, BdfDictionary state,
+			final long timestamp)
 			throws DbException, FormatException {
 
-		Contact c = db.getContact(txn, contactId);
-		Group g = introductionManager.getIntroductionGroup(c);
-
-		BdfDictionary state = introductionManager
-				.getSessionState(txn, g.getId(), sessionId.getBytes());
-
 		// update session state
 		state.put(ACCEPT, false);
 
@@ -233,7 +223,7 @@ class IntroduceeManager {
 
 		// send messages
 		for (BdfDictionary d : result.toSend) {
-			introductionManager.sendMessage(txn, d);
+			messageSender.sendMessage(txn, d);
 		}
 
 		// broadcast events

briar-core/src/org/briarproject/introduction/IntroducerManager.java

@@ -10,7 +10,6 @@ import org.briarproject.api.data.BdfList;
 import org.briarproject.api.db.DbException;
 import org.briarproject.api.db.Transaction;
 import org.briarproject.api.event.Event;
-import org.briarproject.api.introduction.IntroductionManager;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.MessageId;
@@ -20,6 +19,8 @@ import org.briarproject.util.StringUtils;
 import java.io.IOException;
 import java.util.logging.Logger;
 
+import javax.inject.Inject;
+
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.api.introduction.IntroducerProtocolState.PREPARE_REQUESTS;
 import static org.briarproject.api.introduction.IntroductionConstants.AUTHOR_ID_1;
@@ -39,7 +40,6 @@ import static org.briarproject.api.introduction.IntroductionConstants.ROLE_INTRO
 import static org.briarproject.api.introduction.IntroductionConstants.SESSION_ID;
 import static org.briarproject.api.introduction.IntroductionConstants.STATE;
 import static org.briarproject.api.introduction.IntroductionConstants.STORAGE_ID;
-import static org.briarproject.api.introduction.IntroductionConstants.TIME;
 import static org.briarproject.api.introduction.IntroductionConstants.TYPE;
 import static org.briarproject.api.introduction.IntroductionConstants.TYPE_ABORT;
 import static org.briarproject.api.introduction.IntroductionConstants.TYPE_REQUEST;
@@ -49,19 +49,22 @@ class IntroducerManager {
 	private static final Logger LOG =
 		Logger.getLogger(IntroducerManager.class.getName());
 
-	private final IntroductionManager introductionManager;
+	private final MessageSender messageSender;
 	private final ClientHelper clientHelper;
 	private final Clock clock;
 	private final CryptoComponent cryptoComponent;
+	private final IntroductionGroupFactory introductionGroupFactory;
 
-	IntroducerManager(IntroductionManager introductionManager,
-			ClientHelper clientHelper, Clock clock,
-			CryptoComponent cryptoComponent) {
+	@Inject
+	IntroducerManager(MessageSender messageSender, ClientHelper clientHelper,
+			Clock clock, CryptoComponent cryptoComponent,
+			IntroductionGroupFactory introductionGroupFactory) {
 
-		this.introductionManager = introductionManager;
+		this.messageSender = messageSender;
 		this.clientHelper = clientHelper;
 		this.clock = clock;
 		this.cryptoComponent = cryptoComponent;
+		this.introductionGroupFactory = introductionGroupFactory;
 	}
 
 	public BdfDictionary initialize(Transaction txn, Contact c1, Contact c2)
@@ -72,13 +75,13 @@ class IntroducerManager {
 		Bytes salt = new Bytes(new byte[64]);
 		cryptoComponent.getSecureRandom().nextBytes(salt.getBytes());
 
-		Message m = clientHelper
-				.createMessage(introductionManager.getLocalGroup().getId(), now,
-						BdfList.of(salt));
+		Message m = clientHelper.createMessage(
+				introductionGroupFactory.createLocalGroup().getId(), now,
+				BdfList.of(salt));
 		MessageId sessionId = m.getId();
 
-		Group g1 = introductionManager.getIntroductionGroup(c1);
-		Group g2 = introductionManager.getIntroductionGroup(c2);
+		Group g1 = introductionGroupFactory.createIntroductionGroup(c1);
+		Group g2 = introductionGroupFactory.createIntroductionGroup(c2);
 
 		BdfDictionary d = new BdfDictionary();
 		d.put(SESSION_ID, sessionId);
@@ -95,7 +98,9 @@ class IntroducerManager {
 		d.put(AUTHOR_ID_2, c2.getAuthor().getId());
 
 		// save local state to database
-		clientHelper.addLocalMessage(txn, m, introductionManager.getClientId(), d, false);
+		clientHelper
+				.addLocalMessage(txn, m, IntroductionManagerImpl.CLIENT_ID, d,
+						false);
 
 		return d;
 	}
@@ -143,7 +148,7 @@ class IntroducerManager {
 
 		// send messages
 		for (BdfDictionary d : result.toSend) {
-			introductionManager.sendMessage(txn, d);
+			messageSender.sendMessage(txn, d);
 		}
 
 		// broadcast events

briar-core/src/org/briarproject/introduction/IntroductionGroupFactory.java

@@ -0,0 +1,30 @@
+package org.briarproject.introduction;
+
+import org.briarproject.api.clients.PrivateGroupFactory;
+import org.briarproject.api.contact.Contact;
+import org.briarproject.api.sync.Group;
+
+import javax.inject.Inject;
+
+class IntroductionGroupFactory {
+
+	final private PrivateGroupFactory privateGroupFactory;
+	final private Group localGroup;
+
+	@Inject
+	IntroductionGroupFactory(PrivateGroupFactory privateGroupFactory) {
+		this.privateGroupFactory = privateGroupFactory;
+		localGroup = privateGroupFactory
+				.createLocalGroup(IntroductionManagerImpl.CLIENT_ID);
+	}
+
+	public Group createIntroductionGroup(Contact c) {
+		return privateGroupFactory
+				.createPrivateGroup(IntroductionManagerImpl.CLIENT_ID, c);
+	}
+
+	public Group createLocalGroup() {
+		return localGroup;
+	}
+
+}

briar-core/src/org/briarproject/introduction/IntroductionManagerImpl.java

@@ -3,25 +3,17 @@ package org.briarproject.introduction;
 import org.briarproject.api.FormatException;
 import org.briarproject.api.clients.Client;
 import org.briarproject.api.clients.ClientHelper;
-import org.briarproject.api.clients.MessageQueueManager;
-import org.briarproject.api.clients.PrivateGroupFactory;
 import org.briarproject.api.contact.Contact;
 import org.briarproject.api.contact.ContactId;
-import org.briarproject.api.contact.ContactManager;
 import org.briarproject.api.contact.ContactManager.AddContactHook;
 import org.briarproject.api.contact.ContactManager.RemoveContactHook;
-import org.briarproject.api.crypto.CryptoComponent;
 import org.briarproject.api.data.BdfDictionary;
-import org.briarproject.api.data.BdfEntry;
 import org.briarproject.api.data.BdfList;
-import org.briarproject.api.data.MetadataEncoder;
 import org.briarproject.api.data.MetadataParser;
 import org.briarproject.api.db.DatabaseComponent;
 import org.briarproject.api.db.DbException;
-import org.briarproject.api.db.Metadata;
 import org.briarproject.api.db.NoSuchMessageException;
 import org.briarproject.api.db.Transaction;
-import org.briarproject.api.identity.AuthorFactory;
 import org.briarproject.api.identity.AuthorId;
 import org.briarproject.api.introduction.IntroducerProtocolState;
 import org.briarproject.api.introduction.IntroductionManager;
@@ -29,7 +21,6 @@ import org.briarproject.api.introduction.IntroductionMessage;
 import org.briarproject.api.introduction.IntroductionRequest;
 import org.briarproject.api.introduction.IntroductionResponse;
 import org.briarproject.api.introduction.SessionId;
-import org.briarproject.api.properties.TransportPropertyManager;
 import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
@@ -94,37 +85,22 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 			Logger.getLogger(IntroductionManagerImpl.class.getName());
 
 	private final DatabaseComponent db;
-	private final MessageQueueManager messageQueueManager;
-	private final PrivateGroupFactory privateGroupFactory;
-	private final MetadataEncoder metadataEncoder;
 	private final IntroducerManager introducerManager;
 	private final IntroduceeManager introduceeManager;
-	private final Group localGroup;
+	private final IntroductionGroupFactory introductionGroupFactory;
 
 	@Inject
-	IntroductionManagerImpl(DatabaseComponent db,
-			MessageQueueManager messageQueueManager,
-			ClientHelper clientHelper, PrivateGroupFactory privateGroupFactory,
-			MetadataEncoder metadataEncoder, MetadataParser metadataParser,
-			CryptoComponent cryptoComponent,
-			TransportPropertyManager transportPropertyManager,
-			AuthorFactory authorFactory, ContactManager contactManager,
-			Clock clock) {
+	IntroductionManagerImpl(DatabaseComponent db, ClientHelper clientHelper,
+			MetadataParser metadataParser, Clock clock,
+			IntroducerManager introducerManager,
+			IntroduceeManager introduceeManager,
+			IntroductionGroupFactory introductionGroupFactory) {
 
 		super(clientHelper, metadataParser, clock);
 		this.db = db;
-		this.messageQueueManager = messageQueueManager;
-		this.privateGroupFactory = privateGroupFactory;
-		this.metadataEncoder = metadataEncoder;
-		// TODO: Inject these dependencies for easier testing
-		this.introducerManager =
-				new IntroducerManager(this, clientHelper, clock,
-						cryptoComponent);
-		this.introduceeManager =
-				new IntroduceeManager(db, this, clientHelper, clock,
-						cryptoComponent, transportPropertyManager,
-						authorFactory, contactManager);
-		localGroup = privateGroupFactory.createLocalGroup(CLIENT_ID);
+		this.introducerManager = introducerManager;
+		this.introduceeManager = introduceeManager;
+		this.introductionGroupFactory = introductionGroupFactory;
 	}
 
 	@Override
@@ -134,7 +110,7 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 
 	@Override
 	public void createLocalState(Transaction txn) throws DbException {
-		db.addGroup(txn, localGroup);
+		db.addGroup(txn, introductionGroupFactory.createLocalGroup());
 		// Ensure we've set things up for any pre-existing contacts
 		for (Contact c : db.getContacts(txn)) addingContact(txn, c);
 	}
@@ -143,7 +119,7 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 	public void addingContact(Transaction txn, Contact c) throws DbException {
 		try {
 			// Create an introduction group for sending introduction messages
-			Group g = getIntroductionGroup(c);
+			Group g = introductionGroupFactory.createIntroductionGroup(c);
 			// Return if we've already set things up for this contact
 			if (db.containsGroup(txn, g.getId())) return;
 			// Store the group and share it with the contact
@@ -164,7 +140,8 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 		Long id = (long) c.getId().getInt();
 		try {
 			Map<MessageId, BdfDictionary> map = clientHelper
-					.getMessageMetadataAsDictionary(txn, localGroup.getId());
+					.getMessageMetadataAsDictionary(txn,
+							introductionGroupFactory.createLocalGroup().getId());
 			for (Map.Entry<MessageId, BdfDictionary> entry : map.entrySet()) {
 				BdfDictionary d = entry.getValue();
 				long role = d.getLong(ROLE, -1L);
@@ -185,7 +162,7 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 
 		// remove the group (all messages will be removed with it)
 		// this contact won't get our abort message, but the other will
-		db.removeGroup(txn, getIntroductionGroup(c));
+		db.removeGroup(txn, introductionGroupFactory.createIntroductionGroup(c));
 	}
 
 	/**
@@ -287,8 +264,12 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 
 		Transaction txn = db.startTransaction(false);
 		try {
-			introduceeManager
-					.acceptIntroduction(txn, contactId, sessionId, timestamp);
+			Contact c = db.getContact(txn, contactId);
+			Group g = introductionGroupFactory.createIntroductionGroup(c);
+			BdfDictionary state =
+					getSessionState(txn, g.getId(), sessionId.getBytes());
+
+			introduceeManager.acceptIntroduction(txn, state, timestamp);
 			txn.setComplete();
 		} finally {
 			db.endTransaction(txn);
@@ -302,8 +283,12 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 
 		Transaction txn = db.startTransaction(false);
 		try {
-			introduceeManager
-					.declineIntroduction(txn, contactId, sessionId, timestamp);
+			Contact c = db.getContact(txn, contactId);
+			Group g = introductionGroupFactory.createIntroductionGroup(c);
+			BdfDictionary state =
+					getSessionState(txn, g.getId(), sessionId.getBytes());
+
+			introduceeManager.declineIntroduction(txn, state, timestamp);
 			txn.setComplete();
 		} finally {
 			db.endTransaction(txn);
@@ -322,8 +307,9 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 		Transaction txn = db.startTransaction(true);
 		try {
 			// get messages and their status
-			GroupId g =
-					getIntroductionGroup(db.getContact(txn, contactId)).getId();
+			GroupId g = introductionGroupFactory
+					.createIntroductionGroup(db.getContact(txn, contactId))
+					.getId();
 			metadata = clientHelper.getMessageMetadataAsDictionary(txn, g);
 			statuses = db.getMessageStatus(txn, contactId, g);
 
@@ -444,17 +430,7 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 		}
 	}
 
-	@Override
-	public void setReadFlag(MessageId m, boolean read) throws DbException {
-		try {
-			BdfDictionary meta = BdfDictionary.of(new BdfEntry(READ, read));
-			clientHelper.mergeMessageMetadata(m, meta);
-		} catch (FormatException e) {
-			throw new RuntimeException(e);
-		}
-	}
-
-	public BdfDictionary getSessionState(Transaction txn, GroupId groupId,
+	private BdfDictionary getSessionState(Transaction txn, GroupId groupId,
 			byte[] sessionId) throws DbException, FormatException {
 
 		try {
@@ -473,7 +449,7 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 			// to find state for introducee
 			Map<MessageId, BdfDictionary> map = clientHelper
 					.getMessageMetadataAsDictionary(txn,
-							localGroup.getId());
+							introductionGroupFactory.createLocalGroup().getId());
 			for (Map.Entry<MessageId, BdfDictionary> m : map.entrySet()) {
 				if (Arrays.equals(m.getValue().getRaw(SESSION_ID), sessionId)) {
 					BdfDictionary state = m.getValue();
@@ -490,35 +466,11 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 		}
 	}
 
-	public Group getIntroductionGroup(Contact c) {
-		return privateGroupFactory.createPrivateGroup(CLIENT_ID, c);
-	}
-
-	public Group getLocalGroup() {
-		return localGroup;
-	}
-
-	public void sendMessage(Transaction txn, BdfDictionary message)
-			throws DbException, FormatException {
-
-		BdfList bdfList = MessageEncoder.encodeMessage(message);
-		byte[] body = clientHelper.toByteArray(bdfList);
-		GroupId groupId = new GroupId(message.getRaw(GROUP_ID));
-		Group group = db.getGroup(txn, groupId);
-		long timestamp =
-				message.getLong(MESSAGE_TIME, System.currentTimeMillis());
-		message.put(MESSAGE_TIME, timestamp);
-
-		Metadata metadata = metadataEncoder.encode(message);
-
-		messageQueueManager
-				.sendMessage(txn, group, timestamp, body, metadata);
-	}
-
 	private void deleteMessage(Transaction txn, MessageId messageId)
 			throws DbException {
 
 		db.deleteMessage(txn, messageId);
 		db.deleteMessageMetadata(txn, messageId);
 	}
+
 }

briar-core/src/org/briarproject/introduction/IntroductionModule.java

@@ -3,9 +3,13 @@ package org.briarproject.introduction;
 import org.briarproject.api.clients.ClientHelper;
 import org.briarproject.api.clients.MessageQueueManager;
 import org.briarproject.api.contact.ContactManager;
+import org.briarproject.api.crypto.CryptoComponent;
 import org.briarproject.api.data.MetadataEncoder;
+import org.briarproject.api.db.DatabaseComponent;
+import org.briarproject.api.identity.AuthorFactory;
 import org.briarproject.api.introduction.IntroductionManager;
 import org.briarproject.api.lifecycle.LifecycleManager;
+import org.briarproject.api.properties.TransportPropertyManager;
 import org.briarproject.api.system.Clock;
 
 import javax.inject.Inject;

briar-core/src/org/briarproject/introduction/MessageSender.java

@@ -1,11 +1,25 @@
 package org.briarproject.introduction;
 
 import org.briarproject.api.FormatException;
+import org.briarproject.api.clients.ClientHelper;
+import org.briarproject.api.clients.MessageQueueManager;
 import org.briarproject.api.data.BdfDictionary;
 import org.briarproject.api.data.BdfList;
+import org.briarproject.api.data.MetadataEncoder;
+import org.briarproject.api.db.DatabaseComponent;
+import org.briarproject.api.db.DbException;
+import org.briarproject.api.db.Metadata;
+import org.briarproject.api.db.Transaction;
+import org.briarproject.api.sync.Group;
+import org.briarproject.api.sync.GroupId;
+import org.briarproject.api.system.Clock;
+
+import javax.inject.Inject;
 
 import static org.briarproject.api.introduction.IntroductionConstants.ACCEPT;
 import static org.briarproject.api.introduction.IntroductionConstants.E_PUBLIC_KEY;
+import static org.briarproject.api.introduction.IntroductionConstants.GROUP_ID;
+import static org.briarproject.api.introduction.IntroductionConstants.MESSAGE_TIME;
 import static org.briarproject.api.introduction.IntroductionConstants.MSG;
 import static org.briarproject.api.introduction.IntroductionConstants.NAME;
 import static org.briarproject.api.introduction.IntroductionConstants.PUBLIC_KEY;
@@ -18,9 +32,43 @@ import static org.briarproject.api.introduction.IntroductionConstants.TYPE_ACK;
 import static org.briarproject.api.introduction.IntroductionConstants.TYPE_REQUEST;
 import static org.briarproject.api.introduction.IntroductionConstants.TYPE_RESPONSE;
 
-public class MessageEncoder {
+class MessageSender {
 
-	public static BdfList encodeMessage(BdfDictionary d)
+	final private DatabaseComponent db;
+	final private ClientHelper clientHelper;
+	final private Clock clock;
+	final private MetadataEncoder metadataEncoder;
+	final private MessageQueueManager messageQueueManager;
+
+	@Inject
+	MessageSender(DatabaseComponent db, ClientHelper clientHelper, Clock clock,
+			MetadataEncoder metadataEncoder,
+			MessageQueueManager messageQueueManager) {
+
+		this.db = db;
+		this.clientHelper = clientHelper;
+		this.clock = clock;
+		this.metadataEncoder = metadataEncoder;
+		this.messageQueueManager = messageQueueManager;
+	}
+
+	public void sendMessage(Transaction txn, BdfDictionary message)
+			throws DbException, FormatException {
+
+		BdfList bdfList = encodeMessage(message);
+		byte[] body = clientHelper.toByteArray(bdfList);
+		GroupId groupId = new GroupId(message.getRaw(GROUP_ID));
+		Group group = db.getGroup(txn, groupId);
+		long timestamp = clock.currentTimeMillis();
+
+		message.put(MESSAGE_TIME, timestamp);
+		Metadata metadata = metadataEncoder.encode(message);
+
+		messageQueueManager
+				.sendMessage(txn, group, timestamp, body, metadata);
+	}
+
+	private BdfList encodeMessage(BdfDictionary d)
 			throws FormatException {
 
 		BdfList body;
@@ -39,7 +87,7 @@ public class MessageEncoder {
 		return body;
 	}
 
-	private static BdfList encodeRequest(BdfDictionary d)
+	private BdfList encodeRequest(BdfDictionary d)
 			throws FormatException {
 		BdfList list = BdfList.of(TYPE_REQUEST, d.getRaw(SESSION_ID),
 				d.getString(NAME), d.getRaw(PUBLIC_KEY));
@@ -50,7 +98,7 @@ public class MessageEncoder {
 		return list;
 	}
 
-	private static BdfList encodeResponse(BdfDictionary d)
+	private BdfList encodeResponse(BdfDictionary d)
 			throws FormatException {
 		BdfList list = BdfList.of(TYPE_RESPONSE, d.getRaw(SESSION_ID),
 				d.getBoolean(ACCEPT));
@@ -64,11 +112,11 @@ public class MessageEncoder {
 		return list;
 	}
 
-	private static BdfList encodeAck(BdfDictionary d) throws FormatException {
+	private BdfList encodeAck(BdfDictionary d) throws FormatException {
 		return BdfList.of(TYPE_ACK, d.getRaw(SESSION_ID));
 	}
 
-	private static BdfList encodeAbort(BdfDictionary d) throws FormatException {
+	private BdfList encodeAbort(BdfDictionary d) throws FormatException {
 		return BdfList.of(TYPE_ABORT, d.getRaw(SESSION_ID));
 	}