+--- 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;
+ }
+ }
+