diff --git a/app/build.gradle b/app/build.gradle
index d5e0dd5..ff60256 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -73,7 +73,7 @@ check.configure {
 dependencies {
 
     // Depend on the core project for XMPP related stuff
-    implementation project(':core')
+    implementation project(':core-old')
 
     implementation "io.requery:requery-android:$requeryVersion"
     implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.41'
diff --git a/core-old/.gitignore b/core-old/.gitignore
new file mode 100644
index 0000000..796b96d
--- /dev/null
+++ b/core-old/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/core-old/build.gradle b/core-old/build.gradle
new file mode 100644
index 0000000..6ecb6fa
--- /dev/null
+++ b/core-old/build.gradle
@@ -0,0 +1,45 @@
+apply plugin: 'java-library'
+
+// Add the generated folder to the source directories so that we can work with generated classes
+// This is apparently necessary for use with requery.
+sourceSets {
+    main.java.srcDirs += "${buildDir}/generated/sources/annotationProcessor/java/main/"
+}
+
+dependencies {
+
+    api project(':entity') // Entities
+    api project(':repository') // Repository
+    api project(":thread_utils")
+
+    // Smack
+    // Not all of those are needed, but it may be a good idea to define those versions explicitly
+    api "org.igniterealtime.smack:smack-core:$smackCoreVersion"
+    api "org.igniterealtime.smack:smack-experimental:$smackExperimentalVersion"
+    api "org.igniterealtime.smack:smack-extensions:$smackExtensionsVersion"
+    api "org.igniterealtime.smack:smack-im:$smackImVersion"
+    api "org.igniterealtime.smack:smack-tcp:$smackTcpVersion"
+
+    // api "org.igniterealtime.smack:smack-omemo:$smackOmemoVersion"
+    // api "org.igniterealtime.smack:smack-omemo-signal:$smackOmemoSignalVersion"
+    // api "org.igniterealtime.smack:smack-openpgp:$smackOpenpgpVersion"
+    // api "org.igniterealtime.smack:smack-resolver-minidns:$smackResolverMiniDnsVersion"
+
+
+    // RxJava2
+    api "io.reactivex.rxjava2:rxjava:$rxJava2Version"
+
+    // Dagger 2 for dependency injection
+    implementation "com.google.dagger:dagger:$daggerVersion"
+    annotationProcessor "com.google.dagger:dagger-compiler:$daggerVersion"
+
+    // Requery ORM
+    api "io.requery:requery:$requeryVersion"
+    annotationProcessor "io.requery:requery-processor:$requeryVersion"
+
+    // JUnit for testing
+    testImplementation "junit:junit:$junitVersion"
+}
+
+sourceCompatibility = "8"
+targetCompatibility = "8"
diff --git a/core/src/main/java/org/mercury_im/messenger/core/NotificationManager.java b/core-old/src/main/java/org/mercury_im/messenger/core/NotificationManager.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/NotificationManager.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/NotificationManager.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/centers/ConnectionCenter.java b/core-old/src/main/java/org/mercury_im/messenger/core/centers/ConnectionCenter.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/centers/ConnectionCenter.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/centers/ConnectionCenter.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/centers/ContactCenter.java b/core-old/src/main/java/org/mercury_im/messenger/core/centers/ContactCenter.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/centers/ContactCenter.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/centers/ContactCenter.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/centers/MessageCenter.java b/core-old/src/main/java/org/mercury_im/messenger/core/centers/MessageCenter.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/centers/MessageCenter.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/centers/MessageCenter.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/connection/ConnectionState.java b/core-old/src/main/java/org/mercury_im/messenger/core/connection/ConnectionState.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/connection/ConnectionState.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/connection/ConnectionState.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/connection/MercuryConfiguration.java b/core-old/src/main/java/org/mercury_im/messenger/core/connection/MercuryConfiguration.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/connection/MercuryConfiguration.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/connection/MercuryConfiguration.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/connection/MercuryConnection.java b/core-old/src/main/java/org/mercury_im/messenger/core/connection/MercuryConnection.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/connection/MercuryConnection.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/connection/MercuryConnection.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/di/CenterModule.java b/core-old/src/main/java/org/mercury_im/messenger/core/di/CenterModule.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/di/CenterModule.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/di/CenterModule.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/di/XmppComponent.java b/core-old/src/main/java/org/mercury_im/messenger/core/di/XmppComponent.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/di/XmppComponent.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/di/XmppComponent.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/stores/EntityCapsStore.java b/core-old/src/main/java/org/mercury_im/messenger/core/stores/EntityCapsStore.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/stores/EntityCapsStore.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/stores/EntityCapsStore.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/stores/PlainMessageStore.java b/core-old/src/main/java/org/mercury_im/messenger/core/stores/PlainMessageStore.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/stores/PlainMessageStore.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/stores/PlainMessageStore.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/stores/RosterStore.java b/core-old/src/main/java/org/mercury_im/messenger/core/stores/RosterStore.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/stores/RosterStore.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/stores/RosterStore.java
diff --git a/core/src/main/java/org/mercury_im/messenger/core/util/ContactNameUtil.java b/core-old/src/main/java/org/mercury_im/messenger/core/util/ContactNameUtil.java
similarity index 100%
rename from core/src/main/java/org/mercury_im/messenger/core/util/ContactNameUtil.java
rename to core-old/src/main/java/org/mercury_im/messenger/core/util/ContactNameUtil.java
diff --git a/core/build.gradle b/core/build.gradle
index 6ecb6fa..a723522 100644
--- a/core/build.gradle
+++ b/core/build.gradle
@@ -1,42 +1,18 @@
 apply plugin: 'java-library'
 
-// Add the generated folder to the source directories so that we can work with generated classes
-// This is apparently necessary for use with requery.
-sourceSets {
-    main.java.srcDirs += "${buildDir}/generated/sources/annotationProcessor/java/main/"
-}
-
 dependencies {
 
-    api project(':entity') // Entities
-    api project(':repository') // Repository
-    api project(":thread_utils")
-
-    // Smack
-    // Not all of those are needed, but it may be a good idea to define those versions explicitly
-    api "org.igniterealtime.smack:smack-core:$smackCoreVersion"
-    api "org.igniterealtime.smack:smack-experimental:$smackExperimentalVersion"
-    api "org.igniterealtime.smack:smack-extensions:$smackExtensionsVersion"
-    api "org.igniterealtime.smack:smack-im:$smackImVersion"
-    api "org.igniterealtime.smack:smack-tcp:$smackTcpVersion"
-
-    // api "org.igniterealtime.smack:smack-omemo:$smackOmemoVersion"
-    // api "org.igniterealtime.smack:smack-omemo-signal:$smackOmemoSignalVersion"
-    // api "org.igniterealtime.smack:smack-openpgp:$smackOpenpgpVersion"
-    // api "org.igniterealtime.smack:smack-resolver-minidns:$smackResolverMiniDnsVersion"
-
+    implementation project(':entity')
+    implementation project(':repository')
+    implementation project(":thread_utils")
 
     // RxJava2
-    api "io.reactivex.rxjava2:rxjava:$rxJava2Version"
+    implementation "io.reactivex.rxjava2:rxjava:$rxJava2Version"
 
     // Dagger 2 for dependency injection
     implementation "com.google.dagger:dagger:$daggerVersion"
     annotationProcessor "com.google.dagger:dagger-compiler:$daggerVersion"
 
-    // Requery ORM
-    api "io.requery:requery:$requeryVersion"
-    annotationProcessor "io.requery:requery-processor:$requeryVersion"
-
     // JUnit for testing
     testImplementation "junit:junit:$junitVersion"
 }
diff --git a/core/src/main/java/org/mercury_im/core/connection/IncomingDirectMessageListener.java b/core/src/main/java/org/mercury_im/core/connection/IncomingDirectMessageListener.java
new file mode 100644
index 0000000..eabbea5
--- /dev/null
+++ b/core/src/main/java/org/mercury_im/core/connection/IncomingDirectMessageListener.java
@@ -0,0 +1,16 @@
+package org.mercury_im.core.connection;
+
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.Address;
+import org.mercury_im.messenger.core.entity.chat.DirectChat;
+import org.mercury_im.messenger.core.entity.contact.Interlocutor;
+import org.mercury_im.messenger.core.entity.message.AbstractMessage;
+
+public interface IncomingDirectMessageListener<
+        AC extends Account<AD, ?>,
+        AD extends Address.UserAddress,
+        IL extends Interlocutor<AC, AD>> {
+
+    void onIncomingDirectMessage(AC account, DirectChat<IL, AC, AD> chat, AbstractMessage<AD, ?> message);
+
+}
diff --git a/core/src/main/java/org/mercury_im/core/connection/IncomingGroupChatMessageListener.java b/core/src/main/java/org/mercury_im/core/connection/IncomingGroupChatMessageListener.java
new file mode 100644
index 0000000..5a73d66
--- /dev/null
+++ b/core/src/main/java/org/mercury_im/core/connection/IncomingGroupChatMessageListener.java
@@ -0,0 +1,19 @@
+package org.mercury_im.core.connection;
+
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.Address;
+import org.mercury_im.messenger.core.entity.chat.DirectChat;
+import org.mercury_im.messenger.core.entity.chat.GroupChat;
+import org.mercury_im.messenger.core.entity.contact.Interlocutor;
+import org.mercury_im.messenger.core.entity.message.AbstractMessage;
+
+public interface IncomingGroupChatMessageListener<
+        AC extends Account<AD, ?>,
+        AD extends Address.UserAddress,
+        RA extends Address.RoomAddress,
+        PA extends Address.RoomParticipantAddress,
+        IL extends Interlocutor<AC, AD>> {
+
+    void onIncomingDirectMessage(AC account, GroupChat<AC, AD, RA, PA> chat, AbstractMessage<PA, ?> message);
+
+}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/DirectChat.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/DirectChat.java
deleted file mode 100644
index 2e03482..0000000
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/DirectChat.java
+++ /dev/null
@@ -1,13 +0,0 @@
-package org.mercury_im.messenger.core.entity;
-
-public interface DirectChat<
-        IL extends Interlocutor<AC, AD>,
-        AC extends Account<AD, ?>,
-        AD extends Address.UserAddress>
-        extends Chat<AC, AD> {
-
-    IL getInterlocutor();
-
-    void setInterlocutor(IL interlocutor);
-
-}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/GroupChat.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/GroupChat.java
deleted file mode 100644
index 21bfd0d..0000000
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/GroupChat.java
+++ /dev/null
@@ -1,16 +0,0 @@
-package org.mercury_im.messenger.core.entity;
-
-public interface GroupChat<
-        AC extends Account<AD, ?>,
-        AD extends Address.UserAddress,
-        RA extends Address.RoomAddress>
-        extends Chat<AC, AD> {
-
-    RA getRoomAddress();
-
-    void setRoomAddress(RA roomAddress);
-
-    String getRoomName();
-
-    void setRoomName(String roomName);
-}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/Interlocutor.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/Interlocutor.java
deleted file mode 100644
index 2e1072a..0000000
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/Interlocutor.java
+++ /dev/null
@@ -1,28 +0,0 @@
-package org.mercury_im.messenger.core.entity;
-
-/**
- * Defines a user on the network (eg. a contact, chat partner etc).
- *
- * @param <AC> Account Type
- * @param <AD> UserAddress Type
- */
-public interface Interlocutor<
-        AC extends Account<AD, ?>,
-        AD extends Address.UserAddress> {
-
-    long getId();
-
-    void setId(long id);
-
-    AC getAccount();
-
-    void setAccount(AC account);
-
-    AD getAddress();
-
-    void setAddress(AD address);
-
-    String getName();
-
-    void setName(String name);
-}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/MessageContent.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/MessageContent.java
deleted file mode 100644
index 2bb7133..0000000
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/MessageContent.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package org.mercury_im.messenger.core.entity;
-
-public interface MessageContent {
-
-    String getBody();
-
-    void setBody(String body);
-}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractDirectChat.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/AbstractDirectChat.java
similarity index 58%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractDirectChat.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/chat/AbstractDirectChat.java
index 0bcea11..aa11194 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractDirectChat.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/AbstractDirectChat.java
@@ -1,6 +1,10 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.chat;
 
-public class AbstractDirectChat<
+import org.mercury_im.messenger.core.entity.Address;
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.contact.Interlocutor;
+
+public abstract class AbstractDirectChat<
         IL extends Interlocutor<AC, AD>,
         AC extends Account<AD, ?>,
         AD extends Address.UserAddress>
@@ -9,6 +13,7 @@ public class AbstractDirectChat<
     protected long id;
     protected IL interlocutor;
     protected AC account;
+    protected ChatPreferences preferences;
 
     @Override
     public IL getInterlocutor() {
@@ -39,4 +44,14 @@ public class AbstractDirectChat<
     public void setAccount(AC account) {
         this.account = account;
     }
+
+    @Override
+    public ChatPreferences getChatPreferences() {
+        return preferences;
+    }
+
+    @Override
+    public void setChatPreferences(ChatPreferences chatPreferences) {
+        this.preferences = chatPreferences;
+    }
 }
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractGroupChat.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/AbstractGroupChat.java
similarity index 66%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractGroupChat.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/chat/AbstractGroupChat.java
index e6c99af..13d6d79 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractGroupChat.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/AbstractGroupChat.java
@@ -1,6 +1,9 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.chat;
 
-public class AbstractGroupChat<
+import org.mercury_im.messenger.core.entity.Address;
+import org.mercury_im.messenger.core.entity.Account;
+
+public abstract class AbstractGroupChat<
         AC extends Account<AD, ?>,
         AD extends Address.UserAddress,
         RA extends Address.RoomAddress>
@@ -10,6 +13,7 @@ public class AbstractGroupChat<
     private AC account;
     private RA roomAddress;
     private String roomName;
+    protected ChatPreferences preferences;
 
     @Override
     public RA getRoomAddress() {
@@ -50,4 +54,16 @@ public class AbstractGroupChat<
     public void setAccount(AC account) {
         this.account = account;
     }
+
+
+    @Override
+    public ChatPreferences getChatPreferences() {
+        return preferences;
+    }
+
+    @Override
+    public void setChatPreferences(ChatPreferences chatPreferences) {
+        this.preferences = preferences;
+    }
+
 }
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/Chat.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/Chat.java
similarity index 66%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/Chat.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/chat/Chat.java
index d5a858c..175891a 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/Chat.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/Chat.java
@@ -1,4 +1,7 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.chat;
+
+import org.mercury_im.messenger.core.entity.Address;
+import org.mercury_im.messenger.core.entity.Account;
 
 public interface Chat<
         AC extends Account<AD, ?>,
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/ChatPreferences.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/ChatPreferences.java
similarity index 94%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/ChatPreferences.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/chat/ChatPreferences.java
index af7db4b..c364525 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/ChatPreferences.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/ChatPreferences.java
@@ -1,4 +1,4 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.chat;
 
 public interface ChatPreferences {
 
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/DirectChat.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/DirectChat.java
new file mode 100644
index 0000000..088b4b7
--- /dev/null
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/DirectChat.java
@@ -0,0 +1,17 @@
+package org.mercury_im.messenger.core.entity.chat;
+
+import org.mercury_im.messenger.core.entity.Address;
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.contact.Interlocutor;
+
+public interface DirectChat<
+        IL extends Interlocutor<AC, AD, AD>,
+        AC extends Account<AD, ?>,
+        AD extends Address.UserAddress>
+        extends Chat<AC, AD> {
+
+    IL getInterlocutor();
+
+    void setInterlocutor(IL interlocutor);
+
+}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/GroupChat.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/GroupChat.java
new file mode 100644
index 0000000..dcf8806
--- /dev/null
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/chat/GroupChat.java
@@ -0,0 +1,28 @@
+package org.mercury_im.messenger.core.entity.chat;
+
+import org.mercury_im.messenger.core.entity.Address;
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.contact.Interlocutor;
+
+import java.util.Set;
+
+public interface GroupChat<
+        AC extends Account<AD, ?>,
+        AD extends Address.UserAddress,
+        RA extends Address.RoomAddress,
+        PA extends Address.RoomParticipantAddress,
+        IL extends Interlocutor<AC, PA, AD>>
+        extends Chat<AC, AD> {
+
+    Set<IL> getParticipants();
+
+    void setParticipants(Set<IL> participants);
+
+    RA getRoomAddress();
+
+    void setRoomAddress(RA roomAddress);
+
+    String getRoomName();
+
+    void setRoomName(String roomName);
+}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractInterlocutor.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/contact/AbstractInterlocutor.java
similarity index 65%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractInterlocutor.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/contact/AbstractInterlocutor.java
index b10ea15..22fe69b 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractInterlocutor.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/contact/AbstractInterlocutor.java
@@ -1,13 +1,17 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.contact;
 
-public class AbstractInterlocutor<
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.Address;
+
+public abstract class AbstractInterlocutor<
         AC extends Account<AD, ?>,
+        IA extends Address,
         AD extends Address.UserAddress>
-        implements Interlocutor<AC, AD> {
+        implements Interlocutor<AC, IA, AD> {
 
     protected long id;
     protected AC account;
-    protected AD address;
+    protected IA address;
     protected String name;
 
     @Override
@@ -31,12 +35,12 @@ public class AbstractInterlocutor<
     }
 
     @Override
-    public AD getAddress() {
+    public IA getAddress() {
         return address;
     }
 
     @Override
-    public void setAddress(AD address) {
+    public void setAddress(IA address) {
         this.address = address;
     }
 
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/Contact.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/contact/Contact.java
similarity index 81%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/Contact.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/contact/Contact.java
index d28db10..deff2e9 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/Contact.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/contact/Contact.java
@@ -1,9 +1,12 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.contact;
+
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.Address;
 
 public interface Contact<
         AC extends Account<AD, ?>,
         AD extends Address.UserAddress>
-        extends Interlocutor<AC, AD> {
+        extends Interlocutor<AC, AD, AD> {
 
     SubscriptionMode getSubscriptionMode();
 
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/contact/Interlocutor.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/contact/Interlocutor.java
new file mode 100644
index 0000000..ae2aea7
--- /dev/null
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/contact/Interlocutor.java
@@ -0,0 +1,34 @@
+package org.mercury_im.messenger.core.entity.contact;
+
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.Address;
+
+/**
+ * Defines a user on the network (eg. a contact, chat partner, group chat member etc).
+ * Basically anyone that may send you a message is an Interlocutor.
+ *
+ * @param <AC> Account Type
+ * @param <IA> Address type for the Interlocutor
+ * @param <AD> UserAddress type for the account
+ */
+public interface Interlocutor<
+        AC extends Account<AD, ?>,
+        IA extends Address,
+        AD extends Address.UserAddress> {
+
+    long getId();
+
+    void setId(long id);
+
+    AC getAccount();
+
+    void setAccount(AC account);
+
+    IA getAddress();
+
+    void setAddress(IA address);
+
+    String getName();
+
+    void setName(String name);
+}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractMessage.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/AbstractMessage.java
similarity index 73%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractMessage.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/message/AbstractMessage.java
index 7111c47..d492ce5 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/AbstractMessage.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/AbstractMessage.java
@@ -1,14 +1,20 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.message;
+
+import org.mercury_im.messenger.core.entity.Address;
 
 import java.util.Date;
+import java.util.List;
 
-public class AbstractMessage<AD extends Address, MM extends MessageMetadata> implements Message<AD, MM> {
+public abstract class AbstractMessage<
+        AD extends Address,
+        MM extends MessageMetadata>
+        implements Message<AD, MM> {
 
     protected long id;
     protected AD sender;
     protected AD recipient;
     protected Date timestamp;
-    protected String body;
+    protected List<MessagePayload> payloads;
     protected MessageDeliveryState deliveryState;
     protected MM metadata;
 
@@ -53,13 +59,13 @@ public class AbstractMessage<AD extends Address, MM extends MessageMetadata> imp
     }
 
     @Override
-    public String getBody() {
-        return body;
+    public List<MessagePayload> getMessagePayloads() {
+        return payloads;
     }
 
     @Override
-    public void setBody(String body) {
-        this.body = body;
+    public void setMessagePayloads(List<MessagePayload> list) {
+        this.payloads = list;
     }
 
     @Override
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/Message.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/Message.java
similarity index 67%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/Message.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/message/Message.java
index 0184db8..8db0112 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/Message.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/Message.java
@@ -1,6 +1,9 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.message;
+
+import org.mercury_im.messenger.core.entity.Address;
 
 import java.util.Date;
+import java.util.List;
 
 public interface Message<MA extends Address, MM extends MessageMetadata> {
 
@@ -20,9 +23,9 @@ public interface Message<MA extends Address, MM extends MessageMetadata> {
 
     void setTimestamp(Date timestamp);
 
-    String getBody();
+    List<MessagePayload> getMessagePayloads();
 
-    void setBody(String body);
+    void setMessagePayloads(List<MessagePayload> messagePayloads);
 
     MessageDeliveryState getDeliveryState();
 
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageContent.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageContent.java
new file mode 100644
index 0000000..ad462c5
--- /dev/null
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageContent.java
@@ -0,0 +1,12 @@
+package org.mercury_im.messenger.core.entity.message;
+
+public interface MessageContent {
+
+    interface Body extends MessageContent {
+
+        String getBody();
+
+        void setBody(String body);
+
+    }
+}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/MessageDeliveryState.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageDeliveryState.java
similarity index 72%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/MessageDeliveryState.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageDeliveryState.java
index 4b9a30e..dfeb33d 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/MessageDeliveryState.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageDeliveryState.java
@@ -1,4 +1,4 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.message;
 
 public enum MessageDeliveryState {
     pending_delivery,
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/MessageMetadata.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageMetadata.java
similarity index 80%
rename from entity/src/main/java/org/mercury_im/messenger/core/entity/MessageMetadata.java
rename to entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageMetadata.java
index 877b642..3f8b225 100644
--- a/entity/src/main/java/org/mercury_im/messenger/core/entity/MessageMetadata.java
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessageMetadata.java
@@ -1,4 +1,4 @@
-package org.mercury_im.messenger.core.entity;
+package org.mercury_im.messenger.core.entity.message;
 
 /**
  * Interface to allow additional, protocol specific metadata to be attached to the message.
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessagePayload.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessagePayload.java
new file mode 100644
index 0000000..125086b
--- /dev/null
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/MessagePayload.java
@@ -0,0 +1,11 @@
+package org.mercury_im.messenger.core.entity.message;
+
+import java.util.List;
+
+public interface MessagePayload {
+
+    List<MessageContent> getMessageContents();
+
+    void setMessageContents(List<MessageContent> messageContents);
+
+}
diff --git a/entity/src/main/java/org/mercury_im/messenger/core/entity/message/TextMessageContent.java b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/TextMessageContent.java
new file mode 100644
index 0000000..f013524
--- /dev/null
+++ b/entity/src/main/java/org/mercury_im/messenger/core/entity/message/TextMessageContent.java
@@ -0,0 +1,16 @@
+package org.mercury_im.messenger.core.entity.message;
+
+public class TextMessageContent implements MessageContent.Body {
+
+    private String body;
+
+    @Override
+    public String getBody() {
+        return body;
+    }
+
+    @Override
+    public void setBody(String body) {
+        this.body = body;
+    }
+}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppDirectChat.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppDirectChat.java
deleted file mode 100644
index 08f905c..0000000
--- a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppDirectChat.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package org.mercury_im.messenger.xmpp.entity;
-
-import org.mercury_im.messenger.core.entity.AbstractDirectChat;
-
-public class XmppDirectChat extends AbstractDirectChat<XmppInterlocutor, XmppAccount, XmppAddress.XmppUserAddress> {
-
-}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppGroupChat.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppGroupChat.java
deleted file mode 100644
index 74a8690..0000000
--- a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppGroupChat.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package org.mercury_im.messenger.xmpp.entity;
-
-import org.mercury_im.messenger.core.entity.AbstractGroupChat;
-
-public class XmppGroupChat extends AbstractGroupChat<XmppAccount, XmppAddress.XmppUserAddress, XmppAddress.XmppRoomAddress> {
-
-}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppInterlocutor.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppInterlocutor.java
deleted file mode 100644
index aae1fb5..0000000
--- a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppInterlocutor.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package org.mercury_im.messenger.xmpp.entity;
-
-import org.mercury_im.messenger.core.entity.AbstractInterlocutor;
-
-public class XmppInterlocutor extends AbstractInterlocutor<XmppAccount, XmppAddress.XmppUserAddress> {
-
-}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppMessage.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppMessage.java
deleted file mode 100644
index 5da2232..0000000
--- a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppMessage.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package org.mercury_im.messenger.xmpp.entity;
-
-import org.mercury_im.messenger.core.entity.AbstractMessage;
-
-public class XmppMessage extends AbstractMessage<XmppAddress, XmppMessageMetadata> {
-
-}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppMessageMetadata.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppMessageMetadata.java
deleted file mode 100644
index 6362abe..0000000
--- a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/XmppMessageMetadata.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package org.mercury_im.messenger.xmpp.entity;
-
-import org.mercury_im.messenger.core.entity.MessageMetadata;
-
-public class XmppMessageMetadata implements MessageMetadata {
-
-}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/chat/XmppDirectChat.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/chat/XmppDirectChat.java
new file mode 100644
index 0000000..07d12aa
--- /dev/null
+++ b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/chat/XmppDirectChat.java
@@ -0,0 +1,10 @@
+package org.mercury_im.messenger.xmpp.entity.chat;
+
+import org.mercury_im.messenger.core.entity.chat.AbstractDirectChat;
+import org.mercury_im.messenger.xmpp.entity.XmppAccount;
+import org.mercury_im.messenger.xmpp.entity.XmppAddress;
+import org.mercury_im.messenger.xmpp.entity.contact.XmppDirectInterlocutor;
+
+public class XmppDirectChat extends AbstractDirectChat<XmppDirectInterlocutor, XmppAccount, XmppAddress.XmppUserAddress> {
+
+}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/chat/XmppMuc.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/chat/XmppMuc.java
new file mode 100644
index 0000000..a726c01
--- /dev/null
+++ b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/chat/XmppMuc.java
@@ -0,0 +1,9 @@
+package org.mercury_im.messenger.xmpp.entity.chat;
+
+import org.mercury_im.messenger.core.entity.chat.AbstractGroupChat;
+import org.mercury_im.messenger.xmpp.entity.XmppAccount;
+import org.mercury_im.messenger.xmpp.entity.XmppAddress;
+
+public class XmppMuc extends AbstractGroupChat<XmppAccount, XmppAddress.XmppUserAddress, XmppAddress.XmppRoomAddress> {
+
+}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppContact.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppContact.java
new file mode 100644
index 0000000..35db795
--- /dev/null
+++ b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppContact.java
@@ -0,0 +1,12 @@
+package org.mercury_im.messenger.xmpp.entity.contact;
+
+import org.mercury_im.messenger.core.entity.contact.AbstractInterlocutor;
+import org.mercury_im.messenger.xmpp.entity.XmppAccount;
+import org.mercury_im.messenger.xmpp.entity.XmppAddress;
+
+public class XmppContact extends AbstractInterlocutor<
+        XmppAccount,
+        XmppAddress.XmppUserAddress,
+        XmppAddress.XmppUserAddress> {
+
+}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppDirectInterlocutor.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppDirectInterlocutor.java
new file mode 100644
index 0000000..b38df70
--- /dev/null
+++ b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppDirectInterlocutor.java
@@ -0,0 +1,12 @@
+package org.mercury_im.messenger.xmpp.entity.contact;
+
+import org.mercury_im.messenger.core.entity.contact.AbstractInterlocutor;
+import org.mercury_im.messenger.xmpp.entity.XmppAccount;
+import org.mercury_im.messenger.xmpp.entity.XmppAddress;
+
+public class XmppDirectInterlocutor extends AbstractInterlocutor<
+        XmppAccount,
+        XmppAddress.XmppUserAddress,
+        XmppAddress.XmppUserAddress> {
+
+}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppMucParticipant.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppMucParticipant.java
new file mode 100644
index 0000000..b85f9ae
--- /dev/null
+++ b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/contact/XmppMucParticipant.java
@@ -0,0 +1,12 @@
+package org.mercury_im.messenger.xmpp.entity.contact;
+
+import org.mercury_im.messenger.core.entity.contact.AbstractInterlocutor;
+import org.mercury_im.messenger.xmpp.entity.XmppAccount;
+import org.mercury_im.messenger.xmpp.entity.XmppAddress;
+
+public class XmppMucParticipant extends AbstractInterlocutor<
+        XmppAccount,
+        XmppAddress.XmppRoomParticipantAddress,
+        XmppAddress.XmppUserAddress> {
+
+}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/message/XmppMessage.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/message/XmppMessage.java
new file mode 100644
index 0000000..df185eb
--- /dev/null
+++ b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/message/XmppMessage.java
@@ -0,0 +1,32 @@
+package org.mercury_im.messenger.xmpp.entity.message;
+
+import org.mercury_im.messenger.core.entity.message.AbstractMessage;
+import org.mercury_im.messenger.xmpp.entity.XmppAddress;
+
+public final class XmppMessage extends AbstractMessage<
+        XmppAddress,
+        XmppMessageMetadata> {
+
+    private XmppMessage() {
+
+    }
+
+    public class DirectMessage extends AbstractMessage<
+            XmppAddress.XmppUserAddress,
+            XmppMessageMetadata> {
+
+    }
+
+    public class MucMessage extends AbstractMessage<
+            XmppAddress.XmppRoomParticipantAddress,
+            XmppMessageMetadata> {
+
+    }
+
+    // Maybe?
+    public class MixMessage extends AbstractMessage<
+            XmppAddress.XmppRoomParticipantAddress,
+            XmppMessageMetadata> {
+
+    }
+}
diff --git a/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/message/XmppMessageMetadata.java b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/message/XmppMessageMetadata.java
new file mode 100644
index 0000000..b607e28
--- /dev/null
+++ b/entity_xmpp/src/main/java/org/mercury_im/messenger/xmpp/entity/message/XmppMessageMetadata.java
@@ -0,0 +1,7 @@
+package org.mercury_im.messenger.xmpp.entity.message;
+
+import org.mercury_im.messenger.core.entity.message.MessageMetadata;
+
+public class XmppMessageMetadata implements MessageMetadata {
+
+}
diff --git a/repository/src/main/java/org/mercury_im/messenger/core/repository/ContactRepository.java b/repository/src/main/java/org/mercury_im/messenger/core/repository/ContactRepository.java
index ce8f651..73c4d98 100644
--- a/repository/src/main/java/org/mercury_im/messenger/core/repository/ContactRepository.java
+++ b/repository/src/main/java/org/mercury_im/messenger/core/repository/ContactRepository.java
@@ -2,7 +2,7 @@ package org.mercury_im.messenger.core.repository;
 
 import org.mercury_im.messenger.core.entity.Account;
 import org.mercury_im.messenger.core.entity.Address;
-import org.mercury_im.messenger.core.entity.Contact;
+import org.mercury_im.messenger.core.entity.contact.Contact;
 import org.mercury_im.messenger.core.util.Optional;
 
 import java.util.List;
diff --git a/repository/src/main/java/org/mercury_im/messenger/core/repository/DirectChatRepository.java b/repository/src/main/java/org/mercury_im/messenger/core/repository/DirectChatRepository.java
index 0aeefa3..2266b56 100644
--- a/repository/src/main/java/org/mercury_im/messenger/core/repository/DirectChatRepository.java
+++ b/repository/src/main/java/org/mercury_im/messenger/core/repository/DirectChatRepository.java
@@ -2,10 +2,11 @@ package org.mercury_im.messenger.core.repository;
 
 import org.mercury_im.messenger.core.entity.Account;
 import org.mercury_im.messenger.core.entity.Address;
-import org.mercury_im.messenger.core.entity.DirectChat;
-import org.mercury_im.messenger.core.entity.Interlocutor;
-import org.mercury_im.messenger.core.entity.Message;
-import org.mercury_im.messenger.core.entity.MessageMetadata;
+import org.mercury_im.messenger.core.entity.chat.DirectChat;
+import org.mercury_im.messenger.core.entity.contact.Interlocutor;
+import org.mercury_im.messenger.core.entity.message.Message;
+import org.mercury_im.messenger.core.entity.message.MessageMetadata;
+import org.mercury_im.messenger.core.entity.message.MessagePayload;
 import org.mercury_im.messenger.core.util.Optional;
 
 import java.util.List;
@@ -20,8 +21,9 @@ public interface DirectChatRepository<
         IL extends Interlocutor<AC, AD>,
         AC extends Account<AD, ?>,
         AD extends Address.UserAddress,
-        M extends Message<AD, MM>,
-        MM extends MessageMetadata> {
+        M extends Message<AD, MM, MP>,
+        MM extends MessageMetadata,
+        MP extends MessagePayload> {
 
     Single<DC> insertDirectChat(DC chat);
 
diff --git a/repository/src/main/java/org/mercury_im/messenger/core/repository/GroupChatRepository.java b/repository/src/main/java/org/mercury_im/messenger/core/repository/GroupChatRepository.java
index 5a512dc..460a00c 100644
--- a/repository/src/main/java/org/mercury_im/messenger/core/repository/GroupChatRepository.java
+++ b/repository/src/main/java/org/mercury_im/messenger/core/repository/GroupChatRepository.java
@@ -2,9 +2,10 @@ package org.mercury_im.messenger.core.repository;
 
 import org.mercury_im.messenger.core.entity.Account;
 import org.mercury_im.messenger.core.entity.Address;
-import org.mercury_im.messenger.core.entity.GroupChat;
-import org.mercury_im.messenger.core.entity.Message;
-import org.mercury_im.messenger.core.entity.MessageMetadata;
+import org.mercury_im.messenger.core.entity.chat.GroupChat;
+import org.mercury_im.messenger.core.entity.message.Message;
+import org.mercury_im.messenger.core.entity.message.MessageMetadata;
+import org.mercury_im.messenger.core.entity.message.MessagePayload;
 import org.mercury_im.messenger.core.util.Optional;
 
 import java.util.List;
@@ -19,8 +20,9 @@ public interface GroupChatRepository<
         AC extends Account<AD, ?>,
         AD extends Address.UserAddress,
         RA extends Address.RoomAddress,
-        M extends Message<AD, MM>,
-        MM extends MessageMetadata> {
+        M extends Message<AD, MM, MP>,
+        MM extends MessageMetadata,
+        MP extends MessagePayload> {
 
     Single<GC> insertGroupChat(GC chat);
 
diff --git a/settings.gradle b/settings.gradle
index ac12fbe..55efc78 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -2,9 +2,11 @@ include ':entity',
         ':entity_xmpp',
         ':repository',
         ':repository_xmpp',
+        ':core',
+        ':transport',
         ':transport_xmpp',
         ':app',
         ':thread_utils',
-        ':core'
+        ':core-old'
 
 includeBuild 'libs/Smack'
diff --git a/transport/.gitignore b/transport/.gitignore
new file mode 100644
index 0000000..796b96d
--- /dev/null
+++ b/transport/.gitignore
@@ -0,0 +1 @@
+/build
diff --git a/transport/build.gradle b/transport/build.gradle
new file mode 100644
index 0000000..a723522
--- /dev/null
+++ b/transport/build.gradle
@@ -0,0 +1,21 @@
+apply plugin: 'java-library'
+
+dependencies {
+
+    implementation project(':entity')
+    implementation project(':repository')
+    implementation project(":thread_utils")
+
+    // RxJava2
+    implementation "io.reactivex.rxjava2:rxjava:$rxJava2Version"
+
+    // Dagger 2 for dependency injection
+    implementation "com.google.dagger:dagger:$daggerVersion"
+    annotationProcessor "com.google.dagger:dagger-compiler:$daggerVersion"
+
+    // JUnit for testing
+    testImplementation "junit:junit:$junitVersion"
+}
+
+sourceCompatibility = "8"
+targetCompatibility = "8"
diff --git a/transport/src/main/java/org/mercury_im/core/Messenger.java b/transport/src/main/java/org/mercury_im/core/Messenger.java
new file mode 100644
index 0000000..6ad89fd
--- /dev/null
+++ b/transport/src/main/java/org/mercury_im/core/Messenger.java
@@ -0,0 +1,4 @@
+package org.mercury_im.core;
+
+public class Messenger {
+}
diff --git a/transport/src/main/java/org/mercury_im/core/connection/ConnectionMethod.java b/transport/src/main/java/org/mercury_im/core/connection/ConnectionMethod.java
new file mode 100644
index 0000000..96dbdcf
--- /dev/null
+++ b/transport/src/main/java/org/mercury_im/core/connection/ConnectionMethod.java
@@ -0,0 +1,14 @@
+package org.mercury_im.core.connection;
+
+import org.mercury_im.messenger.core.entity.Account;
+import org.mercury_im.messenger.core.entity.Address;
+
+public interface ConnectionMethod<
+        AC extends Account<AD, ?>,
+        AD extends Address.UserAddress> {
+
+    AC getAccount();
+
+    void setAccount(AC account);
+
+}
diff --git a/transport/src/main/java/org/mercury_im/core/connection/exception/ConnectionFailedException.java b/transport/src/main/java/org/mercury_im/core/connection/exception/ConnectionFailedException.java
new file mode 100644
index 0000000..1c64385
--- /dev/null
+++ b/transport/src/main/java/org/mercury_im/core/connection/exception/ConnectionFailedException.java
@@ -0,0 +1,6 @@
+package org.mercury_im.core.connection.exception;
+
+public class ConnectionFailedException extends Exception {
+
+    private static final long serialVersionUID = 1L;
+}