+
+class message {
+public:
+ enum message_type { INFO, CREDIT, LOAD, CTRL_CLOSE, DATA_CLOSE };
+
+ message(message_type t, double a): type(t), amount(a) { }
+
+ message_type get_type() const { return type; }
+ double get_amount() const { return amount; }
+
+ std::string to_string();
+
+private:
+ message_type type;
+ double amount;
+};