Merge branch 'conversation-manager' into 'master'

Use ConversationManager for private message retrieval

See merge request briar/briar!912

briar-core/src/main/java/org/briarproject/briar/introduction/AbstractProtocolEngine.java

@@ -150,12 +150,12 @@ abstract class AbstractProtocolEngine<S extends Session>
 		AuthorId localAuthorId = identityManager.getLocalAuthor(txn).getId();
 		Contact c = contactManager.getContact(txn, sender, localAuthorId);
 		IntroductionResponse response =
-				new IntroductionResponse(s.getSessionId(), m.getMessageId(),
-						m.getGroupId(), s.getRole(), m.getTimestamp(), false,
-						false, false, false, otherAuthor.getName(),
-						m instanceof AcceptMessage);
+				new IntroductionResponse(m.getMessageId(), m.getGroupId(),
+						m.getTimestamp(), false, false, false, false,
+						s.getSessionId(), m instanceof AcceptMessage,
+						otherAuthor, s.getRole());
 		IntroductionResponseReceivedEvent e =
-				new IntroductionResponseReceivedEvent(c.getId(), response);
+				new IntroductionResponseReceivedEvent(response, c.getId());
 		txn.attach(e);
 	}
 

briar-core/src/main/java/org/briarproject/briar/introduction/IntroduceeProtocolEngine.java

@@ -41,7 +41,6 @@ import javax.inject.Inject;
 
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.briar.api.introduction.Role.INTRODUCEE;
 import static org.briarproject.briar.introduction.IntroduceeState.AWAIT_AUTH;
 import static org.briarproject.briar.introduction.IntroduceeState.AWAIT_RESPONSES;
 import static org.briarproject.briar.introduction.IntroduceeState.LOCAL_ACCEPTED;
@@ -255,13 +254,12 @@ class IntroduceeProtocolEngine
 				localAuthor.getId());
 		boolean contactExists = contactManager
 				.contactExists(txn, m.getAuthor().getId(), localAuthor.getId());
-		IntroductionRequest request =
-				new IntroductionRequest(s.getSessionId(), m.getMessageId(),
-						m.getGroupId(), INTRODUCEE, m.getTimestamp(), false,
-						false, false, false, m.getAuthor().getName(), false,
-						m.getMessage(), false, contactExists);
+		IntroductionRequest request = new IntroductionRequest(m.getMessageId(),
+				m.getGroupId(), m.getTimestamp(), false, false, false, false,
+				s.getSessionId(), m.getAuthor(), m.getMessage(), false,
+				contactExists);
 		IntroductionRequestReceivedEvent e =
-				new IntroductionRequestReceivedEvent(c.getId(), request);
+				new IntroductionRequestReceivedEvent(request, c.getId());
 		txn.attach(e);
 
 		// Move to the AWAIT_RESPONSES state

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

@@ -30,10 +30,10 @@ import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVer
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.introduction.IntroductionManager;
-import org.briarproject.briar.api.introduction.IntroductionMessage;
 import org.briarproject.briar.api.introduction.IntroductionRequest;
 import org.briarproject.briar.api.introduction.IntroductionResponse;
 import org.briarproject.briar.api.introduction.Role;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.client.ConversationClientImpl;
 import org.briarproject.briar.introduction.IntroducerSession.Introducee;
 
@@ -398,17 +398,16 @@ class IntroductionManagerImpl extends ConversationClientImpl
 	}
 
 	@Override
-	public Collection<IntroductionMessage> getIntroductionMessages(ContactId c)
-			throws DbException {
-		List<IntroductionMessage> messages;
-		Transaction txn = db.startTransaction(true);
+	public Collection<PrivateMessageHeader> getMessageHeaders(Transaction txn,
+			ContactId c) throws DbException {
 		try {
 			Contact contact = db.getContact(txn, c);
 			GroupId contactGroupId = getContactGroup(contact).getId();
 			BdfDictionary query = messageParser.getMessagesVisibleInUiQuery();
 			Map<MessageId, BdfDictionary> results = clientHelper
 					.getMessageMetadataAsDictionary(txn, contactGroupId, query);
-			messages = new ArrayList<>(results.size());
+			List<PrivateMessageHeader> messages =
+					new ArrayList<>(results.size());
 			for (Entry<MessageId, BdfDictionary> e : results.entrySet()) {
 				MessageId m = e.getKey();
 				MessageMetadata meta =
@@ -431,13 +430,10 @@ class IntroductionManagerImpl extends ConversationClientImpl
 									status, ss.bdfSession, false));
 				}
 			}
-			db.commitTransaction(txn);
+			return messages;
 		} catch (FormatException e) {
 			throw new DbException(e);
-		} finally {
-			db.endTransaction(txn);
 		}
-		return messages;
 	}
 
 	private IntroductionRequest parseInvitationRequest(Transaction txn,
@@ -470,11 +466,9 @@ class IntroductionManagerImpl extends ConversationClientImpl
 		boolean contactExists = contactManager
 				.contactExists(txn, rm.getAuthor().getId(),
 						localAuthor.getId());
-
-		return new IntroductionRequest(sessionId, m, contactGroupId,
-				role, meta.getTimestamp(), meta.isLocal(),
-				status.isSent(), status.isSeen(), meta.isRead(),
-				author.getName(), false, message, !meta.isAvailableToAnswer(),
+		return new IntroductionRequest(m, contactGroupId, meta.getTimestamp(),
+				meta.isLocal(), status.isSent(), status.isSeen(), meta.isRead(),
+				sessionId, author, message, !meta.isAvailableToAnswer(),
 				contactExists);
 	}
 
@@ -499,9 +493,9 @@ class IntroductionManagerImpl extends ConversationClientImpl
 			sessionId = session.getSessionId();
 			author = session.getRemote().author;
 		} else throw new AssertionError();
-		return new IntroductionResponse(sessionId, m, contactGroupId,
-				role, meta.getTimestamp(), meta.isLocal(), status.isSent(),
-				status.isSeen(), meta.isRead(), author.getName(), accept);
+		return new IntroductionResponse(m, contactGroupId, meta.getTimestamp(),
+				meta.isLocal(), status.isSent(), status.isSeen(), meta.isRead(),
+				sessionId, accept, author, role);
 	}
 
 	private void removeSessionWithIntroducer(Transaction txn,

briar-core/src/main/java/org/briarproject/briar/messaging/ConversationManagerImpl.java

@@ -7,7 +7,11 @@ import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 import org.briarproject.briar.api.messaging.ConversationManager;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CopyOnWriteArraySet;
 
@@ -33,6 +37,22 @@ class ConversationManagerImpl implements ConversationManager {
 			throw new IllegalStateException("Client is already registered");
 	}
 
+	@Override
+	public Collection<PrivateMessageHeader> getMessageHeaders(ContactId c)
+			throws DbException {
+		List<PrivateMessageHeader> messages = new ArrayList<>();
+		Transaction txn = db.startTransaction(true);
+		try {
+			for (ConversationClient client : clients) {
+				messages.addAll(client.getMessageHeaders(txn, c));
+			}
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return messages;
+	}
+
 	@Override
 	public GroupCount getGroupCount(ContactId contactId) throws DbException {
 		int msgCount = 0, unreadCount = 0;

briar-core/src/main/java/org/briarproject/briar/messaging/MessagingManagerImpl.java

@@ -116,8 +116,8 @@ class MessagingManagerImpl extends ConversationClientImpl
 		PrivateMessageHeader header = new PrivateMessageHeader(
 				m.getId(), groupId, timestamp, local, read, false, false);
 		ContactId contactId = getContactId(txn, groupId);
-		PrivateMessageReceivedEvent event = new PrivateMessageReceivedEvent(
-				header, contactId, groupId);
+		PrivateMessageReceivedEvent<PrivateMessageHeader> event =
+				new PrivateMessageReceivedEvent<>(header, contactId);
 		txn.attach(event);
 		messageTracker.trackIncomingMessage(txn, m);
 
@@ -178,21 +178,17 @@ class MessagingManagerImpl extends ConversationClientImpl
 	}
 
 	@Override
-	public Collection<PrivateMessageHeader> getMessageHeaders(ContactId c)
-			throws DbException {
+	public Collection<PrivateMessageHeader> getMessageHeaders(Transaction txn,
+			ContactId c) throws DbException {
 		Map<MessageId, BdfDictionary> metadata;
 		Collection<MessageStatus> statuses;
 		GroupId g;
-		Transaction txn = db.startTransaction(true);
 		try {
 			g = getContactGroup(db.getContact(txn, c)).getId();
 			metadata = clientHelper.getMessageMetadataAsDictionary(txn, g);
 			statuses = db.getMessageStatus(txn, c, g);
-			db.commitTransaction(txn);
 		} catch (FormatException e) {
 			throw new DbException(e);
-		} finally {
-			db.endTransaction(txn);
 		}
 		Collection<PrivateMessageHeader> headers = new ArrayList<>();
 		for (MessageStatus s : statuses) {
@@ -203,9 +199,8 @@ class MessagingManagerImpl extends ConversationClientImpl
 				long timestamp = meta.getLong("timestamp");
 				boolean local = meta.getBoolean("local");
 				boolean read = meta.getBoolean("read");
-				headers.add(
-						new PrivateMessageHeader(id, g, timestamp, local, read,
-								s.isSent(), s.isSeen()));
+				headers.add(new PrivateMessageHeader(id, g, timestamp, local,
+						read, s.isSent(), s.isSeen()));
 			} catch (FormatException e) {
 				throw new DbException(e);
 			}

briar-core/src/main/java/org/briarproject/briar/privategroup/invitation/CreatorProtocolEngine.java

@@ -68,8 +68,7 @@ class CreatorProtocolEngine extends AbstractProtocolEngine<CreatorSession> {
 	}
 
 	@Override
-	public CreatorSession onJoinAction(Transaction txn, CreatorSession s)
-			throws DbException {
+	public CreatorSession onJoinAction(Transaction txn, CreatorSession s) {
 		throw new UnsupportedOperationException(); // Invalid in this role
 	}
 
@@ -91,8 +90,8 @@ class CreatorProtocolEngine extends AbstractProtocolEngine<CreatorSession> {
 	}
 
 	@Override
-	public CreatorSession onMemberAddedAction(Transaction txn, CreatorSession s)
-			throws DbException {
+	public CreatorSession onMemberAddedAction(Transaction txn,
+			CreatorSession s) {
 		return s; // Ignored in this role
 	}
 
@@ -193,8 +192,8 @@ class CreatorProtocolEngine extends AbstractProtocolEngine<CreatorSession> {
 		setPrivateGroupVisibility(txn, s, SHARED);
 		// Broadcast an event
 		ContactId contactId = getContactId(txn, m.getContactGroupId());
-		txn.attach(new GroupInvitationResponseReceivedEvent(contactId,
-				createInvitationResponse(m, contactId, true)));
+		txn.attach(new GroupInvitationResponseReceivedEvent(
+				createInvitationResponse(m, true), contactId));
 		// Move to the JOINED state
 		return new CreatorSession(s.getContactGroupId(), s.getPrivateGroupId(),
 				sent.getId(), m.getId(), sent.getTimestamp(),
@@ -215,8 +214,8 @@ class CreatorProtocolEngine extends AbstractProtocolEngine<CreatorSession> {
 				m.getTimestamp(), false);
 		// Broadcast an event
 		ContactId contactId = getContactId(txn, m.getContactGroupId());
-		txn.attach(new GroupInvitationResponseReceivedEvent(contactId,
-				createInvitationResponse(m, contactId, false)));
+		txn.attach(new GroupInvitationResponseReceivedEvent(
+				createInvitationResponse(m, false), contactId));
 		// Move to the START state
 		return new CreatorSession(s.getContactGroupId(), s.getPrivateGroupId(),
 				s.getLastLocalMessageId(), m.getId(), s.getLocalTimestamp(),
@@ -254,10 +253,10 @@ class CreatorProtocolEngine extends AbstractProtocolEngine<CreatorSession> {
 	}
 
 	private GroupInvitationResponse createInvitationResponse(
-			GroupInvitationMessage m, ContactId c, boolean accept) {
+			GroupInvitationMessage m, boolean accept) {
 		SessionId sessionId = new SessionId(m.getPrivateGroupId().getBytes());
 		return new GroupInvitationResponse(m.getId(), m.getContactGroupId(),
-				m.getTimestamp(), false, false, true, false, sessionId,
-				m.getPrivateGroupId(), c, accept);
+				m.getTimestamp(), false, false, false, false, sessionId,
+				accept, m.getPrivateGroupId());
 	}
 }

briar-core/src/main/java/org/briarproject/briar/privategroup/invitation/GroupInvitationManagerImpl.java

@@ -26,6 +26,7 @@ import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVersioningHook;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
 import org.briarproject.briar.api.privategroup.PrivateGroupFactory;
 import org.briarproject.briar.api.privategroup.PrivateGroupManager;
@@ -34,7 +35,6 @@ import org.briarproject.briar.api.privategroup.invitation.GroupInvitationItem;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationRequest;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
-import org.briarproject.briar.api.sharing.InvitationMessage;
 import org.briarproject.briar.client.ConversationClientImpl;
 
 import java.util.ArrayList;
@@ -353,7 +353,7 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 
 	private <S extends Session> S handleAction(Transaction txn,
 			LocalAction type, S session, ProtocolEngine<S> engine)
-			throws DbException, FormatException {
+			throws DbException {
 		if (type == LocalAction.INVITE) {
 			throw new IllegalArgumentException();
 		} else if (type == LocalAction.JOIN) {
@@ -368,17 +368,16 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 	}
 
 	@Override
-	public Collection<InvitationMessage> getInvitationMessages(ContactId c)
-			throws DbException {
-		List<InvitationMessage> messages;
-		Transaction txn = db.startTransaction(true);
+	public Collection<PrivateMessageHeader> getMessageHeaders(Transaction txn,
+			ContactId c) throws DbException {
 		try {
 			Contact contact = db.getContact(txn, c);
 			GroupId contactGroupId = getContactGroup(contact).getId();
 			BdfDictionary query = messageParser.getMessagesVisibleInUiQuery();
 			Map<MessageId, BdfDictionary> results = clientHelper
 					.getMessageMetadataAsDictionary(txn, contactGroupId, query);
-			messages = new ArrayList<>(results.size());
+			List<PrivateMessageHeader> messages =
+					new ArrayList<>(results.size());
 			for (Entry<MessageId, BdfDictionary> e : results.entrySet()) {
 				MessageId m = e.getKey();
 				MessageMetadata meta =
@@ -386,31 +385,25 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 				MessageStatus status = db.getMessageStatus(txn, c, m);
 				MessageType type = meta.getMessageType();
 				if (type == INVITE) {
-					messages.add(parseInvitationRequest(txn, c, contactGroupId,
-							m, meta, status));
+					messages.add(parseInvitationRequest(txn, contactGroupId, m,
+							meta, status));
 				} else if (type == JOIN) {
-					messages.add(
-							parseInvitationResponse(c, contactGroupId, m, meta,
-									status, true));
+					messages.add(parseInvitationResponse(contactGroupId, m,
+							meta, status, true));
 				} else if (type == LEAVE) {
-					messages.add(
-							parseInvitationResponse(c, contactGroupId, m, meta,
-									status, false));
+					messages.add(parseInvitationResponse(contactGroupId, m,
+							meta, status, false));
 				}
 			}
-			db.commitTransaction(txn);
+			return messages;
 		} catch (FormatException e) {
 			throw new DbException(e);
-		} finally {
-			db.endTransaction(txn);
 		}
-		return messages;
 	}
 
 	private GroupInvitationRequest parseInvitationRequest(Transaction txn,
-			ContactId c, GroupId contactGroupId, MessageId m,
-			MessageMetadata meta, MessageStatus status)
-			throws DbException, FormatException {
+			GroupId contactGroupId, MessageId m, MessageMetadata meta,
+			MessageStatus status) throws DbException, FormatException {
 		SessionId sessionId = getSessionId(meta.getPrivateGroupId());
 		// Look up the invite message to get the details of the private group
 		InviteMessage invite = messageParser.getInviteMessage(txn, m);
@@ -422,19 +415,19 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 				db.containsGroup(txn, invite.getPrivateGroupId());
 		return new GroupInvitationRequest(m, contactGroupId,
 				meta.getTimestamp(), meta.isLocal(), status.isSent(),
-				status.isSeen(), meta.isRead(), sessionId, pg, c,
+				status.isSeen(), meta.isRead(), sessionId, pg,
 				invite.getMessage(), meta.isAvailableToAnswer(), canBeOpened);
 	}
 
-	private GroupInvitationResponse parseInvitationResponse(ContactId c,
+	private GroupInvitationResponse parseInvitationResponse(
 			GroupId contactGroupId, MessageId m, MessageMetadata meta,
-			MessageStatus status, boolean accept)
-			throws DbException, FormatException {
+			MessageStatus status, boolean accept) {
 		SessionId sessionId = getSessionId(meta.getPrivateGroupId());
 		return new GroupInvitationResponse(m, contactGroupId,
 				meta.getTimestamp(), meta.isLocal(), status.isSent(),
-				status.isSeen(), meta.isRead(), sessionId,
-				meta.getPrivateGroupId(), c, accept);
+				status.isSeen(), meta.isRead(), sessionId, accept,
+				meta.getPrivateGroupId()
+		);
 	}
 
 	@Override

briar-core/src/main/java/org/briarproject/briar/privategroup/invitation/InviteeProtocolEngine.java

@@ -56,8 +56,7 @@ class InviteeProtocolEngine extends AbstractProtocolEngine<InviteeSession> {
 
 	@Override
 	public InviteeSession onInviteAction(Transaction txn, InviteeSession s,
-			@Nullable String message, long timestamp, byte[] signature)
-			throws DbException {
+			@Nullable String message, long timestamp, byte[] signature) {
 		throw new UnsupportedOperationException(); // Invalid in this role
 	}
 
@@ -99,8 +98,8 @@ class InviteeProtocolEngine extends AbstractProtocolEngine<InviteeSession> {
 	}
 
 	@Override
-	public InviteeSession onMemberAddedAction(Transaction txn, InviteeSession s)
-			throws DbException {
+	public InviteeSession onMemberAddedAction(Transaction txn,
+			InviteeSession s) {
 		return s; // Ignored in this role
 	}
 
@@ -244,9 +243,8 @@ class InviteeProtocolEngine extends AbstractProtocolEngine<InviteeSession> {
 		// Broadcast an event
 		PrivateGroup privateGroup = privateGroupFactory.createPrivateGroup(
 				m.getGroupName(), m.getCreator(), m.getSalt());
-		txn.attach(
-				new GroupInvitationRequestReceivedEvent(privateGroup, contactId,
-						createInvitationRequest(m, privateGroup, contactId)));
+		txn.attach(new GroupInvitationRequestReceivedEvent(
+				createInvitationRequest(m, privateGroup), contactId));
 		// Move to the INVITED state
 		return new InviteeSession(s.getContactGroupId(), s.getPrivateGroupId(),
 				s.getLastLocalMessageId(), m.getId(), s.getLocalTimestamp(),
@@ -328,10 +326,10 @@ class InviteeProtocolEngine extends AbstractProtocolEngine<InviteeSession> {
 	}
 
 	private GroupInvitationRequest createInvitationRequest(InviteMessage m,
-			PrivateGroup pg, ContactId c) {
+			PrivateGroup pg) {
 		SessionId sessionId = new SessionId(m.getPrivateGroupId().getBytes());
 		return new GroupInvitationRequest(m.getId(), m.getContactGroupId(),
-				m.getTimestamp(), false, false, true, false, sessionId, pg, c,
+				m.getTimestamp(), false, false, true, false, sessionId, pg,
 				m.getMessage(), true, false);
 	}
 

briar-core/src/main/java/org/briarproject/briar/sharing/BlogInvitationFactoryImpl.java

@@ -24,17 +24,16 @@ public class BlogInvitationFactoryImpl
 		SessionId sessionId = new SessionId(m.getShareableId().getBytes());
 		return new BlogInvitationRequest(m.getId(), m.getContactGroupId(),
 				m.getTimestamp(), local, sent, seen, read, sessionId,
-				m.getShareable(), c, m.getMessage(), available, canBeOpened);
+				m.getShareable(), m.getMessage(), available, canBeOpened);
 	}
 
 	@Override
 	public BlogInvitationResponse createInvitationResponse(MessageId id,
 			GroupId contactGroupId, long time, boolean local, boolean sent,
-			boolean seen, boolean read, GroupId shareableId,
-			ContactId contactId, boolean accept) {
+			boolean seen, boolean read, boolean accept, GroupId shareableId) {
 		SessionId sessionId = new SessionId(shareableId.getBytes());
-		return new BlogInvitationResponse(id, contactGroupId, time, local,
-				sent, seen, read, sessionId, shareableId, contactId, accept);
+		return new BlogInvitationResponse(id, contactGroupId, time, local, sent,
+				seen, read, sessionId, accept, shareableId);
 	}
 
 }

briar-core/src/main/java/org/briarproject/briar/sharing/BlogMessageParserImpl.java

@@ -30,7 +30,7 @@ class BlogMessageParserImpl extends MessageParserImpl<Blog> {
 	}
 
 	@Override
-	protected Blog createShareable(BdfList descriptor) throws FormatException {
+	public Blog createShareable(BdfList descriptor) throws FormatException {
 		// Author, RSS
 		BdfList authorList = descriptor.getList(0);
 		boolean rssFeed = descriptor.getBoolean(1);

briar-core/src/main/java/org/briarproject/briar/sharing/BlogProtocolEngineImpl.java

@@ -18,7 +18,7 @@ import org.briarproject.briar.api.blog.BlogManager;
 import org.briarproject.briar.api.blog.event.BlogInvitationRequestReceivedEvent;
 import org.briarproject.briar.api.blog.event.BlogInvitationResponseReceivedEvent;
 import org.briarproject.briar.api.client.MessageTracker;
-import org.briarproject.briar.api.sharing.InvitationRequest;
+import org.briarproject.briar.api.messaging.PrivateRequest;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
@@ -50,11 +50,10 @@ class BlogProtocolEngineImpl extends ProtocolEngineImpl<Blog> {
 	@Override
 	Event getInvitationRequestReceivedEvent(InviteMessage<Blog> m,
 			ContactId contactId, boolean available, boolean canBeOpened) {
-		InvitationRequest<Blog> request = invitationFactory
+		PrivateRequest<Blog> request = invitationFactory
 				.createInvitationRequest(false, false, true, false, m,
 						contactId, available, canBeOpened);
-		return new BlogInvitationRequestReceivedEvent(m.getShareable(),
-				contactId, request);
+		return new BlogInvitationRequestReceivedEvent(request, contactId);
 	}
 
 	@Override
@@ -62,9 +61,9 @@ class BlogProtocolEngineImpl extends ProtocolEngineImpl<Blog> {
 			ContactId contactId) {
 		BlogInvitationResponse response = invitationFactory
 				.createInvitationResponse(m.getId(), m.getContactGroupId(),
-						m.getTimestamp(), false, false, true, false,
-						m.getShareableId(), contactId, true);
-		return new BlogInvitationResponseReceivedEvent(contactId, response);
+						m.getTimestamp(), false, false, false, false,
+						true, m.getShareableId());
+		return new BlogInvitationResponseReceivedEvent(response, contactId);
 	}
 
 	@Override
@@ -72,9 +71,9 @@ class BlogProtocolEngineImpl extends ProtocolEngineImpl<Blog> {
 			ContactId contactId) {
 		BlogInvitationResponse response = invitationFactory
 				.createInvitationResponse(m.getId(), m.getContactGroupId(),
-						m.getTimestamp(), false, false, true, false,
-						m.getShareableId(), contactId, true);
-		return new BlogInvitationResponseReceivedEvent(contactId, response);
+						m.getTimestamp(), false, false, false, false,
+						false, m.getShareableId());
+		return new BlogInvitationResponseReceivedEvent(response, contactId);
 	}
 
 	@Override

briar-core/src/main/java/org/briarproject/briar/sharing/BlogSharingManagerImpl.java

@@ -80,8 +80,8 @@ class BlogSharingManagerImpl extends SharingManagerImpl<Blog>
 
 		// Pre-share both blogs, if they have not been shared already
 		try {
-			preShareShareable(txn, c, ourBlog);
-			preShareShareable(txn, c, theirBlog);
+			preShareGroup(txn, c, ourBlog.getGroup());
+			preShareGroup(txn, c, theirBlog.getGroup());
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}

briar-core/src/main/java/org/briarproject/briar/sharing/ForumInvitationFactoryImpl.java

@@ -24,17 +24,16 @@ public class ForumInvitationFactoryImpl
 		SessionId sessionId = new SessionId(m.getShareableId().getBytes());
 		return new ForumInvitationRequest(m.getId(), m.getContactGroupId(),
 				m.getTimestamp(), local, sent, seen, read, sessionId,
-				m.getShareable(), c, m.getMessage(), available, canBeOpened);
+				m.getShareable(), m.getMessage(), available, canBeOpened);
 	}
 
 	@Override
 	public ForumInvitationResponse createInvitationResponse(MessageId id,
 			GroupId contactGroupId, long time, boolean local, boolean sent,
-			boolean seen, boolean read, GroupId shareableId,
-			ContactId contactId, boolean accept) {
+			boolean seen, boolean read, boolean accept, GroupId shareableId) {
 		SessionId sessionId = new SessionId(shareableId.getBytes());
 		return new ForumInvitationResponse(id, contactGroupId, time, local,
-				sent, seen, read, sessionId, shareableId, contactId, accept);
+				sent, seen, read, sessionId, accept, shareableId);
 	}
 
 }

briar-core/src/main/java/org/briarproject/briar/sharing/ForumMessageParserImpl.java

@@ -24,7 +24,7 @@ class ForumMessageParserImpl extends MessageParserImpl<Forum> {
 	}
 
 	@Override
-	protected Forum createShareable(BdfList descriptor) throws FormatException {
+	public Forum createShareable(BdfList descriptor) throws FormatException {
 		// Name, salt
 		String name = descriptor.getString(0);
 		byte[] salt = descriptor.getRaw(1);

briar-core/src/main/java/org/briarproject/briar/sharing/ForumProtocolEngineImpl.java

@@ -18,7 +18,7 @@ import org.briarproject.briar.api.forum.ForumInvitationResponse;
 import org.briarproject.briar.api.forum.ForumManager;
 import org.briarproject.briar.api.forum.event.ForumInvitationRequestReceivedEvent;
 import org.briarproject.briar.api.forum.event.ForumInvitationResponseReceivedEvent;
-import org.briarproject.briar.api.sharing.InvitationRequest;
+import org.briarproject.briar.api.messaging.PrivateRequest;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
@@ -31,8 +31,7 @@ import static org.briarproject.briar.api.forum.ForumManager.MAJOR_VERSION;
 class ForumProtocolEngineImpl extends ProtocolEngineImpl<Forum> {
 
 	private final ForumManager forumManager;
-	private final InvitationFactory<Forum, ForumInvitationResponse>
-			invitationFactory;
+	private final InvitationFactory<Forum, ForumInvitationResponse> invitationFactory;
 
 	@Inject
 	ForumProtocolEngineImpl(DatabaseComponent db,
@@ -52,11 +51,10 @@ class ForumProtocolEngineImpl extends ProtocolEngineImpl<Forum> {
 	@Override
 	Event getInvitationRequestReceivedEvent(InviteMessage<Forum> m,
 			ContactId contactId, boolean available, boolean canBeOpened) {
-		InvitationRequest<Forum> request = invitationFactory
+		PrivateRequest<Forum> request = invitationFactory
 				.createInvitationRequest(false, false, true, false, m,
 						contactId, available, canBeOpened);
-		return new ForumInvitationRequestReceivedEvent(m.getShareable(),
-				contactId, request);
+		return new ForumInvitationRequestReceivedEvent(request, contactId);
 	}
 
 	@Override
@@ -65,8 +63,8 @@ class ForumProtocolEngineImpl extends ProtocolEngineImpl<Forum> {
 		ForumInvitationResponse response = invitationFactory
 				.createInvitationResponse(m.getId(), m.getContactGroupId(),
 						m.getTimestamp(), false, false, true, false,
-						m.getShareableId(), contactId, true);
-		return new ForumInvitationResponseReceivedEvent(contactId, response);
+						true, m.getShareableId());
+		return new ForumInvitationResponseReceivedEvent(response, contactId);
 	}
 
 	@Override
@@ -75,8 +73,8 @@ class ForumProtocolEngineImpl extends ProtocolEngineImpl<Forum> {
 		ForumInvitationResponse response = invitationFactory
 				.createInvitationResponse(m.getId(), m.getContactGroupId(),
 						m.getTimestamp(), false, false, true, false,
-						m.getShareableId(), contactId, true);
-		return new ForumInvitationResponseReceivedEvent(contactId, response);
+						false, m.getShareableId());
+		return new ForumInvitationResponseReceivedEvent(response, contactId);
 	}
 
 	@Override

briar-core/src/main/java/org/briarproject/briar/sharing/InvitationFactory.java

@@ -3,19 +3,18 @@ package org.briarproject.briar.sharing;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.api.sharing.InvitationRequest;
+import org.briarproject.briar.api.messaging.PrivateRequest;
 import org.briarproject.briar.api.sharing.InvitationResponse;
 import org.briarproject.briar.api.sharing.Shareable;
 
-public interface InvitationFactory<S extends Shareable, I extends InvitationResponse> {
+public interface InvitationFactory<S extends Shareable, R extends InvitationResponse> {
 
-	InvitationRequest<S> createInvitationRequest(boolean local, boolean sent,
+	PrivateRequest<S> createInvitationRequest(boolean local, boolean sent,
 			boolean seen, boolean read, InviteMessage<S> m, ContactId c,
 			boolean available, boolean canBeOpened);
 
-	I createInvitationResponse(MessageId id,
-			GroupId contactGroupId, long time, boolean local, boolean sent,
-			boolean seen, boolean read, GroupId shareableId,
-			ContactId contactId, boolean accept);
+	R createInvitationResponse(MessageId id, GroupId contactGroupId, long time,
+			boolean local, boolean sent, boolean seen, boolean read,
+			boolean accept, GroupId shareableId);
 
 }

briar-core/src/main/java/org/briarproject/briar/sharing/MessageParser.java

@@ -22,6 +22,8 @@ interface MessageParser<S extends Shareable> {
 
 	MessageMetadata parseMetadata(BdfDictionary meta) throws FormatException;
 
+	S createShareable(BdfList descriptor) throws FormatException;
+
 	InviteMessage<S> getInviteMessage(Transaction txn, MessageId m)
 			throws DbException, FormatException;
 

briar-core/src/main/java/org/briarproject/briar/sharing/MessageParserImpl.java

@@ -94,9 +94,6 @@ abstract class MessageParserImpl<S extends Shareable>
 				m.getGroupId(), shareable, message, m.getTimestamp());
 	}
 
-	protected abstract S createShareable(BdfList descriptor)
-			throws FormatException;
-
 	@Override
 	public AcceptMessage parseAcceptMessage(Message m, BdfList body)
 			throws FormatException {

briar-core/src/main/java/org/briarproject/briar/sharing/ProtocolEngineImpl.java

@@ -293,7 +293,7 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 		if (m.getTimestamp() <= s.getInviteTimestamp())
 			return abortWithMessage(txn, s);
 		// The dependency, if any, must be the last remote message
-		if (!isValidDependency(s, m.getPreviousMessageId()))
+		if (isInvalidDependency(s, m.getPreviousMessageId()))
 			return abortWithMessage(txn, s);
 		// Mark the invite message visible in the UI and (un)available to answer
 		markMessageVisibleInUi(txn, m.getId());
@@ -317,7 +317,7 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 		if (m.getTimestamp() <= s.getInviteTimestamp())
 			return abortWithMessage(txn, s);
 		// The dependency, if any, must be the last remote message
-		if (!isValidDependency(s, m.getPreviousMessageId()))
+		if (isInvalidDependency(s, m.getPreviousMessageId()))
 			return abortWithMessage(txn, s);
 		// Mark the invite message visible in the UI and unavailable to answer
 		markMessageVisibleInUi(txn, m.getId());
@@ -364,7 +364,7 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 		if (m.getTimestamp() <= s.getInviteTimestamp())
 			return abortWithMessage(txn, s);
 		// The dependency, if any, must be the last remote message
-		if (!isValidDependency(s, m.getPreviousMessageId()))
+		if (isInvalidDependency(s, m.getPreviousMessageId()))
 			return abortWithMessage(txn, s);
 		// Mark the response visible in the UI
 		markMessageVisibleInUi(txn, m.getId());
@@ -416,7 +416,7 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 		if (m.getTimestamp() <= s.getInviteTimestamp())
 			return abortWithMessage(txn, s);
 		// The dependency, if any, must be the last remote message
-		if (!isValidDependency(s, m.getPreviousMessageId()))
+		if (isInvalidDependency(s, m.getPreviousMessageId()))
 			return abortWithMessage(txn, s);
 		// Mark the response visible in the UI
 		markMessageVisibleInUi(txn, m.getId());
@@ -463,7 +463,7 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 	private Session onRemoteLeaveWhenInvited(Transaction txn, Session s,
 			LeaveMessage m) throws DbException, FormatException {
 		// The dependency, if any, must be the last remote message
-		if (!isValidDependency(s, m.getPreviousMessageId()))
+		if (isInvalidDependency(s, m.getPreviousMessageId()))
 			return abortWithMessage(txn, s);
 		// Mark any invite messages in the session unavailable to answer
 		markInvitesUnavailableToAnswer(txn, s);
@@ -476,7 +476,7 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 	private Session onRemoteLeaveWhenLocalLeft(Transaction txn, Session s,
 			LeaveMessage m) throws DbException, FormatException {
 		// The dependency, if any, must be the last remote message
-		if (!isValidDependency(s, m.getPreviousMessageId()))
+		if (isInvalidDependency(s, m.getPreviousMessageId()))
 			return abortWithMessage(txn, s);
 		// Move to the next state
 		return new Session(START, s.getContactGroupId(), s.getShareableId(),
@@ -487,7 +487,7 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 	private Session onRemoteLeaveWhenSharing(Transaction txn, Session s,
 			LeaveMessage m) throws DbException, FormatException {
 		// The dependency, if any, must be the last remote message
-		if (!isValidDependency(s, m.getPreviousMessageId()))
+		if (isInvalidDependency(s, m.getPreviousMessageId()))
 			return abortWithMessage(txn, s);
 		// Broadcast event informing that contact left
 		ContactId contactId = getContactId(txn, s.getContactGroupId());
@@ -623,11 +623,11 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 		return new ContactId(meta.getLong(GROUP_KEY_CONTACT_ID).intValue());
 	}
 
-	private boolean isValidDependency(Session session,
+	private boolean isInvalidDependency(Session session,
 			@Nullable MessageId dependency) {
 		MessageId expected = session.getLastRemoteMessageId();
-		if (dependency == null) return expected == null;
-		return expected != null && dependency.equals(expected);
+		if (dependency == null) return expected != null;
+		return expected == null || !dependency.equals(expected);
 	}
 
 	private long getLocalTimestamp(Session session) {

briar-core/src/main/java/org/briarproject/briar/sharing/SharingManagerImpl.java

@@ -26,8 +26,8 @@ import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVersioningHook;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
-import org.briarproject.briar.api.sharing.InvitationMessage;
-import org.briarproject.briar.api.sharing.InvitationRequest;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
+import org.briarproject.briar.api.messaging.PrivateRequest;
 import org.briarproject.briar.api.sharing.InvitationResponse;
 import org.briarproject.briar.api.sharing.Shareable;
 import org.briarproject.briar.api.sharing.SharingInvitationItem;
@@ -156,29 +156,29 @@ abstract class SharingManagerImpl<S extends Shareable>
 	}
 
 	/**
-	 * Adds the given Shareable and initializes a session between us
+	 * Adds the given Group and initializes a session between us
 	 * and the Contact c in state SHARING.
 	 * If a session already exists, this does nothing.
 	 */
-	void preShareShareable(Transaction txn, Contact c, S shareable)
+	void preShareGroup(Transaction txn, Contact c, Group g)
 			throws DbException, FormatException {
 		// Return if a session already exists with the contact
 		GroupId contactGroupId = getContactGroup(c).getId();
 		StoredSession existingSession = getSession(txn, contactGroupId,
-				getSessionId(shareable.getId()));
+				getSessionId(g.getId()));
 		if (existingSession != null) return;
 
-		// Add the shareable
-		db.addGroup(txn, shareable.getGroup());
+		// Add the shareable's group
+		db.addGroup(txn, g);
 
 		// Apply the client's visibility
 		Visibility client = clientVersioningManager.getClientVisibility(txn,
 				c.getId(), getShareableClientId(), getShareableMajorVersion());
-		db.setGroupVisibility(txn, c.getId(), shareable.getId(), client);
+		db.setGroupVisibility(txn, c.getId(), g.getId(), client);
 
 		// Initialize session in sharing state
-		Session session = new Session(SHARING, contactGroupId,
-				shareable.getId(), null, null, 0, 0);
+		Session session = new Session(SHARING, contactGroupId, g.getId(),
+				null, null, 0, 0);
 		MessageId storageId = createStorageId(txn, contactGroupId);
 		storeSession(txn, storageId, session);
 	}
@@ -321,17 +321,16 @@ abstract class SharingManagerImpl<S extends Shareable>
 	}
 
 	@Override
-	public Collection<InvitationMessage> getInvitationMessages(ContactId c)
-			throws DbException {
-		List<InvitationMessage> messages;
-		Transaction txn = db.startTransaction(true);
+	public Collection<PrivateMessageHeader> getMessageHeaders(Transaction txn,
+			ContactId c) throws DbException {
 		try {
 			Contact contact = db.getContact(txn, c);
 			GroupId contactGroupId = getContactGroup(contact).getId();
 			BdfDictionary query = messageParser.getMessagesVisibleInUiQuery();
 			Map<MessageId, BdfDictionary> results = clientHelper
 					.getMessageMetadataAsDictionary(txn, contactGroupId, query);
-			messages = new ArrayList<>(results.size());
+			Collection<PrivateMessageHeader> messages =
+					new ArrayList<>(results.size());
 			for (Entry<MessageId, BdfDictionary> e : results.entrySet()) {
 				MessageId m = e.getKey();
 				MessageMetadata meta =
@@ -339,28 +338,23 @@ abstract class SharingManagerImpl<S extends Shareable>
 				MessageStatus status = db.getMessageStatus(txn, c, m);
 				MessageType type = meta.getMessageType();
 				if (type == INVITE) {
-					messages.add(
-							parseInvitationRequest(txn, c, m, meta, status));
+					messages.add(parseInvitationRequest(txn, c, m,
+							meta, status));
 				} else if (type == ACCEPT) {
-					messages.add(
-							parseInvitationResponse(c, contactGroupId, m, meta,
-									status, true));
+					messages.add(parseInvitationResponse(contactGroupId, m,
+							meta, status, true));
 				} else if (type == DECLINE) {
-					messages.add(
-							parseInvitationResponse(c, contactGroupId, m, meta,
-									status, false));
+					messages.add(parseInvitationResponse(contactGroupId, m,
+							meta, status, false));
 				}
 			}
-			db.commitTransaction(txn);
+			return messages;
 		} catch (FormatException e) {
 			throw new DbException(e);
-		} finally {
-			db.endTransaction(txn);
 		}
-		return messages;
 	}
 
-	private InvitationRequest parseInvitationRequest(Transaction txn,
+	private PrivateRequest<S> parseInvitationRequest(Transaction txn,
 			ContactId c, MessageId m, MessageMetadata meta,
 			MessageStatus status) throws DbException, FormatException {
 		// Look up the invite message to get the details of the private group
@@ -374,14 +368,12 @@ abstract class SharingManagerImpl<S extends Shareable>
 						meta.isAvailableToAnswer(), canBeOpened);
 	}
 
-	private InvitationResponse parseInvitationResponse(ContactId c,
-			GroupId contactGroupId, MessageId m, MessageMetadata meta,
-			MessageStatus status, boolean accept)
-			throws DbException, FormatException {
+	private InvitationResponse parseInvitationResponse(GroupId contactGroupId,
+			MessageId m, MessageMetadata meta, MessageStatus status,
+			boolean accept) {
 		return invitationFactory.createInvitationResponse(m, contactGroupId,
 				meta.getTimestamp(), meta.isLocal(), status.isSent(),
-				status.isSeen(), meta.isRead(), meta.getShareableId(), c,
-				accept);
+				status.isSeen(), meta.isRead(), accept, meta.getShareableId());
 	}
 
 	@Override

briar-core/src/test/java/org/briarproject/briar/blog/BlogManagerIntegrationTest.java

@@ -1,6 +1,5 @@
 package org.briarproject.briar.blog;
 
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.sync.MessageId;
@@ -63,10 +62,7 @@ public class BlogManagerIntegrationTest
 		blog1 = blogFactory.createBlog(author1);
 
 		rssBlog = blogFactory.createFeedBlog(rssAuthor);
-		Transaction txn = db0.startTransaction(false);
-		blogManager0.addBlog(txn, rssBlog);
-		db0.commitTransaction(txn);
-		db0.endTransaction(txn);
+		withinTransaction(db0, txn -> blogManager0.addBlog(txn, rssBlog));
 	}
 
 	@Override

briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java

@@ -9,8 +9,8 @@ import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.data.BdfEntry;
 import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.Author;
@@ -25,13 +25,13 @@ import org.briarproject.bramble.test.TestDatabaseModule;
 import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.introduction.IntroductionManager;
-import org.briarproject.briar.api.introduction.IntroductionMessage;
 import org.briarproject.briar.api.introduction.IntroductionRequest;
 import org.briarproject.briar.api.introduction.IntroductionResponse;
 import org.briarproject.briar.api.introduction.event.IntroductionAbortedEvent;
 import org.briarproject.briar.api.introduction.event.IntroductionRequestReceivedEvent;
 import org.briarproject.briar.api.introduction.event.IntroductionResponseReceivedEvent;
 import org.briarproject.briar.api.introduction.event.IntroductionSucceededEvent;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.test.BriarIntegrationTest;
 import org.junit.Before;
 import org.junit.Test;
@@ -159,7 +159,7 @@ public class IntroductionIntegrationTest
 		eventWaiter.await(TIMEOUT, 1);
 		assertTrue(listener0.response1Received);
 		assertEquals(introducee2.getAuthor().getName(),
-				listener0.getResponse().getName());
+				listener0.getResponse().getIntroducedAuthor().getName());
 		assertGroupCount(messageTracker0, g1.getId(), 2, 1);
 
 		// sync second ACCEPT message
@@ -167,7 +167,7 @@ public class IntroductionIntegrationTest
 		eventWaiter.await(TIMEOUT, 1);
 		assertTrue(listener0.response2Received);
 		assertEquals(introducee1.getAuthor().getName(),
-				listener0.getResponse().getName());
+				listener0.getResponse().getIntroducedAuthor().getName());
 		assertGroupCount(messageTracker0, g2.getId(), 2, 1);
 
 		// sync forwarded ACCEPT messages to introducees
@@ -265,7 +265,7 @@ public class IntroductionIntegrationTest
 
 		// assert that the name on the decline event is correct
 		assertEquals(introducee2.getAuthor().getName(),
-				listener0.getResponse().getName());
+				listener0.getResponse().getIntroducedAuthor().getName());
 
 		// sync second response
 		sync2To0(1, true);
@@ -282,7 +282,7 @@ public class IntroductionIntegrationTest
 		// assert that the name on the decline event is correct
 		eventWaiter.await(TIMEOUT, 1);
 		assertEquals(introducee1.getAuthor().getName(),
-				listener2.getResponse().getName());
+				listener2.getResponse().getIntroducedAuthor().getName());
 
 		// note how the introducer does not forward the second response,
 		// because after the first decline the protocol finished
@@ -297,22 +297,23 @@ public class IntroductionIntegrationTest
 
 		Group g1 = introductionManager0.getContactGroup(introducee1);
 		Group g2 = introductionManager0.getContactGroup(introducee2);
-		assertEquals(2,
-				introductionManager0.getIntroductionMessages(contactId1From0)
-						.size());
+		Collection<PrivateMessageHeader> messages =
+				withinTransactionReturns(db0, txn -> introductionManager0
+						.getMessageHeaders(txn, contactId1From0));
+		assertEquals(2, messages.size());
 		assertGroupCount(messageTracker0, g1.getId(), 2, 1);
-		assertEquals(2,
-				introductionManager0.getIntroductionMessages(contactId2From0)
-						.size());
+		messages = withinTransactionReturns(db0,
+				txn -> introductionManager0.getMessageHeaders(txn, contactId2From0));
+		assertEquals(2, messages.size());
 		assertGroupCount(messageTracker0, g2.getId(), 2, 1);
-		assertEquals(2,
-				introductionManager1.getIntroductionMessages(contactId0From1)
-						.size());
+		messages = withinTransactionReturns(db1,
+				txn -> introductionManager1.getMessageHeaders(txn, contactId0From1));
+		assertEquals(2, messages.size());
 		assertGroupCount(messageTracker1, g1.getId(), 2, 1);
 		// introducee2 should also have the decline response of introducee1
-		assertEquals(3,
-				introductionManager2.getIntroductionMessages(contactId0From2)
-						.size());
+		messages = withinTransactionReturns(db2,
+				txn -> introductionManager2.getMessageHeaders(txn, contactId0From2));
+		assertEquals(3, messages.size());
 		assertGroupCount(messageTracker2, g2.getId(), 3, 2);
 
 		assertFalse(listener0.aborted);
@@ -355,25 +356,29 @@ public class IntroductionIntegrationTest
 		// assert that the name on the decline event is correct
 		eventWaiter.await(TIMEOUT, 1);
 		assertEquals(contact2From0.getAuthor().getName(),
-				listener1.getResponse().getName());
+				listener1.getResponse().getIntroducedAuthor().getName());
 
 		assertFalse(contactManager1
 				.contactExists(author2.getId(), author1.getId()));
 		assertFalse(contactManager2
 				.contactExists(author1.getId(), author2.getId()));
 
-		assertEquals(2,
-				introductionManager0.getIntroductionMessages(contactId1From0)
-						.size());
-		assertEquals(2,
-				introductionManager0.getIntroductionMessages(contactId2From0)
-						.size());
-		assertEquals(3,
-				introductionManager1.getIntroductionMessages(contactId0From1)
-						.size());
-		assertEquals(3,
-				introductionManager2.getIntroductionMessages(contactId0From2)
-						.size());
+		Collection<PrivateMessageHeader> messages =
+				withinTransactionReturns(db0, txn -> introductionManager0
+						.getMessageHeaders(txn, contactId1From0));
+		assertEquals(2, messages.size());
+		messages = withinTransactionReturns(db0,
+				txn -> introductionManager0
+						.getMessageHeaders(txn, contactId2From0));
+		assertEquals(2, messages.size());
+		messages = withinTransactionReturns(db1,
+				txn -> introductionManager1
+						.getMessageHeaders(txn, contactId0From1));
+		assertEquals(3, messages.size());
+		messages = withinTransactionReturns(db2,
+				txn -> introductionManager2
+						.getMessageHeaders(txn, contactId0From2));
+		assertEquals(3, messages.size());
 		assertFalse(listener0.aborted);
 		assertFalse(listener1.aborted);
 		assertFalse(listener2.aborted);
@@ -482,7 +487,7 @@ public class IntroductionIntegrationTest
 		// assert that the name on the decline event is correct
 		eventWaiter.await(TIMEOUT, 1);
 		assertEquals(introducee1.getAuthor().getName(),
-				listener2.getResponse().getName());
+				listener2.getResponse().getIntroducedAuthor().getName());
 
 		// assert that introducee2 is in correct state
 		introduceeSession = getIntroduceeSession(c2);
@@ -519,21 +524,21 @@ public class IntroductionIntegrationTest
 
 		Group g1 = introductionManager0.getContactGroup(introducee1);
 		Group g2 = introductionManager0.getContactGroup(introducee2);
-		assertEquals(2,
-				introductionManager0.getIntroductionMessages(contactId1From0)
-						.size());
+		assertEquals(2, withinTransactionReturns(db0,
+				txn -> introductionManager0.getMessageHeaders(txn, contactId1From0))
+				.size());
 		assertGroupCount(messageTracker0, g1.getId(), 2, 1);
-		assertEquals(2,
-				introductionManager0.getIntroductionMessages(contactId2From0)
-						.size());
+		assertEquals(2, withinTransactionReturns(db0,
+				txn -> introductionManager0.getMessageHeaders(txn, contactId2From0))
+				.size());
 		assertGroupCount(messageTracker0, g2.getId(), 2, 1);
-		assertEquals(3,
-				introductionManager1.getIntroductionMessages(contactId0From1)
-						.size());
+		assertEquals(3, withinTransactionReturns(db1,
+				txn -> introductionManager1.getMessageHeaders(txn, contactId0From1))
+				.size());
 		assertGroupCount(messageTracker1, g1.getId(), 3, 2);
-		assertEquals(3,
-				introductionManager2.getIntroductionMessages(contactId0From2)
-						.size());
+		assertEquals(3, withinTransactionReturns(db2,
+				txn -> introductionManager2.getMessageHeaders(txn, contactId0From2))
+				.size());
 		assertGroupCount(messageTracker2, g2.getId(), 3, 2);
 
 		assertFalse(listener0.aborted);
@@ -557,7 +562,8 @@ public class IntroductionIntegrationTest
 		assertFalse(listener1.requestReceived);
 
 		// make really sure we don't have that request
-		assertTrue(introductionManager1.getIntroductionMessages(contactId0From1)
+		assertTrue(withinTransactionReturns(db1,
+				txn -> introductionManager1.getMessageHeaders(txn, contactId0From1))
 				.isEmpty());
 
 		// The message was invalid, so no abort message was sent
@@ -606,12 +612,12 @@ public class IntroductionIntegrationTest
 		sync0To2(1, true);
 
 		// assert that introducees get notified about the existing contact
-		IntroductionRequest ir1 =
-				getIntroductionRequest(introductionManager1, contactId0From1);
-		assertTrue(ir1.contactExists());
-		IntroductionRequest ir2 =
-				getIntroductionRequest(introductionManager2, contactId0From2);
-		assertTrue(ir2.contactExists());
+		IntroductionRequest ir1 = getIntroductionRequest(db1,
+				introductionManager1, contactId0From1);
+		assertTrue(ir1.isContact());
+		IntroductionRequest ir2 = getIntroductionRequest(db2,
+				introductionManager2, contactId0From2);
+		assertTrue(ir2.isContact());
 
 		// sync ACCEPT messages back to introducer
 		sync1To0(1, true);
@@ -991,8 +997,7 @@ public class IntroductionIntegrationTest
 		AcceptMessage m = visitor.visit(message);
 
 		// replace original response with modified one
-		Transaction txn = db0.startTransaction(false);
-		try {
+		withinTransaction(db0, txn -> {
 			db0.removeMessage(txn, message.getMessageId());
 			Message msg = c0.getMessageEncoder()
 					.encodeAcceptMessage(m.getGroupId(), m.getTimestamp(),
@@ -1012,10 +1017,7 @@ public class IntroductionIntegrationTest
 					session.getValue(), msg.getId());
 			c0.getClientHelper().mergeMessageMetadata(txn, session.getKey(),
 					session.getValue());
-			db0.commitTransaction(txn);
-		} finally {
-			db0.endTransaction(txn);
-		}
+		});
 
 		// sync second response
 		sync2To0(1, true);
@@ -1100,30 +1102,31 @@ public class IntroductionIntegrationTest
 	}
 
 	private void assertDefaultUiMessages() throws DbException {
-		Collection<IntroductionMessage> messages =
-				introductionManager0.getIntroductionMessages(contactId1From0);
+		Collection<PrivateMessageHeader> messages =
+				withinTransactionReturns(db0, txn -> introductionManager0
+						.getMessageHeaders(txn, contactId1From0));
 		assertEquals(2, messages.size());
 		assertMessagesAreAcked(messages);
 
-		messages = introductionManager0.getIntroductionMessages(
-				contactId2From0);
+		messages = withinTransactionReturns(db0,
+				txn -> introductionManager0.getMessageHeaders(txn, contactId2From0));
 		assertEquals(2, messages.size());
 		assertMessagesAreAcked(messages);
 
-		messages = introductionManager1.getIntroductionMessages(
-				contactId0From1);
+		messages = withinTransactionReturns(db1,
+				txn -> introductionManager1.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, messages.size());
 		assertMessagesAreAcked(messages);
 
-		messages = introductionManager2.getIntroductionMessages(
-				contactId0From2);
+		messages = withinTransactionReturns(db2,
+				txn -> introductionManager2.getMessageHeaders(txn, contactId0From2));
 		assertEquals(2, messages.size());
 		assertMessagesAreAcked(messages);
 	}
 
 	private void assertMessagesAreAcked(
-			Collection<IntroductionMessage> messages) {
-		for (IntroductionMessage msg : messages) {
+			Collection<PrivateMessageHeader> messages) {
+		for (PrivateMessageHeader msg : messages) {
 			if (msg.isLocal()) assertTrue(msg.isSeen());
 		}
 	}
@@ -1150,7 +1153,7 @@ public class IntroductionIntegrationTest
 			assertTrue(
 					latestEvent instanceof IntroductionResponseReceivedEvent);
 			return ((IntroductionResponseReceivedEvent) latestEvent)
-					.getIntroductionResponse();
+					.getMessageHeader();
 		}
 	}
 
@@ -1178,7 +1181,7 @@ public class IntroductionIntegrationTest
 				IntroductionRequestReceivedEvent introEvent =
 						((IntroductionRequestReceivedEvent) e);
 				requestReceived = true;
-				IntroductionRequest ir = introEvent.getIntroductionRequest();
+				IntroductionRequest ir = introEvent.getMessageHeader();
 				ContactId contactId = introEvent.getContactId();
 				sessionId = ir.getSessionId();
 				long time = clock.currentTimeMillis();
@@ -1219,7 +1222,7 @@ public class IntroductionIntegrationTest
 			assertTrue(
 					latestEvent instanceof IntroductionRequestReceivedEvent);
 			return ((IntroductionRequestReceivedEvent) latestEvent)
-					.getIntroductionRequest();
+					.getMessageHeader();
 		}
 	}
 
@@ -1296,11 +1299,12 @@ public class IntroductionIntegrationTest
 		} else throw new AssertionError("Not implemented");
 	}
 
-	private IntroductionRequest getIntroductionRequest(
+	private IntroductionRequest getIntroductionRequest(DatabaseComponent db,
 			IntroductionManager manager, ContactId contactId)
 			throws DbException {
-		for (IntroductionMessage im : manager
-				.getIntroductionMessages(contactId)) {
+		Collection<PrivateMessageHeader> messages = withinTransactionReturns(db,
+				txn -> manager.getMessageHeaders(txn, contactId));
+		for (PrivateMessageHeader im : messages) {
 			if (im instanceof IntroductionRequest) {
 				return (IntroductionRequest) im;
 			}

briar-core/src/test/java/org/briarproject/briar/privategroup/PrivateGroupManagerIntegrationTest.java

@@ -2,7 +2,6 @@ package org.briarproject.briar.privategroup;
 
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.data.BdfList;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.TestDatabaseModule;
@@ -245,11 +244,8 @@ public class PrivateGroupManagerIntegrationTest
 				groupManager0.getPreviousMsgId(groupId0));
 
 		// share the group with 1
-		Transaction txn0 = db0.startTransaction(false);
-		db0.setGroupVisibility(txn0, contactId1From0, privateGroup0.getId(),
-				SHARED);
-		db0.commitTransaction(txn0);
-		db0.endTransaction(txn0);
+		withinTransaction(db0, txn -> db0.setGroupVisibility(txn,
+				contactId1From0, privateGroup0.getId(), SHARED));
 
 		// author1 joins privateGroup0 with wrong timestamp
 		joinTime = clock.currentTimeMillis();
@@ -266,11 +262,8 @@ public class PrivateGroupManagerIntegrationTest
 				groupManager1.getPreviousMsgId(groupId0));
 
 		// share the group with 0
-		Transaction txn1 = db1.startTransaction(false);
-		db1.setGroupVisibility(txn1, contactId0From1, privateGroup0.getId(),
-				SHARED);
-		db1.commitTransaction(txn1);
-		db1.endTransaction(txn1);
+		withinTransaction(db1, txn -> db1.setGroupVisibility(txn,
+				contactId0From1, privateGroup0.getId(), SHARED));
 
 		// sync join messages
 		sync0To1(1, false);
@@ -303,11 +296,8 @@ public class PrivateGroupManagerIntegrationTest
 				groupManager0.getPreviousMsgId(groupId0));
 
 		// share the group with 1
-		Transaction txn0 = db0.startTransaction(false);
-		db0.setGroupVisibility(txn0, contactId1From0, privateGroup0.getId(),
-				SHARED);
-		db0.commitTransaction(txn0);
-		db0.endTransaction(txn0);
+		withinTransaction(db0, txn -> db0.setGroupVisibility(txn,
+				contactId1From0, privateGroup0.getId(), SHARED));
 
 		// author1 joins privateGroup0 with wrong signature in join message
 		joinTime = clock.currentTimeMillis();
@@ -325,11 +315,8 @@ public class PrivateGroupManagerIntegrationTest
 				groupManager1.getPreviousMsgId(groupId0));
 
 		// share the group with 0
-		Transaction txn1 = db1.startTransaction(false);
-		db1.setGroupVisibility(txn1, contactId0From1, privateGroup0.getId(),
-				SHARED);
-		db1.commitTransaction(txn1);
-		db1.endTransaction(txn1);
+		withinTransaction(db1, txn -> db1.setGroupVisibility(txn,
+				contactId0From1, privateGroup0.getId(), SHARED));
 
 		// sync join messages
 		sync0To1(1, false);
@@ -404,11 +391,8 @@ public class PrivateGroupManagerIntegrationTest
 		addGroup();
 
 		// share the group with 2
-		Transaction txn0 = db0.startTransaction(false);
-		db0.setGroupVisibility(txn0, contactId2From0, privateGroup0.getId(),
-				SHARED);
-		db0.commitTransaction(txn0);
-		db0.endTransaction(txn0);
+		withinTransaction(db0, txn -> db0.setGroupVisibility(txn,
+				contactId2From0, privateGroup0.getId(), SHARED));
 
 		// author2 joins privateGroup0
 		long joinTime = clock.currentTimeMillis();
@@ -420,14 +404,12 @@ public class PrivateGroupManagerIntegrationTest
 		GroupMessage joinMsg2 = groupMessageFactory
 				.createJoinMessage(privateGroup0.getId(), joinTime, author2,
 						inviteTime, creatorSignature);
-		Transaction txn2 = db2.startTransaction(false);
-		groupManager2.addPrivateGroup(txn2, privateGroup0, joinMsg2, false);
-
-		// share the group with 0
-		db2.setGroupVisibility(txn2, contactId0From1, privateGroup0.getId(),
-				SHARED);
-		db2.commitTransaction(txn2);
-		db2.endTransaction(txn2);
+		withinTransaction(db2, txn -> {
+			groupManager2.addPrivateGroup(txn, privateGroup0, joinMsg2, false);
+			// share the group with 0
+			db2.setGroupVisibility(txn,
+					contactId0From2, privateGroup0.getId(), SHARED);
+		});
 
 		// sync join messages
 		sync2To0(1, true);
@@ -458,16 +440,10 @@ public class PrivateGroupManagerIntegrationTest
 		}
 
 		// reveal contact relationship
-		Transaction txn1 = db1.startTransaction(false);
-		groupManager1
-				.relationshipRevealed(txn1, groupId0, author2.getId(), false);
-		db1.commitTransaction(txn1);
-		db1.endTransaction(txn1);
-		txn2 = db2.startTransaction(false);
-		groupManager2
-				.relationshipRevealed(txn2, groupId0, author1.getId(), true);
-		db2.commitTransaction(txn2);
-		db2.endTransaction(txn2);
+		withinTransaction(db1, txn -> groupManager1.relationshipRevealed(txn,
+				groupId0, author2.getId(), false));
+		withinTransaction(db2, txn -> groupManager2.relationshipRevealed(txn,
+				groupId0, author1.getId(), true));
 
 		// assert that contact relationship is now revealed properly
 		members1 = groupManager1.getMembers(groupId0);
@@ -520,10 +496,8 @@ public class PrivateGroupManagerIntegrationTest
 		assertFalse(groupManager1.isDissolved(groupId0));
 
 		// creator dissolves group
-		Transaction txn1 = db1.startTransaction(false);
-		groupManager1.markGroupDissolved(txn1, groupId0);
-		db1.commitTransaction(txn1);
-		db1.endTransaction(txn1);
+		withinTransaction(db1,
+				txn -> groupManager1.markGroupDissolved(txn, groupId0));
 
 		// group is dissolved now
 		assertTrue(groupManager1.isDissolved(groupId0));
@@ -539,11 +513,8 @@ public class PrivateGroupManagerIntegrationTest
 				groupManager0.getPreviousMsgId(groupId0));
 
 		// share the group with 1
-		Transaction txn0 = db0.startTransaction(false);
-		db0.setGroupVisibility(txn0, contactId1From0, privateGroup0.getId(),
-				SHARED);
-		db0.commitTransaction(txn0);
-		db0.endTransaction(txn0);
+		withinTransaction(db0, txn -> db0.setGroupVisibility(txn,
+				contactId1From0, privateGroup0.getId(), SHARED));
 
 		// author1 joins privateGroup0
 		joinTime = clock.currentTimeMillis();
@@ -558,11 +529,8 @@ public class PrivateGroupManagerIntegrationTest
 		groupManager1.addPrivateGroup(privateGroup0, joinMsg1, false);
 
 		// share the group with 0
-		Transaction txn1 = db1.startTransaction(false);
-		db1.setGroupVisibility(txn1, contactId0From1, privateGroup0.getId(),
-				SHARED);
-		db1.commitTransaction(txn1);
-		db1.endTransaction(txn1);
+		withinTransaction(db1, txn -> db1.setGroupVisibility(txn,
+				contactId0From1, privateGroup0.getId(), SHARED));
 		assertEquals(joinMsg1.getMessage().getId(),
 				groupManager1.getPreviousMsgId(groupId0));
 

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/GroupInvitationIntegrationTest.java

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.test.TestDatabaseModule;
 import org.briarproject.briar.api.client.ProtocolStateException;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.privategroup.GroupMessage;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
 import org.briarproject.briar.api.privategroup.PrivateGroupManager;
@@ -11,8 +12,6 @@ import org.briarproject.briar.api.privategroup.invitation.GroupInvitationItem;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationRequest;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
-import org.briarproject.briar.api.sharing.InvitationMessage;
-import org.briarproject.briar.api.sharing.InvitationResponse;
 import org.briarproject.briar.test.BriarIntegrationTest;
 import org.briarproject.briar.test.BriarIntegrationTestComponent;
 import org.briarproject.briar.test.DaggerBriarIntegrationTestComponent;
@@ -92,19 +91,20 @@ public class GroupInvitationIntegrationTest
 		assertEquals(privateGroup0.getName(), item.getName());
 		assertFalse(item.isSubscribed());
 
-		Collection<InvitationMessage> messages =
-				groupInvitationManager1.getInvitationMessages(contactId0From1);
+		Collection<PrivateMessageHeader> messages =
+				withinTransactionReturns(db1, txn -> groupInvitationManager1
+						.getMessageHeaders(txn, contactId0From1));
 		assertEquals(1, messages.size());
 		GroupInvitationRequest request =
 				(GroupInvitationRequest) messages.iterator().next();
 		assertEquals(msg, request.getMessage());
-		assertEquals(author0, request.getShareable().getCreator());
+		assertEquals(author0, request.getNameable().getCreator());
 		assertEquals(timestamp, request.getTimestamp());
-		assertEquals(contactId0From1, request.getContactId());
-		assertEquals(privateGroup0.getName(), request.getShareable().getName());
+		assertEquals(privateGroup0.getName(), request.getNameable().getName());
 		assertFalse(request.isLocal());
 		assertFalse(request.isRead());
 		assertFalse(request.canBeOpened());
+		assertFalse(request.wasAnswered());
 	}
 
 	@Test
@@ -118,15 +118,16 @@ public class GroupInvitationIntegrationTest
 		groupInvitationManager1
 				.respondToInvitation(contactId0From1, privateGroup0, false);
 
-		Collection<InvitationMessage> messages =
-				groupInvitationManager1.getInvitationMessages(contactId0From1);
+		Collection<PrivateMessageHeader> messages =
+				withinTransactionReturns(db1, txn -> groupInvitationManager1
+						.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, messages.size());
 		boolean foundResponse = false;
-		for (InvitationMessage m : messages) {
+		for (PrivateMessageHeader m : messages) {
 			if (m instanceof GroupInvitationResponse) {
 				foundResponse = true;
-				InvitationResponse response = (GroupInvitationResponse) m;
-				assertEquals(contactId0From1, response.getContactId());
+				GroupInvitationResponse response = (GroupInvitationResponse) m;
+				assertEquals(privateGroup0.getId(), response.getShareableId());
 				assertTrue(response.isLocal());
 				assertFalse(response.wasAccepted());
 			}
@@ -135,15 +136,15 @@ public class GroupInvitationIntegrationTest
 
 		sync1To0(1, true);
 
-		messages =
-				groupInvitationManager0.getInvitationMessages(contactId1From0);
+		messages = withinTransactionReturns(db0, txn -> groupInvitationManager0
+				.getMessageHeaders(txn, contactId1From0));
 		assertEquals(2, messages.size());
 		foundResponse = false;
-		for (InvitationMessage m : messages) {
+		for (PrivateMessageHeader m : messages) {
 			if (m instanceof GroupInvitationResponse) {
 				foundResponse = true;
-				InvitationResponse response = (GroupInvitationResponse) m;
-				assertEquals(contactId0From1, response.getContactId());
+				GroupInvitationResponse response = (GroupInvitationResponse) m;
+				assertEquals(privateGroup0.getId(), response.getShareableId());
 				assertFalse(response.isLocal());
 				assertFalse(response.wasAccepted());
 			}
@@ -167,31 +168,37 @@ public class GroupInvitationIntegrationTest
 		groupInvitationManager1
 				.respondToInvitation(contactId0From1, privateGroup0, true);
 
-		Collection<InvitationMessage> messages =
-				groupInvitationManager1.getInvitationMessages(contactId0From1);
+		Collection<PrivateMessageHeader> messages =
+				withinTransactionReturns(db1, txn -> groupInvitationManager1
+						.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, messages.size());
 		boolean foundResponse = false;
-		for (InvitationMessage m : messages) {
+		for (PrivateMessageHeader m : messages) {
 			if (m instanceof GroupInvitationResponse) {
 				foundResponse = true;
-				InvitationResponse response = (GroupInvitationResponse) m;
+				GroupInvitationResponse response = (GroupInvitationResponse) m;
+				assertEquals(privateGroup0.getId(), response.getShareableId());
 				assertTrue(response.wasAccepted());
 			} else {
-				assertTrue(((GroupInvitationRequest) m).canBeOpened());
+				GroupInvitationRequest request = (GroupInvitationRequest) m;
+				assertEquals(privateGroup0, request.getNameable());
+				assertTrue(request.wasAnswered());
+				assertTrue(request.canBeOpened());
 			}
 		}
 		assertTrue(foundResponse);
 
 		sync1To0(1, true);
 
-		messages =
-				groupInvitationManager0.getInvitationMessages(contactId1From0);
+		messages = withinTransactionReturns(db1, txn -> groupInvitationManager0
+				.getMessageHeaders(txn, contactId1From0));
 		assertEquals(2, messages.size());
 		foundResponse = false;
-		for (InvitationMessage m : messages) {
+		for (PrivateMessageHeader m : messages) {
 			if (m instanceof GroupInvitationResponse) {
 				foundResponse = true;
-				InvitationResponse response = (GroupInvitationResponse) m;
+				GroupInvitationResponse response = (GroupInvitationResponse) m;
+				assertEquals(privateGroup0.getId(), response.getShareableId());
 				assertTrue(response.wasAccepted());
 			}
 		}
@@ -219,9 +226,9 @@ public class GroupInvitationIntegrationTest
 		// 1 has one unread message
 		Group g0 = groupInvitationManager1.getContactGroup(contact0From1);
 		assertGroupCount(messageTracker1, g0.getId(), 1, 1, timestamp);
-		InvitationMessage m =
-				groupInvitationManager1.getInvitationMessages(contactId0From1)
-						.iterator().next();
+		PrivateMessageHeader m = withinTransactionReturns(db1,
+				txn -> groupInvitationManager1.getMessageHeaders(txn, contactId0From1)
+						.iterator().next());
 
 		groupInvitationManager1
 				.respondToInvitation(contactId0From1, privateGroup0, true);

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/GroupInvitationManagerImplTest.java

@@ -24,13 +24,13 @@ import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.briarproject.bramble.test.TestUtils;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
 import org.briarproject.briar.api.privategroup.PrivateGroupFactory;
 import org.briarproject.briar.api.privategroup.PrivateGroupManager;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationItem;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationRequest;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
-import org.briarproject.briar.api.sharing.InvitationMessage;
 import org.jmock.AbstractExpectations;
 import org.jmock.Expectations;
 import org.jmock.lib.legacy.ClassImposteriser;
@@ -669,8 +669,6 @@ public class GroupInvitationManagerImplTest extends BrambleMockTestCase {
 						invite.getCreator(), invite.getSalt());
 
 		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
 			oneOf(db).getContact(txn, contactId);
 			will(returnValue(contact));
 			oneOf(contactGroupFactory).createContactGroup(CLIENT_ID,
@@ -696,23 +694,22 @@ public class GroupInvitationManagerImplTest extends BrambleMockTestCase {
 			oneOf(messageParser).parseMetadata(meta2);
 			will(returnValue(messageMetadata2));
 			oneOf(db).getMessageStatus(txn, contactId, messageId2);
-			// end transaction
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
-		Collection<InvitationMessage> messages =
-				groupInvitationManager.getInvitationMessages(contactId);
+		Collection<PrivateMessageHeader> messages =
+				groupInvitationManager.getMessageHeaders(txn, contactId);
 		assertEquals(2, messages.size());
-		for (InvitationMessage m : messages) {
+		for (PrivateMessageHeader m : messages) {
 			assertEquals(contactGroup.getId(), m.getGroupId());
-			assertEquals(contactId, m.getContactId());
 			if (m.getId().equals(message.getId())) {
 				assertTrue(m instanceof GroupInvitationRequest);
 				assertEquals(time1, m.getTimestamp());
+				assertEquals(pg, ((GroupInvitationRequest) m).getNameable());
 			} else if (m.getId().equals(messageId2)) {
 				assertTrue(m instanceof GroupInvitationResponse);
 				assertEquals(time2, m.getTimestamp());
+				assertEquals(pg.getId(),
+						((GroupInvitationResponse) m).getShareableId());
 			} else {
 				throw new AssertionError();
 			}

briar-core/src/test/java/org/briarproject/briar/sharing/BlogSharingIntegrationTest.java

@@ -18,7 +18,7 @@ import org.briarproject.briar.api.blog.BlogManager;
 import org.briarproject.briar.api.blog.BlogSharingManager;
 import org.briarproject.briar.api.blog.event.BlogInvitationRequestReceivedEvent;
 import org.briarproject.briar.api.blog.event.BlogInvitationResponseReceivedEvent;
-import org.briarproject.briar.api.sharing.InvitationMessage;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.test.BriarIntegrationTest;
 import org.briarproject.briar.test.BriarIntegrationTestComponent;
 import org.briarproject.briar.test.DaggerBriarIntegrationTestComponent;
@@ -27,9 +27,7 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
-import java.util.ArrayList;
 import java.util.Collection;
-import java.util.List;
 
 import static org.briarproject.briar.api.blog.BlogSharingManager.CLIENT_ID;
 import static org.briarproject.briar.api.blog.BlogSharingManager.MAJOR_VERSION;
@@ -147,32 +145,30 @@ public class BlogSharingIntegrationTest
 		assertTrue(blogManager1.getBlogs().contains(blog2));
 
 		// invitee has one invitation message from sharer
-		List<InvitationMessage> list = new ArrayList<>(
-				blogSharingManager1.getInvitationMessages(contactId0From1));
+		Collection<PrivateMessageHeader> list = withinTransactionReturns(db1,
+				txn -> blogSharingManager1.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, list.size());
 		// check other things are alright with the message
-		for (InvitationMessage m : list) {
+		for (PrivateMessageHeader m : list) {
 			if (m instanceof BlogInvitationRequest) {
-				BlogInvitationRequest invitation =
-						(BlogInvitationRequest) m;
-				assertFalse(invitation.isAvailable());
+				BlogInvitationRequest invitation = (BlogInvitationRequest) m;
+				assertEquals(blog2, invitation.getNameable());
+				assertTrue(invitation.wasAnswered());
 				assertEquals(blog2.getAuthor().getName(),
-						invitation.getBlogAuthorName());
-				assertFalse(invitation.getShareable().isRssFeed());
-				assertEquals(contactId1From0, invitation.getContactId());
+						invitation.getName());
+				assertFalse(invitation.getNameable().isRssFeed());
 				assertEquals("Hi!", invitation.getMessage());
 			} else {
-				BlogInvitationResponse response =
-						(BlogInvitationResponse) m;
-				assertEquals(contactId0From1, response.getContactId());
+				BlogInvitationResponse response = (BlogInvitationResponse) m;
+				assertEquals(blog2.getId(), response.getShareableId());
 				assertTrue(response.wasAccepted());
 				assertTrue(response.isLocal());
 			}
 		}
 		// sharer has own invitation message and response
-		assertEquals(2,
-				blogSharingManager0.getInvitationMessages(contactId1From0)
-						.size());
+		assertEquals(2, withinTransactionReturns(db0,
+				txn -> blogSharingManager0.getMessageHeaders(txn, contactId1From0))
+				.size());
 		// blog can not be shared again
 		assertFalse(blogSharingManager0.canBeShared(blog2.getId(),
 				contact1From0));
@@ -222,31 +218,30 @@ public class BlogSharingIntegrationTest
 		assertTrue(blogManager1.getBlogs().contains(rssBlog));
 
 		// invitee has one invitation message from sharer
-		List<InvitationMessage> list = new ArrayList<>(
-				blogSharingManager1.getInvitationMessages(contactId0From1));
+		Collection<PrivateMessageHeader> list = withinTransactionReturns(db1,
+				txn -> blogSharingManager1.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, list.size());
 		// check other things are alright with the message
-		for (InvitationMessage m : list) {
+		for (PrivateMessageHeader m : list) {
 			if (m instanceof BlogInvitationRequest) {
-				BlogInvitationRequest invitation =
-						(BlogInvitationRequest) m;
-				assertFalse(invitation.isAvailable());
+				BlogInvitationRequest invitation = (BlogInvitationRequest) m;
+				assertEquals(rssBlog, invitation.getNameable());
+				assertTrue(invitation.wasAnswered());
 				assertEquals(rssBlog.getAuthor().getName(),
-						invitation.getBlogAuthorName());
-				assertTrue(invitation.getShareable().isRssFeed());
-				assertEquals(contactId1From0, invitation.getContactId());
+						invitation.getName());
+				assertTrue(invitation.getNameable().isRssFeed());
 				assertEquals("Hi!", invitation.getMessage());
 			} else {
-				BlogInvitationResponse response =
-						(BlogInvitationResponse) m;
-				assertEquals(contactId0From1, response.getContactId());
+				BlogInvitationResponse response = (BlogInvitationResponse) m;
+				assertEquals(rssBlog.getId(), response.getShareableId());
 				assertTrue(response.wasAccepted());
 				assertTrue(response.isLocal());
 			}
 		}
 		// sharer has own invitation message and response
-		assertEquals(2, blogSharingManager0.getInvitationMessages(
-				contactId1From0).size());
+		assertEquals(2, withinTransactionReturns(db0,
+				txn -> blogSharingManager0.getMessageHeaders(txn, contactId1From0))
+				.size());
 		// blog can not be shared again
 		assertFalse(blogSharingManager0.canBeShared(rssBlog.getId(),
 				contact1From0));
@@ -285,31 +280,29 @@ public class BlogSharingIntegrationTest
 		assertEquals(0, blogSharingManager1.getInvitations().size());
 
 		// invitee has one invitation message from sharer and one response
-		List<InvitationMessage> list = new ArrayList<>(
-				blogSharingManager1.getInvitationMessages(contactId0From1));
+		Collection<PrivateMessageHeader> list = withinTransactionReturns(db1,
+				txn -> blogSharingManager1.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, list.size());
 		// check things are alright with the  message
-		for (InvitationMessage m : list) {
+		for (PrivateMessageHeader m : list) {
 			if (m instanceof BlogInvitationRequest) {
-				BlogInvitationRequest invitation =
-						(BlogInvitationRequest) m;
-				assertFalse(invitation.isAvailable());
+				BlogInvitationRequest invitation = (BlogInvitationRequest) m;
+				assertEquals(blog2, invitation.getNameable());
+				assertTrue(invitation.wasAnswered());
 				assertEquals(blog2.getAuthor().getName(),
-						invitation.getBlogAuthorName());
-				assertEquals(contactId1From0, invitation.getContactId());
+						invitation.getName());
 				assertEquals(null, invitation.getMessage());
 			} else {
-				BlogInvitationResponse response =
-						(BlogInvitationResponse) m;
-				assertEquals(contactId0From1, response.getContactId());
+				BlogInvitationResponse response = (BlogInvitationResponse) m;
+				assertEquals(blog2.getId(), response.getShareableId());
 				assertFalse(response.wasAccepted());
 				assertTrue(response.isLocal());
 			}
 		}
 		// sharer has own invitation message and response
-		assertEquals(2,
-				blogSharingManager0.getInvitationMessages(contactId1From0)
-						.size());
+		assertEquals(2, withinTransactionReturns(db0,
+				txn -> blogSharingManager0.getMessageHeaders(txn, contactId1From0))
+				.size());
 		// blog can be shared again
 		assertTrue(
 				blogSharingManager0.canBeShared(blog2.getId(), contact1From0));
@@ -394,8 +387,9 @@ public class BlogSharingIntegrationTest
 		assertTrue(contacts.contains(contact0From1));
 
 		// make sure 1 knows that they have blog2 already
-		Collection<InvitationMessage> messages =
-				blogSharingManager1.getInvitationMessages(contactId0From1);
+		Collection<PrivateMessageHeader> messages =
+				withinTransactionReturns(db1, txn -> blogSharingManager1
+						.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, messages.size());
 		assertEquals(blog2, blogManager1.getBlog(blog2.getId()));
 
@@ -565,7 +559,7 @@ public class BlogSharingIntegrationTest
 				BlogInvitationRequestReceivedEvent event =
 						(BlogInvitationRequestReceivedEvent) e;
 				eventWaiter.assertEquals(contactId1From0, event.getContactId());
-				Blog b = event.getShareable();
+				Blog b = event.getMessageHeader().getNameable();
 				try {
 					Contact c = contactManager0.getContact(contactId1From0);
 					blogSharingManager0.respondToInvitation(b, c, true);
@@ -601,7 +595,7 @@ public class BlogSharingIntegrationTest
 						(BlogInvitationRequestReceivedEvent) e;
 				requestReceived = true;
 				if (!answer) return;
-				Blog b = event.getShareable();
+				Blog b = event.getMessageHeader().getNameable();
 				try {
 					eventWaiter.assertEquals(1,
 							blogSharingManager1.getInvitations().size());
@@ -624,7 +618,7 @@ public class BlogSharingIntegrationTest
 		}
 	}
 
-	private void listenToEvents(boolean accept) throws DbException {
+	private void listenToEvents(boolean accept) {
 		listener0 = new SharerListener();
 		c0.getEventBus().addListener(listener0);
 		listener1 = new InviteeListener(accept);

briar-core/src/test/java/org/briarproject/briar/sharing/ForumSharingIntegrationTest.java

@@ -5,7 +5,6 @@ import net.jodah.concurrentunit.Waiter;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -22,7 +21,7 @@ import org.briarproject.briar.api.forum.ForumPostHeader;
 import org.briarproject.briar.api.forum.ForumSharingManager;
 import org.briarproject.briar.api.forum.event.ForumInvitationRequestReceivedEvent;
 import org.briarproject.briar.api.forum.event.ForumInvitationResponseReceivedEvent;
-import org.briarproject.briar.api.sharing.InvitationMessage;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.sharing.SharingInvitationItem;
 import org.briarproject.briar.test.BriarIntegrationTest;
 import org.briarproject.briar.test.BriarIntegrationTestComponent;
@@ -32,9 +31,7 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
-import java.util.ArrayList;
 import java.util.Collection;
-import java.util.List;
 
 import static junit.framework.Assert.assertNotNull;
 import static org.briarproject.bramble.util.StringUtils.getRandomString;
@@ -131,31 +128,28 @@ public class ForumSharingIntegrationTest
 		assertEquals(1, forumManager1.getForums().size());
 
 		// invitee has one invitation message from sharer
-		List<InvitationMessage> list = new ArrayList<>(
-				forumSharingManager1.getInvitationMessages(contactId0From1));
+		Collection<PrivateMessageHeader> list = withinTransactionReturns(db1,
+				txn -> forumSharingManager1.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, list.size());
 		// check other things are alright with the forum message
-		for (InvitationMessage m : list) {
+		for (PrivateMessageHeader m : list) {
 			if (m instanceof ForumInvitationRequest) {
-				ForumInvitationRequest invitation =
-						(ForumInvitationRequest) m;
-				assertFalse(invitation.isAvailable());
-				assertEquals(forum0.getName(), invitation.getForumName());
-				assertEquals(contactId1From0, invitation.getContactId());
+				ForumInvitationRequest invitation = (ForumInvitationRequest) m;
+				assertTrue(invitation.wasAnswered());
+				assertEquals(forum0.getName(), invitation.getName());
+				assertEquals(forum0, invitation.getNameable());
 				assertEquals("Hi!", invitation.getMessage());
 				assertTrue(invitation.canBeOpened());
 			} else {
-				ForumInvitationResponse response =
-						(ForumInvitationResponse) m;
-				assertEquals(contactId0From1, response.getContactId());
+				ForumInvitationResponse response = (ForumInvitationResponse) m;
+				assertEquals(forum0.getId(), response.getShareableId());
 				assertTrue(response.wasAccepted());
 				assertTrue(response.isLocal());
 			}
 		}
 		// sharer has own invitation message and response
-		assertEquals(2,
-				forumSharingManager0.getInvitationMessages(contactId1From0)
-						.size());
+		assertEquals(2, withinTransactionReturns(db0, txn ->
+				forumSharingManager0.getMessageHeaders(txn, contactId1From0)).size());
 		// forum can not be shared again
 		Contact c1 = contactManager0.getContact(contactId1From0);
 		assertFalse(forumSharingManager0.canBeShared(forum0.getId(), c1));
@@ -190,31 +184,28 @@ public class ForumSharingIntegrationTest
 		assertEquals(0, forumSharingManager1.getInvitations().size());
 
 		// invitee has one invitation message from sharer and one response
-		List<InvitationMessage> list = new ArrayList<>(
-				forumSharingManager1.getInvitationMessages(contactId0From1));
+		Collection<PrivateMessageHeader> list = withinTransactionReturns(db1,
+				txn -> forumSharingManager1.getMessageHeaders(txn, contactId0From1));
 		assertEquals(2, list.size());
 		// check things are alright with the forum message
-		for (InvitationMessage m : list) {
+		for (PrivateMessageHeader m : list) {
 			if (m instanceof ForumInvitationRequest) {
-				ForumInvitationRequest invitation =
-						(ForumInvitationRequest) m;
-				assertFalse(invitation.isAvailable());
-				assertEquals(forum0.getName(), invitation.getForumName());
-				assertEquals(contactId1From0, invitation.getContactId());
+				ForumInvitationRequest invitation = (ForumInvitationRequest) m;
+				assertEquals(forum0, invitation.getNameable());
+				assertTrue(invitation.wasAnswered());
+				assertEquals(forum0.getName(), invitation.getName());
 				assertEquals(null, invitation.getMessage());
 				assertFalse(invitation.canBeOpened());
 			} else {
-				ForumInvitationResponse response =
-						(ForumInvitationResponse) m;
-				assertEquals(contactId0From1, response.getContactId());
+				ForumInvitationResponse response = (ForumInvitationResponse) m;
+				assertEquals(forum0.getId(), response.getShareableId());
 				assertFalse(response.wasAccepted());
 				assertTrue(response.isLocal());
 			}
 		}
 		// sharer has own invitation message and response
-		assertEquals(2,
-				forumSharingManager0.getInvitationMessages(contactId1From0)
-						.size());
+		assertEquals(2, withinTransactionReturns(db0, txn ->
+				forumSharingManager0.getMessageHeaders(txn, contactId1From0)).size());
 		// forum can be shared again
 		Contact c1 = contactManager0.getContact(contactId1From0);
 		assertTrue(forumSharingManager0.canBeShared(forum0.getId(), c1));
@@ -455,10 +446,7 @@ public class ForumSharingIntegrationTest
 		listenToEvents(true);
 
 		// invitee adds the same forum
-		Transaction txn = db1.startTransaction(false);
-		forumManager1.addForum(txn, forum0);
-		db1.commitTransaction(txn);
-		db1.endTransaction(txn);
+		withinTransaction(db1, txn -> forumManager1.addForum(txn, forum0));
 
 		// send invitation
 		forumSharingManager0
@@ -490,10 +478,12 @@ public class ForumSharingIntegrationTest
 				.contains(contact0From1));
 
 		// and both have each other's invitations (and no response)
-		assertEquals(2, forumSharingManager0
-				.getInvitationMessages(contactId1From0).size());
-		assertEquals(2, forumSharingManager1
-				.getInvitationMessages(contactId0From1).size());
+		assertEquals(2, withinTransactionReturns(db0, txn ->
+				forumSharingManager0.getMessageHeaders(txn, contactId1From0))
+				.size());
+		assertEquals(2, withinTransactionReturns(db1, txn ->
+				forumSharingManager1.getMessageHeaders(txn, contactId0From1))
+				.size());
 
 		// there are no more open invitations
 		assertTrue(forumSharingManager0.getInvitations().isEmpty());
@@ -568,17 +558,14 @@ public class ForumSharingIntegrationTest
 	@Test
 	public void testTwoContactsShareSameForum() throws Exception {
 		// second sharer adds the same forum
-		Transaction txn = db2.startTransaction(false);
-		db2.addGroup(txn, forum0.getGroup());
-		db2.commitTransaction(txn);
-		db2.endTransaction(txn);
+		withinTransaction(db2, txn -> db2.addGroup(txn, forum0.getGroup()));
 
 		// add listeners
-		listener0 = new SharerListener();
+		listener0 = new SharerListener(true);
 		c0.getEventBus().addListener(listener0);
 		listener1 = new InviteeListener(true, false);
 		c1.getEventBus().addListener(listener1);
-		listener2 = new SharerListener();
+		listener2 = new SharerListener(true);
 		c2.getEventBus().addListener(listener2);
 
 		// send invitation
@@ -748,8 +735,9 @@ public class ForumSharingIntegrationTest
 
 		// get invitation MessageId for later
 		MessageId invitationId = null;
-		for (InvitationMessage m : forumSharingManager1
-				.getInvitationMessages(contactId0From1)) {
+		Collection<PrivateMessageHeader> list = withinTransactionReturns(db1,
+				txn -> forumSharingManager1.getMessageHeaders(txn, contactId0From1));
+		for (PrivateMessageHeader m : list) {
 			if (m instanceof ForumInvitationRequest) {
 				invitationId = m.getId();
 			}
@@ -802,13 +790,22 @@ public class ForumSharingIntegrationTest
 	@NotNullByDefault
 	private class SharerListener implements EventListener {
 
+		private final boolean accept;
 		private volatile boolean requestReceived = false;
 		private volatile boolean responseReceived = false;
 
+		private SharerListener(boolean accept) {
+			this.accept = accept;
+		}
+
 		@Override
 		public void eventOccurred(Event e) {
 			if (e instanceof ForumInvitationResponseReceivedEvent) {
+				ForumInvitationResponseReceivedEvent event =
+						(ForumInvitationResponseReceivedEvent) e;
 				responseReceived = true;
+				eventWaiter.assertEquals(accept,
+						event.getMessageHeader().wasAccepted());
 				eventWaiter.resume();
 			}
 			// this is only needed for tests where a forum is re-shared
@@ -817,7 +814,7 @@ public class ForumSharingIntegrationTest
 						(ForumInvitationRequestReceivedEvent) e;
 				eventWaiter.assertEquals(contactId1From0, event.getContactId());
 				requestReceived = true;
-				Forum f = event.getShareable();
+				Forum f = event.getMessageHeader().getNameable();
 				try {
 					if (respond) {
 						Contact c = contactManager0.getContact(contactId1From0);
@@ -855,7 +852,7 @@ public class ForumSharingIntegrationTest
 						(ForumInvitationRequestReceivedEvent) e;
 				requestReceived = true;
 				if (!answer) return;
-				Forum f = event.getShareable();
+				Forum f = event.getMessageHeader().getNameable();
 				try {
 					if (respond) {
 						eventWaiter.assertEquals(1,
@@ -880,17 +877,19 @@ public class ForumSharingIntegrationTest
 				ForumInvitationResponseReceivedEvent event =
 						(ForumInvitationResponseReceivedEvent) e;
 				eventWaiter.assertEquals(contactId0From1, event.getContactId());
+				eventWaiter.assertEquals(accept,
+						event.getMessageHeader().wasAccepted());
 				eventWaiter.resume();
 			}
 		}
 	}
 
-	private void listenToEvents(boolean accept) throws DbException {
-		listener0 = new SharerListener();
+	private void listenToEvents(boolean accept) {
+		listener0 = new SharerListener(accept);
 		c0.getEventBus().addListener(listener0);
 		listener1 = new InviteeListener(accept);
 		c1.getEventBus().addListener(listener1);
-		listener2 = new SharerListener();
+		listener2 = new SharerListener(accept);
 		c2.getEventBus().addListener(listener2);
 	}
 

briar-core/src/test/java/org/briarproject/briar/test/BriarIntegrationTest.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.test;
 
 import net.jodah.concurrentunit.Waiter;
 
+import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.client.ContactGroupFactory;
 import org.briarproject.bramble.api.contact.Contact;
@@ -10,6 +11,7 @@ import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.AuthorFactory;
@@ -376,4 +378,41 @@ public abstract class BriarIntegrationTest<C extends BriarIntegrationTestCompone
 		assertNotNull(contactId1From2);
 		contactManager2.removeContact(contactId1From2);
 	}
+
+	@FunctionalInterface
+	protected interface TransactionScope {
+		void execute(Transaction txn) throws DbException, FormatException;
+	}
+
+	protected void withinTransaction(DatabaseComponent db,
+			TransactionScope scope) throws DbException {
+		Transaction txn = db.startTransaction(false);
+		try {
+			scope.execute(txn);
+			db.commitTransaction(txn);
+		} catch (FormatException e) {
+			throw new DbException(e);
+		} finally {
+			db.endTransaction(txn);
+		}
+	}
+
+	@FunctionalInterface
+	protected interface TransactionResultScope<R> {
+		R execute(Transaction txn) throws DbException;
+	}
+
+	protected <R> R withinTransactionReturns(DatabaseComponent db,
+			TransactionResultScope<R> scope) throws DbException {
+		Transaction txn = db.startTransaction(false);
+		R r;
+		try {
+			r = scope.execute(txn);
+			db.commitTransaction(txn);
+		} finally {
+			db.endTransaction(txn);
+		}
+		return r;
+	}
+
 }