removed the broadcast checkbox

Added a Handshake method for the communicator
The academy will try to handshake regardless of the brains present
Player and Heuristic brains will send their information through the communicator but will not receive commands

unity-environment/Assets/ML-Agents/Scripts/Academy.cs

         brains = gameObject.GetComponentsInChildren<Brain>();
         InitializeAcademy();
 
+        communicator = new ExternalCommunicator(this);
+        if (!communicator.CommunicatorHandShake())
+        {
+            communicator = null;
+        }
+
-
+            
         windowResize = true;
         done = true;
         acceptingSteps = true;

unity-environment/Assets/ML-Agents/Scripts/Communicator.cs

     /// decisions made outside of Unity
     void SubscribeBrain(Brain brain);
 
+    /// First contact between Communicator and external process
+    bool CommunicatorHandShake();
+
     /// Implement this method to initialize the communicator
     void InitializeCommunicator();
 

unity-environment/Assets/ML-Agents/Scripts/CoreBrainExternal.cs

     {
         if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator == null)
         {
-            coord = new ExternalCommunicator(brain.gameObject.transform.parent.gameObject.GetComponent<Academy>());
-            brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator = coord;
-            coord.SubscribeBrain(brain);
+            throw new UnityAgentsException(string.Format("The brain {0} was set to" +
+                " External mode" +
+                " but Unity was unable to read the" +
+                " arguments passed at launch.", brain.gameObject.name));
+            coord = null;
-        else
+        else if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator is ExternalCommunicator)
-            if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator is ExternalCommunicator)
-            {
-                coord = (ExternalCommunicator)brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator;
-                coord.SubscribeBrain(brain);
-            }
+            coord = (ExternalCommunicator)brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator;
+            coord.SubscribeBrain(brain);
+
     }
 
     /// Uses the communicator to retrieve the actions, memories and values and
-        brain.SendActions(coord.GetDecidedAction(brain.gameObject.name));
-        brain.SendMemories(coord.GetMemories(brain.gameObject.name));
-        brain.SendValues(coord.GetValues(brain.gameObject.name));
+        if (coord != null)
+        {
+            brain.SendActions(coord.GetDecidedAction(brain.gameObject.name));
+            brain.SendMemories(coord.GetMemories(brain.gameObject.name));
+            brain.SendValues(coord.GetValues(brain.gameObject.name));
+        }
     }
 
     /// Uses the communicator to send the states, observations, rewards and
-        coord.giveBrainInfo(brain);
+        if (coord != null)
+        {
+            coord.giveBrainInfo(brain);
+        }
     }
 
     /// Nothing needs to appear in the inspector 

unity-environment/Assets/ML-Agents/Scripts/CoreBrainHeuristic.cs

     public Brain brain;
     /**< Reference to the brain that uses this CoreBrainHeuristic */
 
-    public bool broadcast;
-    /**< If true, the brain will send states / actions / rewards through the communicator */
     ExternalCommunicator coord;
 
     public Decision decision;
     {
         decision = brain.gameObject.GetComponent<Decision>();
 
-        if (broadcast)
+        if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator == null)
-            if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator == null)
-            {
-                coord = new ExternalCommunicator(brain.gameObject.transform.parent.gameObject.GetComponent<Academy>());
-                brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator = coord;
-                coord.SubscribeBrain(brain);
-            }
-            else
-            {
-                if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator is ExternalCommunicator)
-                {
-                    coord = (ExternalCommunicator)brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator;
-                    coord.SubscribeBrain(brain);
-                }
-            }
+            coord = null;
+        }
+        else if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator is ExternalCommunicator)
+        {
+            coord = (ExternalCommunicator)brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator;
+            coord.SubscribeBrain(brain);
         }
     }
 
     /// Nothing needs to be implemented, the states are collected in DecideAction
     public void SendState()
     {
-        if (broadcast)
+        if (coord!=null)
         {
             coord.giveBrainInfo(brain);
         }
     {
 #if UNITY_EDITOR
         EditorGUILayout.LabelField("", GUI.skin.horizontalSlider);
-        broadcast = EditorGUILayout.Toggle("Broadcast", broadcast);
         if (brain.gameObject.GetComponent<Decision>() == null)
         {
             EditorGUILayout.HelpBox("You need to add a 'Decision' component to this gameObject", MessageType.Error);

unity-environment/Assets/ML-Agents/Scripts/CoreBrainPlayer.cs

         public int index;
         public float value;
     }
-
-    public bool broadcast;
-    /**< If true, the brain will send states / actions / rewards through the communicator */
+        
     ExternalCommunicator coord;
 
     [SerializeField]
     /// Nothing to implement
     public void InitializeCoreBrain()
     {
-        if (broadcast)
+        if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator == null)
+        {
+            coord = null;
+        }
+        else if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator is ExternalCommunicator)
-            if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator == null)
-            {
-                coord = new ExternalCommunicator(brain.gameObject.transform.parent.gameObject.GetComponent<Academy>());
-                brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator = coord;
-                coord.SubscribeBrain(brain);
-            }
-            else
-            {
-                if (brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator is ExternalCommunicator)
-                {
-                    coord = (ExternalCommunicator)brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator;
-                    coord.SubscribeBrain(brain);
-                }
-            }
+            coord = (ExternalCommunicator)brain.gameObject.transform.parent.gameObject.GetComponent<Academy>().communicator;
+            coord.SubscribeBrain(brain);
         }
     }
 
     /// decisions
     public void SendState()
     {
-        if (broadcast)
+        if (coord!=null)
         {
             coord.giveBrainInfo(brain);
         }
 #if UNITY_EDITOR
         EditorGUILayout.LabelField("", GUI.skin.horizontalSlider);
         SerializedObject serializedBrain = new SerializedObject(this);
-        broadcast = EditorGUILayout.Toggle("Broadcast", broadcast);
         if (brain.brainParameters.actionSpaceType == StateType.continuous)
         {
             GUILayout.Label("Edit the continuous inputs for you actions", EditorStyles.boldLabel);

unity-environment/Assets/ML-Agents/Scripts/ExternalCommunicator.cs

         hasSentState[brain.gameObject.name] = false;
     }
 
-    /// Contains the logic for the initializtation of the socket.
-    public void InitializeCommunicator()
-    {
+
+    public bool CommunicatorHandShake(){
         try
         {
             ReadArgs();
-            throw new UnityAgentsException("One of the brains was set to " +
-                "External mode or broadcast" +
-                " but Unity was unable to read the" +
-                " arguments passed at launch");
+            return false;
+        return true;
+    }
+    /// Contains the logic for the initializtation of the socket.
+    public void InitializeCommunicator()
+    {
         messageHolder = new byte[messageLength];
 
         // Create a TCP/IP  socket.