diff --git a/src/main/java/envoy/server/data/Contact.java b/src/main/java/envoy/server/data/Contact.java
index b629c37..c9700d5 100644
--- a/src/main/java/envoy/server/data/Contact.java
+++ b/src/main/java/envoy/server/data/Contact.java
@@ -17,15 +17,16 @@ import javax.persistence.*;
  */
 
 @Entity
-@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
+@Table(name = "contacts")
+@Inheritance(strategy = InheritanceType.JOINED)
 public abstract class Contact {
 
 	@Id
-	@GeneratedValue(strategy = GenerationType.TABLE)
+	@GeneratedValue
 	protected long		id;
 	protected String	name;
 
-	@ManyToMany(targetEntity = Contact.class, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
+	@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
 	protected Set<Contact> contacts;
 
 	/**
diff --git a/src/main/java/envoy/server/data/Group.java b/src/main/java/envoy/server/data/Group.java
index 595b252..9c8ebf4 100644
--- a/src/main/java/envoy/server/data/Group.java
+++ b/src/main/java/envoy/server/data/Group.java
@@ -7,10 +7,8 @@ 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>
+ * Represents a group inside the database. Referred to as "server group" as
+ * opposed to "group" from Envoy Common.<br>
  * <br>
  * Project: <strong>envoy-server-standalone</strong><br>
  * File: <strong>Group.java</strong><br>
@@ -21,9 +19,19 @@ import javax.persistence.Table;
  */
 @Entity
 @Table(name = "groups")
-@NamedQuery(query = "SELECT g FROM Group g WHERE g.name = :name", name = "getGroupByName")
+@NamedQuery(
+	name = Group.findByName,
+	query = "SELECT g FROM Group g WHERRE g.name = :name"
+)
 public class Group extends Contact {
 
+	/**
+	 * Named query retrieving a group by name (parameter {@code :name}.
+	 * 
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static final String findByName = "Group.findByName";
+
 	/**
 	 * {@inheritDoc}
 	 */
diff --git a/src/main/java/envoy/server/data/GroupMessage.java b/src/main/java/envoy/server/data/GroupMessage.java
index 0d1e2bc..f952621 100644
--- a/src/main/java/envoy/server/data/GroupMessage.java
+++ b/src/main/java/envoy/server/data/GroupMessage.java
@@ -3,14 +3,7 @@ package envoy.server.data;
 import java.util.Date;
 import java.util.Map;
 
-import javax.persistence.CascadeType;
-import javax.persistence.ElementCollection;
-import javax.persistence.Entity;
-import javax.persistence.Id;
-import javax.persistence.ManyToOne;
-import javax.persistence.Table;
-import javax.persistence.Temporal;
-import javax.persistence.TemporalType;
+import javax.persistence.*;
 
 /**
  * Project: <strong>envoy-server-standalone</strong><br>
@@ -22,9 +15,7 @@ import javax.persistence.TemporalType;
  */
 
 @Entity
-@Table(name = "groupMessages")
-// @NamedQuery()
-// TODO Add Queries
+@Table(name = "group_messages")
 public class GroupMessage {
 
 	@Id
diff --git a/src/main/java/envoy/server/data/Message.java b/src/main/java/envoy/server/data/Message.java
index f82658a..470f772 100755
--- a/src/main/java/envoy/server/data/Message.java
+++ b/src/main/java/envoy/server/data/Message.java
@@ -1,15 +1,10 @@
 package envoy.server.data;
 
+import static javax.persistence.CascadeType.ALL;
+
 import java.util.Date;
 
-import javax.persistence.CascadeType;
-import javax.persistence.Entity;
-import javax.persistence.Id;
-import javax.persistence.ManyToOne;
-import javax.persistence.NamedQuery;
-import javax.persistence.Table;
-import javax.persistence.Temporal;
-import javax.persistence.TemporalType;
+import javax.persistence.*;
 
 import envoy.data.MessageBuilder;
 
@@ -29,20 +24,30 @@ import envoy.data.MessageBuilder;
 @Entity
 @Table(name = "messages")
 @NamedQuery(
+	name = Message.getPending,
 	query = "SELECT m FROM Message m WHERE (m.recipient = :user AND m.status = envoy.data.Message$MessageStatus.SENT) "
 			+ "OR (m.sender = :user) AND ((m.status = envoy.data.Message$MessageStatus.RECEIVED) AND (m.receivedDate > :lastSeen)"
-			+ "OR (m.status = envoy.data.Message$MessageStatus.READ) AND (m.readDate > :lastSeen))",
-	name = "getPendingMessages"
+			+ "OR (m.status = envoy.data.Message$MessageStatus.READ) AND (m.readDate > :lastSeen))"
 )
 public class Message {
 
+	/**
+	 * Named query retrieving pending messages for a user (parameter {@code :user})
+	 * which was last seen after a specific date (parameter {@code :lastSeen}).
+	 * 
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static final String getPending = "Message.getPending";
+	
 	@Id
 	private long id;
 
-	@ManyToOne(cascade = CascadeType.PERSIST)
+	@ManyToOne(cascade = ALL)
+	@JoinColumn
 	private User sender;
 
-	@ManyToOne(cascade = CascadeType.PERSIST)
+	@ManyToOne(cascade = ALL)
+	@JoinColumn
 	private User recipient;
 
 	@Temporal(TemporalType.TIMESTAMP)
diff --git a/src/main/java/envoy/server/data/PersistenceManager.java b/src/main/java/envoy/server/data/PersistenceManager.java
index aeecf77..d4c9929 100755
--- a/src/main/java/envoy/server/data/PersistenceManager.java
+++ b/src/main/java/envoy/server/data/PersistenceManager.java
@@ -148,7 +148,7 @@ public class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public User getUserByName(String name) {
-		return (User) entityManager.createNamedQuery("getUserByName").setParameter("name", name).getSingleResult();
+		return (User) entityManager.createNamedQuery(User.findByName).setParameter("name", name).getSingleResult();
 	}
 
 	/**
@@ -159,18 +159,7 @@ public class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public Group getGroupByName(String name) {
-		return (Group) entityManager.createNamedQuery("getGroupByName").setParameter("name", name).getSingleResult();
-	}
-
-	/**
-	 * Searched for a {@link Contact} with a specific name.
-	 *
-	 * @param name the name of the contact
-	 * @return the contact with the specified name
-	 * @since Envoy Server Standalone v0.1-alpha
-	 */
-	public Contact getContactByName(String name) {
-		return (Contact) entityManager.createNamedQuery("getContactByName").setParameter("name", name).getSingleResult();
+		return (Group) entityManager.createNamedQuery(Group.findByName).setParameter("name", name).getSingleResult();
 	}
 
 	/**
@@ -198,7 +187,8 @@ public class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public List<Message> getPendingMessages(User user) {
-		return entityManager.createNamedQuery("getPendingMessages")
+		return entityManager
+			.createNamedQuery(Message.getPending)
 			.setParameter("user", user)
 			.setParameter("lastSeen", user.getLastSeen())
 			.getResultList();
@@ -215,7 +205,8 @@ public class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public List<User> searchUsers(String searchPhrase, long userId) {
-		return entityManager.createNamedQuery("searchUsers")
+		return entityManager.createNamedQuery(
+				User.searchByName)
 			.setParameter("searchPhrase", searchPhrase + "%")
 			.setParameter("context", getUserByID(userId))
 			.getResultList();
@@ -251,7 +242,7 @@ public class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public List<User> getContacts(User user) {
-		return entityManager.createNamedQuery("getContactsOfUser").setParameter("user", user).getResultList();
+		return entityManager.createNamedQuery(User.findContacts).setParameter("user", user).getResultList();
 	}
 
 	private void persist(Object obj) {
diff --git a/src/main/java/envoy/server/data/User.java b/src/main/java/envoy/server/data/User.java
index 3fb167f..fba93ab 100755
--- a/src/main/java/envoy/server/data/User.java
+++ b/src/main/java/envoy/server/data/User.java
@@ -23,17 +23,45 @@ import envoy.data.User.UserStatus;
  */
 @Entity
 @Table(name = "users")
-@NamedQueries(
-	{ @NamedQuery(query = "SELECT u FROM User u WHERE u.name = :name", name = "getUserByName"), @NamedQuery(
-		query = "SELECT u.contacts FROM User u WHERE u = :user",
-		name = "getContactsOfUser"
+@NamedQueries({
+	@NamedQuery(
+		name = User.findByName,
+		query = "SELECT u FROM User u WHERE u.name = :name"
+	),
+	@NamedQuery(
+		name = User.findContacts,
+		query = "SELECT u.contacts FROM User u WHERE u = :user"
 	), @NamedQuery(
-		query = "SELECT u FROM User u WHERE (lower(u.name) LIKE lower(:searchPhrase) AND u <> :context AND NOT :context in elements(u.contacts))",
-		name = "searchUsers"
-	) }
-)
+		name = User.searchByName,
+		query = "SELECT u FROM User u WHERE (lower(u.name) LIKE lower(:searchPhrase) AND u <> :context AND NOT :context in elements(u.contacts))"
+	)
+})
 public class User extends Contact {
 
+	/**
+	 * Named query retrieving a user by name (parameter {@code :name}).
+	 * 
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static final String findByName = "User.findByName";
+
+	/**
+	 * Named query retrieving the contacts of a given user (parameter
+	 * {@code :user}).
+	 * 
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static final String findContacts = "User.findContacts";
+
+	/**
+	 * Named query searching for users with a name like a search phrase (parameter
+	 * {@code :searchPhrase}) that are not in the contact list of a given user
+	 * (parameter {@code :context}).
+	 * 
+	 * @since Envoy Server Standalone v0.1-beta
+	 */
+	public static final String searchByName = "User.searchByName";
+
 	private byte[] passwordHash;
 
 	@Temporal(TemporalType.TIMESTAMP)
diff --git a/src/main/resources/META-INF/persistence.xml b/src/main/resources/META-INF/persistence.xml
index 10effe7..e013e04 100755
--- a/src/main/resources/META-INF/persistence.xml
+++ b/src/main/resources/META-INF/persistence.xml
@@ -3,25 +3,25 @@
 	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
              http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
 	version="2.1">
-
 	<persistence-unit name="envoy"
 		transaction-type="RESOURCE_LOCAL">
-
 		<properties>
+		
+			<!-- JDBC -->
 			<property name="javax.persistence.jdbc.driver"
-				value="org.postgresql.Driver" /> <!-- DB Driver -->
+				value="org.postgresql.Driver" />
 			<property name="javax.persistence.jdbc.url"
-				value="jdbc:postgresql://localhost/envoy" /> <!-- BD Mane -->
-			<property name="javax.persistence.jdbc.user" value="envoy" /> <!-- DB User -->
+				value="jdbc:postgresql://localhost/envoy" />
+			<property name="javax.persistence.jdbc.user" value="envoy" />
 			<property name="javax.persistence.jdbc.password"
-				value="envoy" /> <!-- DB Password -->
+				value="envoy" />
 
+
+			<!-- Hibernate -->
 			<property name="hibernate.dialect"
-				value="org.hibernate.dialect.PostgreSQL95Dialect" /> <!-- DB Dialect -->
-			<property name="hibernate.hbm2ddl.auto" value="update" /> <!-- create / create-drop / update -->
+				value="org.hibernate.dialect.PostgreSQL95Dialect" />
+			<property name="hibernate.hbm2ddl.auto" value="update" />
 
 		</properties>
-
 	</persistence-unit>
-
 </persistence>
\ No newline at end of file