Add json message serializer

Basic serializer to serialize server messages to json.

lib/rex/server.rb

@@ -11,6 +11,8 @@ require_relative "server/matching_engine"
 require_relative "server/message_broker"
 require_relative "server/message_processor"
 require_relative "server/websocket_server"
+
+require_relative "server/json_message_serializer"
 module Rex
   module Server
     VERSION = "0.1.0"

lib/rex/server/json_message_serializer.rb

@@ -0,0 +1,22 @@
+module Rex
+  module Server
+    class JsonMessageSerializer
+      def serialize(obj)
+        obj = if obj.is_a?(Array)
+          {
+            type: "response",
+            name: "validation.errors",
+            data: obj.map(&:to_h)
+          }
+        else
+          {
+            type: "response",
+            name: obj.class.name.split("::").last,
+            data: obj.to_h
+          }
+        end
+        obj.to_json
+      end
+    end
+  end
+end