Add new Server implementation
diff --git a/src/main/java/com/intel/jndn/utils/DynamicServer.java b/src/main/java/com/intel/jndn/utils/DynamicServer.java
new file mode 100644
index 0000000..8206e27
--- /dev/null
+++ b/src/main/java/com/intel/jndn/utils/DynamicServer.java
@@ -0,0 +1,40 @@
+/*
+ * jndn-utils
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU Lesser General Public License,
+ * version 3, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
+ * more details.
+ */
+package com.intel.jndn.utils;
+
+import com.intel.jndn.utils.server.RespondWithData;
+import com.intel.jndn.utils.server.Server;
+import java.io.IOException;
+
+/**
+ * Defines the API for a {@link Server} producing {@link Data} packets
+ * dynamically; in other words, when an {@link Interest} arrives, this server
+ * will run a callback to determine what packet to send back. As good practice,
+ * keep callback methods as short as possible.
+ *
+ * @author Andrew Brown <andrew.brown@intel.com>
+ */
+public interface DynamicServer extends Server {
+
+  /**
+   * Set the callback method to run when an {@link Interest} packet is passed to
+   * this server. This method should either return a {@link Data} packet that
+   * satisfies the Interest or throw an Exception to avoid sending. Calling this
+   * method a second time should replace the callback.
+   *
+   * @param callback the callback instance
+   * @throws java.io.IOException if the server fails to register a prefix
+   */
+  public void respondUsing(RespondWithData callback) throws IOException;
+}