diff --git a/pom.xml b/pom.xml
index 046ec55..244170b 100755
--- a/pom.xml
+++ b/pom.xml
@@ -28,7 +28,7 @@
 		<dependency>
 			<groupId>com.github.informatik-ag-ngl</groupId>
 			<artifactId>envoy-common</artifactId>
-			<version>develop-SNAPSHOT</version>
+			<version>f~groups-SNAPSHOT</version>
 		</dependency>
 		<dependency>
 			<groupId>com.github.informatik-ag-ngl</groupId>
diff --git a/src/main/java/envoy/server/data/Contact.java b/src/main/java/envoy/server/data/Contact.java
index 9f1320a..d1737d8 100644
--- a/src/main/java/envoy/server/data/Contact.java
+++ b/src/main/java/envoy/server/data/Contact.java
@@ -1,62 +1,77 @@
-package envoy.server.data;
-
-import javax.persistence.GeneratedValue;
-import javax.persistence.GenerationType;
-import javax.persistence.Id;
-import javax.persistence.MappedSuperclass;
-
-/**
- * This class acts as a superclass for all contacts, being {@link User}s and
- * {@link Group}s. <br>
- * <br>
- * Project: <strong>envoy-server-standalone</strong><br>
- * File: <strong>Contact.java</strong><br>
- * Created: <strong>24.03.2020</strong><br>
- * 
- * @author Maximilian K&auml;fer
- * @since Envoy Server Standalone v0.1-alpha
- */
-
-@MappedSuperclass
-// TODO add queries
-public abstract class Contact {
-
-	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY)
-	protected long		id;
-	protected String	name;
-
-	/**
-	 * @return a envoy.data.Contact object of this envoy.server.data.Contact object.
-	 * @since Envoy Server Standalone v0.1-beta
-	 */
-	public abstract envoy.data.Contact toCommon();
-
-	/**
-	 * @return the ID of this contact.
-	 * @since Envoy Server Standalone v0.1-beta
-	 */
-	public long getID() { return id; }
-
-	/**
-	 * Sets the ID of this contact.
-	 * 
-	 * @param id to set for this contact
-	 * @since Envoy Server Standalone v0.1-beta
-	 */
-	public void setID(long id) { this.id = id; }
-
-	/**
-	 * @return the name of this contact.
-	 * @since Envoy Server Standalone v0.1-beta
-	 */
-	public String getName() { return name; }
-
-	/**
-	 * Sets the name of this contact.
-	 * 
-	 * @param name to set for this contact
-	 * @since Envoy Server Standalone v0.1-beta
-	 */
-	public void setName(String name) { this.name = name; }
-}
+package envoy.server.data;
+
+import java.util.Set;
+
+import javax.persistence.*;
+
+/**
+ * This class acts as a superclass for all contacts, being {@link User}s and
+ * {@link Group}s. <br>
+ * <br>
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>Contact.java</strong><br>
+ * Created: <strong>24.03.2020</strong><br>
+ *
+ * @author Maximilian K&auml;fer
+ * @since Envoy Server Standalone v0.1-alpha
+ */
+
+@MappedSuperclass
+// TODO add queries
+public abstract class Contact {
+
+	@Id
+	@GeneratedValue(strategy = GenerationType.IDENTITY)
+	protected long		id;
+	protected String	name;
+
+	@ManyToMany(targetEntity = Contact.class, cascade = CascadeType.ALL)
+	protected Set<Contact> contacts;
+
+	/**
+	 * @return a {@link envoy.data.Contact} object of this envoy.server.data.Contact
+	 *         object.
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public abstract envoy.data.Contact toCommon();
+
+	/**
+	 * @return the ID of this contact.
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public long getID() { return id; }
+
+	/**
+	 * Sets the ID of this contact.
+	 *
+	 * @param id to set for this contact
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public void setID(long id) { this.id = id; }
+
+	/**
+	 * @return the name of this contact.
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public String getName() { return name; }
+
+	/**
+	 * Sets the name of this contact.
+	 *
+	 * @param name to set for this contact
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public void setName(String name) { this.name = name; }
+
+	/**
+	 * @return the contacts
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public Set<Contact> getContacts() { return contacts; }
+
+	/**
+	 * @param contacts the contacts to set
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public void setContacts(Set<Contact> contacts) { this.contacts = contacts; }
+}
diff --git a/src/main/java/envoy/server/data/Group.java b/src/main/java/envoy/server/data/Group.java
index 592475f..6c76df9 100644
--- a/src/main/java/envoy/server/data/Group.java
+++ b/src/main/java/envoy/server/data/Group.java
@@ -1,54 +1,34 @@
-package envoy.server.data;
-
-import java.util.List;
-import java.util.stream.Collectors;
-
-import javax.persistence.CascadeType;
-import javax.persistence.Entity;
-import javax.persistence.ManyToMany;
-import javax.persistence.NamedQueries;
-import javax.persistence.NamedQuery;
-import javax.persistence.Table;
-
-/**
- * This class serves as a way to let Hibernate communicate with the server
- * without bringing the dependency of JPA/Hibernate into the client.<br>
- * It will be referenced as "database group" to clarify between the different
- * group objects.<br>
- * <br>
- * Project: <strong>envoy-server-standalone</strong><br>
- * File: <strong>Group.java</strong><br>
- * Created: <strong>24.03.2020</strong><br>
- * 
- * @author Maximilian K&auml;fer
- * @since Envoy Server Standalone v0.1-alpha
- */
-@Entity
-@Table(name = "groups")
-@NamedQueries({ @NamedQuery(query = "SELECT g FROM Group g WHERE g.name = :name", name = "getGroupByName") })
-public class Group extends Contact {
-
-	@ManyToMany(targetEntity = Group.class, cascade = CascadeType.ALL)
-	private List<User> members;
-
-	/**
-	 * {@inheritDoc}
-	 */
-	@Override
-	public envoy.data.Group toCommon() { return new envoy.data.Group(id, name, members.stream().map(User::getID).collect(Collectors.toList())); }
-
-	/**
-	 * @return a list of all users that are a member of this group.
-	 * @since Envoy Server Standalone v0.1-beta
-	 */
-	public List<User> getMembers() { return members; }
-
-	/**
-	 * Sets the members of this group.
-	 * 
-	 * @param members a list of all users, that should be assigned to this group.
-	 * @since Envoy Server Standalone v0.1-beta
-	 */
-	public void setMembers(List<User> members) { this.members = members; }
-
-}
+package envoy.server.data;
+
+import java.util.stream.Collectors;
+
+import javax.persistence.*;
+
+import envoy.data.User;
+
+/**
+ * This class serves as a way to let Hibernate communicate with the server
+ * without bringing the dependency of JPA/Hibernate into the client.<br>
+ * It will be referenced as "database group" to clarify between the different
+ * group objects.<br>
+ * <br>
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>Group.java</strong><br>
+ * Created: <strong>24.03.2020</strong><br>
+ *
+ * @author Maximilian K&auml;fer
+ * @since Envoy Server Standalone v0.1-alpha
+ */
+@Entity
+@Table(name = "groups")
+@NamedQueries({ @NamedQuery(query = "SELECT g FROM Group g WHERE g.name = :name", name = "getGroupByName") })
+public class Group extends Contact {
+
+	/**
+	 * {@inheritDoc}
+	 */
+	@Override
+	public envoy.data.Group toCommon() {
+		return new envoy.data.Group(id, name, contacts.parallelStream().map(Contact::toCommon).map(User.class::cast).collect(Collectors.toSet()));
+	}
+}
diff --git a/src/main/java/envoy/server/data/PersistenceManager.java b/src/main/java/envoy/server/data/PersistenceManager.java
index 669cf7e..1dd82a8 100755
--- a/src/main/java/envoy/server/data/PersistenceManager.java
+++ b/src/main/java/envoy/server/data/PersistenceManager.java
@@ -124,7 +124,7 @@ public class PersistenceManager {
 
 	/**
 	 * Searches for a {@link Group} with a specific ID.
-	 * 
+	 *
 	 * @param id the id to search for
 	 * @return the group with the specific id
 	 * @since Envoy Server Standalone v0.1-beta
@@ -133,7 +133,7 @@ public class PersistenceManager {
 
 	/**
 	 * Searches for a {@link Contact} with a specific ID.
-	 * 
+	 *
 	 * @param id the id to search for
 	 * @return the contact with the specific id
 	 * @since Envoy Server Standalone v0.1-beta
@@ -227,8 +227,8 @@ public class PersistenceManager {
 	public void addUserContact(long userId1, long userId2) {
 
 		// Get users by ID
-		User	u1	= getUserById(userId1);
-		User	u2	= getUserById(userId2);
+		Contact	u1	= getContactById(userId1);
+		Contact	u2	= getContactById(userId2);
 
 		// Add users to each others contact lists
 		u1.getContacts().add(u2);
diff --git a/src/main/java/envoy/server/data/User.java b/src/main/java/envoy/server/data/User.java
index 2913a54..2f788f0 100755
--- a/src/main/java/envoy/server/data/User.java
+++ b/src/main/java/envoy/server/data/User.java
@@ -1,7 +1,7 @@
 package envoy.server.data;
 
 import java.util.Date;
-import java.util.List;
+import java.util.stream.Collectors;
 
 import javax.persistence.*;
 
@@ -38,14 +38,13 @@ public class User extends Contact {
 	private Date						lastSeen;
 	private envoy.data.User.UserStatus	status;
 
-	@ManyToMany(targetEntity = User.class, cascade = CascadeType.ALL)
-	private List<User> contacts;
-
 	/**
 	 * {@inheritDoc}
 	 */
 	@Override
-	public envoy.data.User toCommon() { return new envoy.data.User(id, name, status); }
+	public envoy.data.User toCommon() {
+		return new envoy.data.User(id, name, status, contacts.stream().map(Contact::toCommon).collect(Collectors.toSet()));
+	}
 
 	/**
 	 * @return the passwordHash of a {link envoy.data.User}
@@ -85,18 +84,4 @@ public class User extends Contact {
 	 * @see User#getStatus()
 	 */
 	public void setStatus(envoy.data.User.UserStatus status) { this.status = status; }
-
-	/**
-	 * @return the contacts of a {link envoy.data.User}
-	 * @since Envoy Server Standalone v0.1-alpha
-	 */
-	public List<User> getContacts() { return contacts; }
-
-	/**
-	 * @param contacts the contacts to set
-	 * @since Envoy Server Standalone v0.1-alpha
-	 * @see User#getContacts()
-	 */
-	public void setContacts(List<User> contacts) { this.contacts = contacts; }
-
 }
diff --git a/src/main/java/envoy/server/net/ConnectionManager.java b/src/main/java/envoy/server/net/ConnectionManager.java
index 9314b5c..883f510 100755
--- a/src/main/java/envoy/server/net/ConnectionManager.java
+++ b/src/main/java/envoy/server/net/ConnectionManager.java
@@ -8,7 +8,6 @@ import com.jenkov.nioserver.ISocketIdListener;
 import envoy.data.User.UserStatus;
 import envoy.server.data.Group;
 import envoy.server.data.PersistenceManager;
-import envoy.server.data.User;
 import envoy.server.processors.UserStatusChangeProcessor;
 
 /**
@@ -113,7 +112,7 @@ public class ConnectionManager implements ISocketIdListener {
 	 */
 	public Set<Long> getOnlineUsersOfGroup(Group group) {
 		Set<Long>	onlineMembers	= new HashSet<>();
-		Set<Long>	members			= group.getMembers().stream().map(User::getID).collect(Collectors.toSet());
+		Set<Long>	members			= group.getContacts().stream().map(envoy.server.data.Contact::getID).collect(Collectors.toSet());
 		members.forEach(userID -> { if (isOnline(userID)) onlineMembers.add(userID); });
 		return onlineMembers;
 	}
diff --git a/src/main/java/envoy/server/processors/ContactOperationProcessor.java b/src/main/java/envoy/server/processors/ContactOperationProcessor.java
index f9f9133..fa67c55 100755
--- a/src/main/java/envoy/server/processors/ContactOperationProcessor.java
+++ b/src/main/java/envoy/server/processors/ContactOperationProcessor.java
@@ -3,8 +3,7 @@ package envoy.server.processors;
 import java.io.IOException;
 import java.util.Arrays;
 
-import envoy.data.Contacts;
-import envoy.event.ContactOperationEvent;
+import envoy.event.contact.ContactOperationEvent;
 import envoy.server.data.PersistenceManager;
 import envoy.server.net.ConnectionManager;
 import envoy.server.net.ObjectWriteProxy;
@@ -33,7 +32,7 @@ public class ContactOperationProcessor implements ObjectProcessor<ContactOperati
 
 				// Notify the contact if online
 				if (ConnectionManager.getInstance().isOnline(contactId)) writeProxy.write(connectionManager.getSocketId(contactId),
-						new Contacts(Arrays.asList(PersistenceManager.getInstance().getUserById(userID).toCommon())));
+						Arrays.asList(PersistenceManager.getInstance().getUserById(userID).toCommon()));
 				break;
 			default:
 				System.err.printf("Received %s with an unsupported operation.%n", evt);
diff --git a/src/main/java/envoy/server/processors/ContactsRequestEventProcessor.java b/src/main/java/envoy/server/processors/ContactsRequestEventProcessor.java
index 7b137f8..b1330c9 100755
--- a/src/main/java/envoy/server/processors/ContactsRequestEventProcessor.java
+++ b/src/main/java/envoy/server/processors/ContactsRequestEventProcessor.java
@@ -3,9 +3,9 @@ package envoy.server.processors;
 import java.io.IOException;
 import java.util.stream.Collectors;
 
-import envoy.data.Contacts;
-import envoy.event.ContactSearchRequest;
-import envoy.event.ContactSearchResult;
+import envoy.data.Contact;
+import envoy.event.contact.ContactSearchRequest;
+import envoy.event.contact.ContactSearchResult;
 import envoy.server.data.PersistenceManager;
 import envoy.server.data.User;
 import envoy.server.net.ConnectionManager;
@@ -23,7 +23,7 @@ import envoy.server.net.ObjectWriteProxy;
 public class ContactsRequestEventProcessor implements ObjectProcessor<ContactSearchRequest> {
 
 	/**
-	 * Writes a {@link Contacts} list to the client containing all {@link User}s
+	 * Writes a list of contacts to the client containing all {@link Contact}s
 	 * matching the search phrase contained inside the request. The client and their
 	 * contacts are excluded from the result.
 	 *
diff --git a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
index 523dce3..faa9f6c 100755
--- a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
+++ b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
@@ -1,16 +1,11 @@
 package envoy.server.processors;
 
 import java.io.IOException;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Date;
-import java.util.InputMismatchException;
-import java.util.List;
+import java.util.*;
 import java.util.stream.Collectors;
 
 import javax.persistence.NoResultException;
 
-import envoy.data.Contacts;
 import envoy.data.LoginCredentials;
 import envoy.data.Message.MessageStatus;
 import envoy.data.User;
@@ -57,8 +52,8 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 		UserStatusChangeProcessor.updateUserStatus(user);
 
 		// Create contacts
-		Contacts contacts = new Contacts(user.getContacts().stream().map(envoy.server.data.User::toCommon).collect(Collectors.toList()));
-		contacts.getContacts().add(user.toCommon());
+		var contacts = user.getContacts().stream().map(envoy.server.data.Contact::toCommon).collect(Collectors.toList());
+		contacts.add(user.toCommon());
 
 		// Complete handshake
 		System.out.println("Sending user...");
@@ -143,7 +138,7 @@ public class LoginCredentialProcessor implements ObjectProcessor<LoginCredential
 			user.setLastSeen(new Date());
 			user.setStatus(User.UserStatus.ONLINE);
 			user.setPasswordHash(credentials.getPasswordHash());
-			user.setContacts(new ArrayList<>());
+			user.setContacts(new HashSet<>());
 			persistenceManager.addContact(user);
 			return user;
 		}
diff --git a/src/main/java/envoy/server/processors/MessageProcessor.java b/src/main/java/envoy/server/processors/MessageProcessor.java
index 5e8d7f0..fd41a87 100755
--- a/src/main/java/envoy/server/processors/MessageProcessor.java
+++ b/src/main/java/envoy/server/processors/MessageProcessor.java
@@ -43,7 +43,7 @@ public class MessageProcessor implements ObjectProcessor<Message> {
 			}
 		} else {
 			System.out.println("The received message is a group message.");
-			final var	members		= PersistenceManager.getInstance().getGroupById(message.getRecipientID()).getMembers();
+			final var	members		= PersistenceManager.getInstance().getGroupById(message.getRecipientID()).getContacts();
 			final var	generator	= IDGeneratorRequestProcessor.createIDGenerator(members.size());
 			members.forEach(user -> {
 				envoy.data.Message returnMessage = new MessageBuilder(message.getRecipientID(), user.getID(), generator)
diff --git a/src/main/java/envoy/server/processors/NameChangeProcessor.java b/src/main/java/envoy/server/processors/NameChangeProcessor.java
new file mode 100644
index 0000000..319d302
--- /dev/null
+++ b/src/main/java/envoy/server/processors/NameChangeProcessor.java
@@ -0,0 +1,42 @@
+package envoy.server.processors;
+
+import java.io.IOException;
+
+import envoy.event.NameChangeEvent;
+import envoy.server.data.Contact;
+import envoy.server.data.PersistenceManager;
+import envoy.server.data.User;
+import envoy.server.net.ConnectionManager;
+import envoy.server.net.ObjectWriteProxy;
+
+/**
+ * Project: <strong>envoy-server-standalone</strong><br>
+ * File: <strong>NameChangeProcessor.java</strong><br>
+ * Created: <strong>26 Mar 2020</strong><br>
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Server Standalone v0.1-beta
+ */
+public class NameChangeProcessor implements ObjectProcessor<NameChangeEvent> {
+
+	@Override
+	public void process(NameChangeEvent input, long socketID, ObjectWriteProxy writeProxy) throws IOException {
+		PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
+		ConnectionManager	connectionManager	= ConnectionManager.getInstance();
+		Contact				toUpdate			= persistenceManager.getContactById(input.getID());
+		toUpdate.setName(input.get());
+		persistenceManager.updateContact(toUpdate);
+
+		// notifying online contacts of this client of his name change
+		toUpdate.getContacts().stream().filter(contact -> (contact instanceof User && connectionManager.isOnline(contact.getID()))).forEach(user -> {
+			try {
+				writeProxy.write(user.getID(), input);
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		});
+	}
+
+	@Override
+	public Class<NameChangeEvent> getInputClass() { return NameChangeEvent.class; }
+}
diff --git a/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java b/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java
index 3e1b5d3..68547fc 100755
--- a/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java
+++ b/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java
@@ -71,7 +71,7 @@ public class UserStatusChangeProcessor implements ObjectProcessor<UserStatusChan
 		UserStatusChangeEvent	evt					= new UserStatusChangeEvent(user.getID(), user.getStatus());
 		ConnectionManager		connectionManager	= ConnectionManager.getInstance();
 		try {
-			for (User contact : user.getContacts())
+			for (envoy.server.data.Contact contact : user.getContacts())
 				if (connectionManager.isOnline(contact.getID())) writeProxy.write(connectionManager.getSocketId(contact.getID()), evt);
 		} catch (IOException e) {
 			e.printStackTrace();