use generic handler

include/sp/protocol/ConcreteMessage.h

@@ -33,6 +33,22 @@ class ConcreteMessage : public MessageBase {
 		return details::WriteMessage(m_Data);
 	}
 
+	DataType* operator*() {
+		return &m_Data;
+	}
+
+	DataType* operator->() {
+		return &m_Data;
+	}
+
+	const DataType* operator*() const {
+		return &m_Data;
+	}
+
+	const DataType* operator->() const {
+		return &m_Data;
+	}
+
   private:
 	DataType m_Data;
 };