diff --git a/android/app/src/main/java/io/v/syncslides/discovery/PresentationDiscovery.java b/android/app/src/main/java/io/v/syncslides/discovery/PresentationDiscovery.java
new file mode 100644
index 0000000..b9357ee
--- /dev/null
+++ b/android/app/src/main/java/io/v/syncslides/discovery/PresentationDiscovery.java
@@ -0,0 +1,28 @@
+// Copyright 2015 The Vanadium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package io.v.syncslides.discovery;
+
+import io.v.syncslides.model.DynamicList;
+import io.v.syncslides.model.PresentationAdvertisement;
+import io.v.v23.context.VContext;
+
+/**
+ * Handles advertising and scanning for live presentations.
+ */
+public interface PresentationDiscovery {
+    /**
+     * Finds all live presentations.  The returned list will be continually
+     * updated as new presentations start and old presentations end.
+     */
+    DynamicList<PresentationAdvertisement> scan();
+
+    /**
+     * Starts advertising a presentation.
+     * @param vContext context for the advertisement.  Client should cancel the context
+     *                 to stop advertising.
+     * @param advertisement details of the presentation.
+     */
+    void advertise(VContext vContext, PresentationAdvertisement advertisement);
+}
diff --git a/android/app/src/main/java/io/v/syncslides/model/Deck.java b/android/app/src/main/java/io/v/syncslides/model/Deck.java
new file mode 100644
index 0000000..0b214ff
--- /dev/null
+++ b/android/app/src/main/java/io/v/syncslides/model/Deck.java
@@ -0,0 +1,33 @@
+// Copyright 2015 The Vanadium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package io.v.syncslides.model;
+
+import android.graphics.Bitmap;
+
+/**
+ * A deck, aka a set of slides.
+ */
+public interface Deck {
+    /**
+     * Returns a Bitmap suitable as a thumbnail of the deck (e.g. the title
+     * slide).
+     */
+    Bitmap getThumb();
+
+    /**
+     * Returns raw thumbnail data.
+     */
+    byte[] getThumbData();
+
+    /**
+     * Returns the title of the deck.
+     */
+    String getTitle();
+
+    /**
+     * Returns the deck id.
+     */
+    String getId();
+}
diff --git a/android/app/src/main/java/io/v/syncslides/model/DynamicList.java b/android/app/src/main/java/io/v/syncslides/model/DynamicList.java
new file mode 100644
index 0000000..3eddb8f
--- /dev/null
+++ b/android/app/src/main/java/io/v/syncslides/model/DynamicList.java
@@ -0,0 +1,30 @@
+// Copyright 2015 The Vanadium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package io.v.syncslides.model;
+
+/**
+ * Provides a list of elements via an API that fits well with RecyclerView.Adapter.
+ */
+public interface DynamicList<E> {
+    /**
+     * Returns the number of items in the list.
+     */
+    int getItemCount();
+
+    /**
+     * Returns the ith item in the list.
+     */
+    E get(int i);
+
+    /**
+     * Adds a listener for changes to the list.
+     */
+    void addListener(ListListener listener);
+
+    /**
+     * Stops any subsequent notifications to the given listener.
+     */
+    void removeListener(ListListener listener);
+}
diff --git a/android/app/src/main/java/io/v/syncslides/model/ListListener.java b/android/app/src/main/java/io/v/syncslides/model/ListListener.java
new file mode 100644
index 0000000..015d621
--- /dev/null
+++ b/android/app/src/main/java/io/v/syncslides/model/ListListener.java
@@ -0,0 +1,14 @@
+// Copyright 2015 The Vanadium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package io.v.syncslides.model;
+
+/**
+ * Callbacks for list changes.
+ */
+public interface ListListener {
+    void notifyItemChanged(int position);
+    void notifyItemInserted(int position);
+    void notifyItemRemoved(int position);
+}
diff --git a/android/app/src/main/java/io/v/syncslides/model/Person.java b/android/app/src/main/java/io/v/syncslides/model/Person.java
new file mode 100644
index 0000000..0e317e9
--- /dev/null
+++ b/android/app/src/main/java/io/v/syncslides/model/Person.java
@@ -0,0 +1,36 @@
+// Copyright 2015 The Vanadium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package io.v.syncslides.model;
+
+/**
+ * Represents either an audience member or the presenter.
+ */
+public class Person {
+    String mBlessing;
+    String mName;
+
+    /**
+     * @param blessing the Vanadium blessing for this user
+     * @param name the human full name
+     */
+    public Person(String blessing, String name) {
+        mBlessing = blessing;
+        mName = name;
+    }
+
+    /**
+     * Returns the blessing for this user.
+     */
+    public String getBlessing() {
+        return mBlessing;
+    }
+
+    /**
+     * Returns the human full name.
+     */
+    public String getName() {
+        return mName;
+    }
+}
\ No newline at end of file
diff --git a/android/app/src/main/java/io/v/syncslides/model/PresentationAdvertisement.java b/android/app/src/main/java/io/v/syncslides/model/PresentationAdvertisement.java
new file mode 100644
index 0000000..4271746
--- /dev/null
+++ b/android/app/src/main/java/io/v/syncslides/model/PresentationAdvertisement.java
@@ -0,0 +1,42 @@
+// Copyright 2015 The Vanadium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package io.v.syncslides.model;
+
+/**
+ * Contains sufficient details of a live presentation such that a potential audience
+ * member could choose to join it.
+ */
+public class PresentationAdvertisement {
+    Person mPresenter;
+    Deck mDeck;
+    String mSyncgroupName;
+
+    public PresentationAdvertisement(Person presenter, Deck deck, String syncgroupName) {
+        mPresenter = presenter;
+        mDeck = deck;
+        mSyncgroupName = syncgroupName;
+    }
+
+    /**
+     * Returns the person who is presenting.
+     */
+    public Person getPresenter() {
+        return mPresenter;
+    }
+
+    /**
+     * Returns the deck being presented.
+     */
+    public Deck getDeck() {
+        return mDeck;
+    }
+
+    /**
+     * Returns the syncgroup name for this presentation.
+     */
+    public String getSyncgroupName() {
+        return mSyncgroupName;
+    }
+}