diff --git a/src/main/java/de/thm/arsnova/dao/CouchDBDao.java b/src/main/java/de/thm/arsnova/dao/CouchDBDao.java
new file mode 100644
index 0000000000000000000000000000000000000000..a799fc4f1874258b5c794ed6bd9590ac67f63e01
--- /dev/null
+++ b/src/main/java/de/thm/arsnova/dao/CouchDBDao.java
@@ -0,0 +1,376 @@
+/*
+ * Copyright (C) 2012 THM webMedia
+ * 
+ * This file is part of ARSnova.
+ *
+ * ARSnova is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.dao;
+
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import net.sf.json.JSONException;
+import net.sf.json.JSONObject;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.annotation.Isolation;
+import org.springframework.transaction.annotation.Transactional;
+
+import com.fourspaces.couchdb.Database;
+import com.fourspaces.couchdb.Document;
+import com.fourspaces.couchdb.View;
+import com.fourspaces.couchdb.ViewResults;
+
+import de.thm.arsnova.entities.Feedback;
+import de.thm.arsnova.entities.Session;
+import de.thm.arsnova.entities.User;
+import de.thm.arsnova.services.ISessionService;
+import de.thm.arsnova.services.IUserService;
+
+@Component
+public class CouchDBDao implements IDatabaseDao {
+	@Autowired
+	IUserService userService;
+	
+	@Autowired
+	ISessionService sessionService;
+	
+	private String databaseHost;
+	private int databasePort;
+	private String databaseName;
+	
+	private Database database;
+	
+	//
+	
+	public static final Logger logger = LoggerFactory.getLogger(CouchDBDao.class);
+
+	@Value("${couchdb.host}")
+	public final void setDatabaseHost(String databaseHost) {
+		logger.info(databaseHost);
+		this.databaseHost = databaseHost;
+	}
+	
+	@Value("${couchdb.port}")
+	public final void setDatabasePort(String databasePort) {
+		logger.info(databasePort);
+		this.databasePort = Integer.parseInt(databasePort);
+	}
+	
+	@Value("${couchdb.name}")
+	public final void setDatabaseName(String databaseName) {
+		logger.info(databaseName);
+		this.databaseName = databaseName;
+	}
+	
+	/**
+	 * This method cleans up old feedback votes at the scheduled interval.
+	 */
+	@Override
+	public void cleanFeedbackVotes(int cleanupFeedbackDelay) {
+		final long timelimitInMillis = 60000 * cleanupFeedbackDelay;
+		final long maxAllowedTimeInMillis = System.currentTimeMillis() - timelimitInMillis;
+		
+		Map<String, Set<String>> affectedUsers = new HashMap<String, Set<String>>();
+		Set<String> allAffectedSessions = new HashSet<String>();
+		
+		List<Document> results = findFeedbackForDeletion(maxAllowedTimeInMillis);
+		for (Document d : results) {
+			try {
+				// Read the required document data
+				Document feedback = this.getDatabase().getDocument(d.getId());
+				String arsInternalSessionId = feedback.getString("sessionId");
+				String user = feedback.getString("user");
+				
+				// Store user and session data for later. We need this to communicate the changes back to the users.
+				Set<String> affectedArsSessions = affectedUsers.get(user);
+				if (affectedArsSessions == null) {
+					affectedArsSessions = new HashSet<String>();
+				}
+				affectedArsSessions.add(getSessionKeyword(arsInternalSessionId));
+				affectedUsers.put(user, affectedArsSessions);
+				allAffectedSessions.addAll(affectedArsSessions);
+				
+				this.database.deleteDocument(feedback);
+				logger.debug("Cleaning up Feedback document " + d.getId());
+			} catch (IOException e) {
+				logger.error("Could not delete Feedback document " + d.getId());
+			} catch (JSONException e) {
+				logger.error("Could not delete Feedback document {}, error is: {} ", new Object[] {d.getId(), e});
+			}
+		}
+		if (!results.isEmpty()) {
+			sessionService.broadcastFeedbackChanges(affectedUsers, allAffectedSessions);
+		}
+	}
+	
+
+
+	private List<Document> findFeedbackForDeletion(final long maxAllowedTimeInMillis) {
+		View cleanupFeedbackView = new View("understanding/cleanup");
+		cleanupFeedbackView.setStartKey("null");
+		cleanupFeedbackView.setEndKey(String.valueOf(maxAllowedTimeInMillis));
+		ViewResults feedbackForCleanup = this.getDatabase().view(cleanupFeedbackView);
+		return feedbackForCleanup.getResults();
+	}
+	
+	
+
+	@Override
+	public Session getSession(String keyword) {
+		View view = new View("session/by_keyword");
+		view.setKey(URLEncoder.encode("\"" + keyword + "\""));
+		ViewResults results = this.getDatabase().view(view);
+
+		if (results.getJSONArray("rows").optJSONObject(0) == null)
+			return null;
+
+		Session result = (Session) JSONObject.toBean(
+				results.getJSONArray("rows").optJSONObject(0)
+						.optJSONObject("value"), Session.class);
+
+		if (result.isActive() || result.getCreator().equals(this.actualUserName())) {
+			sessionService.addUserToSessionMap(this.actualUserName(), keyword);
+			return result;
+		}
+		
+		return null;
+	}
+	
+	@Override
+	public Session saveSession(Session session) {
+		
+		Document sessionDocument = new Document();
+		sessionDocument.put("type","session");
+		sessionDocument.put("name", session.getName());
+		sessionDocument.put("shortName", session.getShortName());
+		sessionDocument.put("keyword", sessionService.generateKeyword());
+		sessionDocument.put("creator", this.actualUserName());
+		sessionDocument.put("active", true);
+		try {
+			database.saveDocument(sessionDocument);
+		} catch (IOException e) {
+			return null;
+		}
+		
+		return this.getSession(sessionDocument.getString("keyword"));
+	}
+
+	@Override
+	public Feedback getFeedback(String keyword) {
+		String sessionId = this.getSessionId(keyword);
+		if (sessionId == null)
+			return null;
+
+		logger.info("Time: {}", this.currentTimestamp());
+
+		View view = new View("understanding/by_session");
+		view.setGroup(true);
+		view.setStartKey(URLEncoder.encode("[\"" + sessionId + "\"]"));
+		view.setEndKey(URLEncoder.encode("[\"" + sessionId + "\",{}]"));
+		ViewResults results = this.getDatabase().view(view);
+
+		logger.info("Feedback: {}", results.getJSONArray("rows"));
+
+		int values[] = { 0, 0, 0, 0 };
+		List<Integer> result = new ArrayList<Integer>();
+		
+		try {
+			for (int i = 0; i <= 3; i++) {
+				String key = results.getJSONArray("rows").optJSONObject(i)
+						.optJSONArray("key").getString(1);
+				if (key.equals("Bitte schneller"))
+					values[0] = results.getJSONArray("rows").optJSONObject(i)
+							.getInt("value");
+				if (key.equals("Kann folgen"))
+					values[1] = results.getJSONArray("rows").optJSONObject(i)
+							.getInt("value");
+				if (key.equals("Zu schnell"))
+					values[2] = results.getJSONArray("rows").optJSONObject(i)
+							.getInt("value");
+				if (key.equals("Nicht mehr dabei"))
+					values[3] = results.getJSONArray("rows").optJSONObject(i)
+							.getInt("value");
+			}
+		} catch (Exception e) {
+			return new Feedback(
+					values[0],
+					values[1],
+					values[2],
+					values[3]
+			);
+		}
+
+		return new Feedback(
+				values[0],
+				values[1],
+				values[2],
+				values[3]
+		);
+	}
+
+	@Override
+	public boolean saveFeedback(String keyword, int value, de.thm.arsnova.entities.User user) {
+		String sessionId = this.getSessionId(keyword);
+		if (sessionId == null) return false;
+		if (!(value >= 0 && value <= 3)) return false;
+		
+		Document feedback = new Document();
+		List<Document> postedFeedback = findPreviousFeedback(sessionId, user);
+		
+		// Feedback can only be posted once. If there already is some feedback, we need to update it.
+		if (!postedFeedback.isEmpty()) {
+			for (Document f : postedFeedback) {
+				// Use the first found feedback and update value and timestamp
+				try {
+					feedback = this.getDatabase().getDocument(f.getId());
+					feedback.put("value", feedbackValueToString(value));
+					feedback.put("timestamp", System.currentTimeMillis());
+				} catch (IOException e) {
+					return false;
+				}
+				break;
+			}
+		} else {
+			feedback.put("type", "understanding");
+			feedback.put("user", user.getUsername());
+			feedback.put("sessionId", sessionId);
+			feedback.put("timestamp", System.currentTimeMillis());
+			feedback.put("value", feedbackValueToString(value));
+		}
+		
+		try {
+			this.getDatabase().saveDocument(feedback);
+		} catch (IOException e) {
+			return false;
+		}
+		
+		return true;
+	}
+	
+	private List<Document> findPreviousFeedback(String sessionId, de.thm.arsnova.entities.User user) {
+		View view = new View("understanding/by_user");
+		try {
+			view.setKey(URLEncoder.encode("[\"" + sessionId + "\", \"" + user.getUsername() + "\"]", "UTF-8"));
+		} catch(UnsupportedEncodingException e) {
+			return Collections.<Document>emptyList();
+		}
+		ViewResults results = this.getDatabase().view(view);
+		return results.getResults();
+	}
+	
+	private String feedbackValueToString(int value) {
+		switch (value) {
+			case 0:
+				return "Bitte schneller";
+			case 1:
+				return "Kann folgen";
+			case 2:
+				return "Zu schnell";
+			case 3:
+				return "Nicht mehr dabei";
+			default:
+				return null;
+		}
+	}
+
+	@Override
+	@Transactional(isolation=Isolation.READ_COMMITTED)
+	public boolean sessionKeyAvailable(String keyword) {
+		View view = new View("session/by_keyword");
+		ViewResults results = this.getDatabase().view(view);
+		
+		return ! results.containsKey(keyword);
+	}
+	
+	private String getSessionId(String keyword) {
+		View view = new View("session/by_keyword");
+		view.setKey(URLEncoder.encode("\"" + keyword + "\""));
+		ViewResults results = this.getDatabase().view(view);
+
+		if (results.getJSONArray("rows").optJSONObject(0) == null)
+			return null;
+
+		return results.getJSONArray("rows").optJSONObject(0)
+				.optJSONObject("value").getString("_id");
+	}
+	
+	private String getSessionKeyword(String internalSessionId) {
+		try {
+			View view = new View("session/by_id");
+			view.setKey(URLEncoder.encode("\"" + internalSessionId + "\"", "UTF-8"));
+			ViewResults results = this.getDatabase().view(view);
+			for (Document d : results.getResults()) {
+				Document arsSession = this.getDatabase().getDocument(d.getId());
+				return arsSession.get("keyword").toString();
+			}
+		} catch (UnsupportedEncodingException e) {
+			return null;
+		} catch (IOException e) {
+			return null;
+		}
+		return null;
+	}
+
+	private String currentTimestamp() {
+		return Long.toString(System.currentTimeMillis());
+	}
+	
+	private String actualUserName() {
+		Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+		User user = userService.getUser(authentication);
+		if(user == null) return null;
+		return user.getUsername();
+	}
+
+	private Database getDatabase() {
+		if (database == null) {
+			try {
+				com.fourspaces.couchdb.Session session = new com.fourspaces.couchdb.Session(
+						databaseHost,
+						databasePort
+					);
+					
+				database = session.getDatabase(databaseName);
+			} catch (Exception e) {
+				logger.error(
+					"Cannot connect to CouchDB database '"
+					+ databaseName
+					+"' on host '"
+					+ databaseHost
+					+ "' using port "
+					+ databasePort
+				);
+			}
+		}
+		
+		return database;
+	}
+}
diff --git a/src/main/java/de/thm/arsnova/dao/IDatabaseDao.java b/src/main/java/de/thm/arsnova/dao/IDatabaseDao.java
new file mode 100644
index 0000000000000000000000000000000000000000..4d41043b543089feeaac2ff8c2b65afadcec9352
--- /dev/null
+++ b/src/main/java/de/thm/arsnova/dao/IDatabaseDao.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2012 THM webMedia
+ * 
+ * This file is part of ARSnova.
+ *
+ * ARSnova is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * ARSnova is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package de.thm.arsnova.dao;
+
+import de.thm.arsnova.entities.Feedback;
+import de.thm.arsnova.entities.Session;
+import de.thm.arsnova.entities.User;
+
+public interface IDatabaseDao {
+	public void cleanFeedbackVotes(int cleanupFeedbackDelay);
+	public Session getSession(String keyword);
+	public Session saveSession(Session session);
+	public Feedback getFeedback(String keyword);
+	public boolean saveFeedback(String keyword, int value, User user);
+	public boolean sessionKeyAvailable(String keyword);
+}
\ No newline at end of file
diff --git a/src/main/java/de/thm/arsnova/services/ISessionService.java b/src/main/java/de/thm/arsnova/services/ISessionService.java
index 4e353c774f7749f6cd61993da44c66b7186d8ef5..cbcd5c85631fb76924f0e42837eb97bfee643a62 100644
--- a/src/main/java/de/thm/arsnova/services/ISessionService.java
+++ b/src/main/java/de/thm/arsnova/services/ISessionService.java
@@ -16,9 +16,12 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+
 package de.thm.arsnova.services;
 
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 import de.thm.arsnova.entities.Feedback;
 import de.thm.arsnova.entities.Session;
@@ -31,10 +34,11 @@ public interface ISessionService {
 	public Session getSession(String keyword);
 	public Session saveSession(Session session);
 	public Feedback getFeedback(String keyword);
-	public boolean postFeedback(String keyword, int value, User user);
+	public boolean saveFeedback(String keyword, int value, User user);
 	public boolean sessionKeyAvailable(String keyword);
 	public String generateKeyword();
 	public void addUserToSessionMap(String username, String keyword);
 	public boolean isUserInSession(User user, String keyword);
 	public List<String> getUsersInSession(String keyword);
+	public void broadcastFeedbackChanges(Map<String, Set<String>> affectedUsers, Set<String> allAffectedSessions);
 }
\ No newline at end of file
diff --git a/src/main/java/de/thm/arsnova/services/SessionService.java b/src/main/java/de/thm/arsnova/services/SessionService.java
index accb4cd24f7431f1b6c19e06270a38e431dc0fa6..b175592525fda6b39989e454f13ed648ae6aaf53 100644
--- a/src/main/java/de/thm/arsnova/services/SessionService.java
+++ b/src/main/java/de/thm/arsnova/services/SessionService.java
@@ -16,40 +16,24 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+
 package de.thm.arsnova.services;
 
-import java.io.IOException;
-import java.io.UnsupportedEncodingException;
-import java.net.URLEncoder;
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
-import net.sf.json.JSONException;
-import net.sf.json.JSONObject;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.scheduling.annotation.Scheduled;
-import org.springframework.security.core.Authentication;
-import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Isolation;
 import org.springframework.transaction.annotation.Transactional;
 
-import com.fourspaces.couchdb.Database;
-import com.fourspaces.couchdb.Document;
-import com.fourspaces.couchdb.View;
-import com.fourspaces.couchdb.ViewResults;
-
+import de.thm.arsnova.dao.IDatabaseDao;
 import de.thm.arsnova.entities.Feedback;
 import de.thm.arsnova.entities.Session;
 import de.thm.arsnova.entities.User;
@@ -58,9 +42,6 @@ import de.thm.arsnova.socket.ARSnovaSocketIOServer;
 @Service
 public class SessionService implements ISessionService {
 
-	@Autowired
-	IUserService userService;
-	
 	@Autowired
 	ARSnovaSocketIOServer server;
 	
@@ -70,269 +51,42 @@ public class SessionService implements ISessionService {
 	@Value("${feedback.cleanup}")
 	private int cleanupFeedbackDelay;
 	
-	private String databaseHost;
-	private int databasePort;
-	private String databaseName;
-	
-	private Database database;
-	
 	private static final ConcurrentHashMap<String, String> user2session = new ConcurrentHashMap<String, String>();
 	
-	public static final Logger logger = LoggerFactory.getLogger(SessionService.class);
-
-	@Value("${couchdb.host}")
-	public final void setDatabaseHost(String databaseHost) {
-		logger.info(databaseHost);
-		this.databaseHost = databaseHost;
-	}
-	
-	@Value("${couchdb.port}")
-	public final void setDatabasePort(String databasePort) {
-		logger.info(databasePort);
-		this.databasePort = Integer.parseInt(databasePort);
-	}
-	
-	@Value("${couchdb.name}")
-	public final void setDatabaseName(String databaseName) {
-		logger.info(databaseName);
-		this.databaseName = databaseName;
-	}
+	@Autowired
+	IDatabaseDao sessionDao;
 	
-	/**
-	 * This method cleans up old feedback votes at the scheduled interval.
-	 */
 	@Override
 	@Scheduled(fixedDelay=5000)
 	public void cleanFeedbackVotes() {
-		final long timelimitInMillis = 60000 * cleanupFeedbackDelay;
-		final long maxAllowedTimeInMillis = System.currentTimeMillis() - timelimitInMillis;
-		
-		Map<String, Set<String>> affectedUsers = new HashMap<String, Set<String>>();
-		Set<String> allAffectedSessions = new HashSet<String>();
-		
-		List<Document> results = findFeedbackForDeletion(maxAllowedTimeInMillis);
-		for (Document d : results) {
-			try {
-				// Read the required document data
-				Document feedback = this.getDatabase().getDocument(d.getId());
-				String arsInternalSessionId = feedback.getString("sessionId");
-				String user = feedback.getString("user");
-				
-				// Store user and session data for later. We need this to communicate the changes back to the users.
-				Set<String> affectedArsSessions = affectedUsers.get(user);
-				if (affectedArsSessions == null) {
-					affectedArsSessions = new HashSet<String>();
-				}
-				affectedArsSessions.add(getSessionKeyword(arsInternalSessionId));
-				affectedUsers.put(user, affectedArsSessions);
-				allAffectedSessions.addAll(affectedArsSessions);
-				
-				this.database.deleteDocument(feedback);
-				logger.debug("Cleaning up Feedback document " + d.getId());
-			} catch (IOException e) {
-				logger.error("Could not delete Feedback document " + d.getId());
-			} catch (JSONException e) {
-				logger.error("Could not delete Feedback document {}, error is: {} ", new Object[] {d.getId(), e});
-			}
-		}
-		if (!results.isEmpty()) {
-			broadcastFeedbackChanges(affectedUsers, allAffectedSessions);
-		}
-	}
-	
-	/**
-	 * 
-	 * @param affectedUsers The user whose feedback got deleted along with all affected session keywords
-	 * @param allAffectedSessions For convenience, this represents the union of all session keywords mentioned above.
-	 */
-	private void broadcastFeedbackChanges(Map<String, Set<String>> affectedUsers, Set<String> allAffectedSessions) {
-		for (Map.Entry<String, Set<String>> e : affectedUsers.entrySet()) {
-			// Is this user registered with a socket connection?
-			String connectedSocket = user2session.get(e.getKey());
-			if (connectedSocket != null) {
-				this.server.reportDeletedFeedback(e.getKey(), e.getValue());
-			}
-		}
-		this.server.reportUpdatedFeedbackForSessions(allAffectedSessions);
+		sessionDao.cleanFeedbackVotes(cleanupFeedbackDelay);		
 	}
 
-	private List<Document> findFeedbackForDeletion(final long maxAllowedTimeInMillis) {
-		View cleanupFeedbackView = new View("understanding/cleanup");
-		cleanupFeedbackView.setStartKey("null");
-		cleanupFeedbackView.setEndKey(String.valueOf(maxAllowedTimeInMillis));
-		ViewResults feedbackForCleanup = this.getDatabase().view(cleanupFeedbackView);
-		return feedbackForCleanup.getResults();
-	}
-	
-	
-
 	@Override
 	public Session getSession(String keyword) {
-		View view = new View("session/by_keyword");
-		view.setKey(URLEncoder.encode("\"" + keyword + "\""));
-		ViewResults results = this.getDatabase().view(view);
-
-		if (results.getJSONArray("rows").optJSONObject(0) == null)
-			return null;
-
-		Session result = (Session) JSONObject.toBean(
-				results.getJSONArray("rows").optJSONObject(0)
-						.optJSONObject("value"), Session.class);
-
-		if (result.isActive() || result.getCreator().equals(this.actualUserName())) {
-			this.addUserToSessionMap(this.actualUserName(), keyword);
-			return result;
-		}
-		
-		return null;
+		return sessionDao.getSession(keyword);
 	}
-	
+
 	@Override
 	public Session saveSession(Session session) {
-		
-		Document sessionDocument = new Document();
-		sessionDocument.put("type","session");
-		sessionDocument.put("name", session.getName());
-		sessionDocument.put("shortName", session.getShortName());
-		sessionDocument.put("keyword", this.generateKeyword());
-		sessionDocument.put("creator", this.actualUserName());
-		sessionDocument.put("active", true);
-		try {
-			database.saveDocument(sessionDocument);
-		} catch (IOException e) {
-			return null;
-		}
-		
-		return this.getSession(sessionDocument.getString("keyword"));
+		return sessionDao.saveSession(session);
 	}
 
 	@Override
 	public Feedback getFeedback(String keyword) {
-		String sessionId = this.getSessionId(keyword);
-		if (sessionId == null)
-			return null;
-
-		logger.info("Time: {}", this.currentTimestamp());
-
-		View view = new View("understanding/by_session");
-		view.setGroup(true);
-		view.setStartKey(URLEncoder.encode("[\"" + sessionId + "\"]"));
-		view.setEndKey(URLEncoder.encode("[\"" + sessionId + "\",{}]"));
-		ViewResults results = this.getDatabase().view(view);
-
-		logger.info("Feedback: {}", results.getJSONArray("rows"));
-
-		int values[] = { 0, 0, 0, 0 };
-		List<Integer> result = new ArrayList<Integer>();
-		
-		try {
-			for (int i = 0; i <= 3; i++) {
-				String key = results.getJSONArray("rows").optJSONObject(i)
-						.optJSONArray("key").getString(1);
-				if (key.equals("Bitte schneller"))
-					values[0] = results.getJSONArray("rows").optJSONObject(i)
-							.getInt("value");
-				if (key.equals("Kann folgen"))
-					values[1] = results.getJSONArray("rows").optJSONObject(i)
-							.getInt("value");
-				if (key.equals("Zu schnell"))
-					values[2] = results.getJSONArray("rows").optJSONObject(i)
-							.getInt("value");
-				if (key.equals("Nicht mehr dabei"))
-					values[3] = results.getJSONArray("rows").optJSONObject(i)
-							.getInt("value");
-			}
-		} catch (Exception e) {
-			return new Feedback(
-					values[0],
-					values[1],
-					values[2],
-					values[3]
-			);
-		}
-
-		return new Feedback(
-				values[0],
-				values[1],
-				values[2],
-				values[3]
-		);
+		return sessionDao.getFeedback(keyword);
 	}
 
 	@Override
-	public boolean postFeedback(String keyword, int value, de.thm.arsnova.entities.User user) {
-		String sessionId = this.getSessionId(keyword);
-		if (sessionId == null) return false;
-		if (!(value >= 0 && value <= 3)) return false;
-		
-		Document feedback = new Document();
-		List<Document> postedFeedback = findPreviousFeedback(sessionId, user);
-		
-		// Feedback can only be posted once. If there already is some feedback, we need to update it.
-		if (!postedFeedback.isEmpty()) {
-			for (Document f : postedFeedback) {
-				// Use the first found feedback and update value and timestamp
-				try {
-					feedback = this.getDatabase().getDocument(f.getId());
-					feedback.put("value", feedbackValueToString(value));
-					feedback.put("timestamp", System.currentTimeMillis());
-				} catch (IOException e) {
-					return false;
-				}
-				break;
-			}
-		} else {
-			feedback.put("type", "understanding");
-			feedback.put("user", user.getUsername());
-			feedback.put("sessionId", sessionId);
-			feedback.put("timestamp", System.currentTimeMillis());
-			feedback.put("value", feedbackValueToString(value));
-		}
-		
-		try {
-			this.getDatabase().saveDocument(feedback);
-		} catch (IOException e) {
-			return false;
-		}
-		
-		return true;
-	}
-	
-	private List<Document> findPreviousFeedback(String sessionId, de.thm.arsnova.entities.User user) {
-		View view = new View("understanding/by_user");
-		try {
-			view.setKey(URLEncoder.encode("[\"" + sessionId + "\", \"" + user.getUsername() + "\"]", "UTF-8"));
-		} catch(UnsupportedEncodingException e) {
-			return Collections.<Document>emptyList();
-		}
-		ViewResults results = this.getDatabase().view(view);
-		return results.getResults();
-	}
-	
-	private String feedbackValueToString(int value) {
-		switch (value) {
-			case 0:
-				return "Bitte schneller";
-			case 1:
-				return "Kann folgen";
-			case 2:
-				return "Zu schnell";
-			case 3:
-				return "Nicht mehr dabei";
-			default:
-				return "";
-		}
+	public boolean saveFeedback(String keyword, int value, User user) {
+		return sessionDao.saveFeedback(keyword, value, user);
 	}
 
 	@Override
-	@Transactional(isolation=Isolation.READ_COMMITTED)
 	public boolean sessionKeyAvailable(String keyword) {
-		View view = new View("session/by_keyword");
-		ViewResults results = this.getDatabase().view(view);
-		
-		return ! results.containsKey(keyword);
+		return sessionDao.sessionKeyAvailable(keyword);
 	}
-	
+
 	@Override
 	public boolean isUserInSession(de.thm.arsnova.entities.User user, String keyword) {
 		if (keyword == null) return false;
@@ -357,47 +111,23 @@ public class SessionService implements ISessionService {
 	public void addUserToSessionMap(String username, String keyword) {
 		user2session.put(username, keyword);	
 	}
-	
-	private String getSessionId(String keyword) {
-		View view = new View("session/by_keyword");
-		view.setKey(URLEncoder.encode("\"" + keyword + "\""));
-		ViewResults results = this.getDatabase().view(view);
-
-		if (results.getJSONArray("rows").optJSONObject(0) == null)
-			return null;
 
-		return results.getJSONArray("rows").optJSONObject(0)
-				.optJSONObject("value").getString("_id");
-	}
-	
-	private String getSessionKeyword(String internalSessionId) {
-		try {
-			View view = new View("session/by_id");
-			view.setKey(URLEncoder.encode("\"" + internalSessionId + "\"", "UTF-8"));
-			ViewResults results = this.getDatabase().view(view);
-			for (Document d : results.getResults()) {
-				Document arsSession = this.getDatabase().getDocument(d.getId());
-				return arsSession.get("keyword").toString();
+	/**
+	 * 
+	 * @param affectedUsers The user whose feedback got deleted along with all affected session keywords
+	 * @param allAffectedSessions For convenience, this represents the union of all session keywords mentioned above.
+	 */
+	public void broadcastFeedbackChanges(Map<String, Set<String>> affectedUsers, Set<String> allAffectedSessions) {
+		for (Map.Entry<String, Set<String>> e : affectedUsers.entrySet()) {
+			// Is this user registered with a socket connection?
+			String connectedSocket = user2session.get(e.getKey());
+			if (connectedSocket != null) {
+				this.server.reportDeletedFeedback(e.getKey(), e.getValue());
 			}
-		} catch (UnsupportedEncodingException e) {
-			return "";
-		} catch (IOException e) {
-			return "";
 		}
-		return "";
-	}
-
-	private String currentTimestamp() {
-		return Long.toString(System.currentTimeMillis());
+		this.server.reportUpdatedFeedbackForSessions(allAffectedSessions);
 	}
 	
-	private String actualUserName() {
-		Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
-		User user = userService.getUser(authentication);
-		if(user == null) return null;
-		return user.getUsername();
-	}
-
 	@Override
 	public String generateKeyword() {
 		final int low = 10000000;
@@ -407,28 +137,4 @@ public class SessionService implements ISessionService {
 		if (this.sessionKeyAvailable(keyword)) return keyword;
 		return generateKeyword();
 	}
-	
-	private Database getDatabase() {
-		if (database == null) {
-			try {
-				com.fourspaces.couchdb.Session session = new com.fourspaces.couchdb.Session(
-						databaseHost,
-						databasePort
-					);
-					
-				database = session.getDatabase(databaseName);
-			} catch (Exception e) {
-				logger.error(
-					"Cannot connect to CouchDB database '"
-					+ databaseName
-					+"' on host '"
-					+ databaseHost
-					+ "' using port "
-					+ databasePort
-				);
-			}
-		}
-		
-		return database;
-	}
 }
diff --git a/src/main/java/de/thm/arsnova/socket/ARSnovaSocketIOServer.java b/src/main/java/de/thm/arsnova/socket/ARSnovaSocketIOServer.java
index 4fd8b001d82eca6a92bdf0b5c5b620b48b4ddcc0..87a61eb5007b2cb30afa23524962670afb1b3b1f 100644
--- a/src/main/java/de/thm/arsnova/socket/ARSnovaSocketIOServer.java
+++ b/src/main/java/de/thm/arsnova/socket/ARSnovaSocketIOServer.java
@@ -80,7 +80,7 @@ public class ARSnovaSocketIOServer {
 						if(u == null || sessionService.isUserInSession(u, data.getSessionkey()) == false) {
 							return;
 						}
-						sessionService.postFeedback(data.getSessionkey(), data.getValue(), u);
+						sessionService.saveFeedback(data.getSessionkey(), data.getValue(), u);
 						
 						/**
 						 * collect a list of users which are in the current session