--- ParaView-v4.0.1-source/ParaViewCore/ServerImplementation/Core/vtkPVMessage.proto.orig	2014-10-29 21:55:42.582965302 +0100
+++ ParaView-v4.0.1-source/ParaViewCore/ServerImplementation/Core/vtkPVMessage.proto	2014-10-29 21:58:20.865441145 +0100
@@ -62,10 +62,10 @@
 {
   extend Message {
     // The classname for the driver process i.e. the client, typically
-    required string client_class = 10;
+    optional string client_class = 10;
 
     // The classname for the process where the processing occurs
-    required string server_class = 11;
+    optional string server_class = 11;
   }
 }
 
@@ -98,8 +98,8 @@
     }
 
   extend Message {
-    required string     xml_group           = 20;
-    required string     xml_name            = 21;
+    optional string     xml_group           = 20;
+    optional string     xml_name            = 21;
     optional string     xml_sub_proxy_name  = 22;
     repeated Property   property            = 23;
     repeated SubProxy   subproxy            = 24;
@@ -204,7 +204,7 @@
   }
 
   extend Message {
-    required uint32 view      = 70;
+    optional uint32 view      = 70;
     optional double x         = 71 [default = 0];
     optional double y         = 72 [default = 0];
     optional bool   forceShow = 73 [default = false];
@@ -217,7 +217,7 @@
 message ChartViewBounds {
 
   extend Message {
-    required uint32 view  = 75;
+    optional uint32 view  = 75;
     repeated double range = 76;
   }
 }
@@ -240,8 +240,8 @@
 
 message ChatMessage {
   extend Message {
-    required uint32 author = 84;
-    required string txt    = 85;
+    optional uint32 author = 84;
+    optional string txt    = 85;
   }
 }
 
@@ -254,7 +254,7 @@
   }
 
   extend Message {
-    required QtEventType type  = 98;
+    optional QtEventType type  = 98;
   }
 }