如何使用累积事件处理脚本将十六进制转换为ASCII

Question

我有一个模拟器，它像IoT设备一样工作。该设备将十六进制值发送到c8y UI应用程序，在发送十六进制之前，我们需要在c8y UI屏幕上转换ASCII值。

@Name("createdSchema")
create schema UplinkUpdateEvent (
     msg      Number,
     time     Date,
     msgid    string
);

create expression string hexToNum(value)[

   function format(hexValue){

    var hex  = hexValue.toString();
    var str = '';
    for (var n = 0; n < hex.length; n += 2) {
        str += parseInt(hex.substr(n, 2), 16);
    }
    return str;
  };
   format(value);
];


@Name("UplinkUpdateEvent")``
insert into UplinkUpdateEvent
select
    event.event.source.value as msgid,
    event.event.time as time,
    hexToNum(getString(event, "objectResourceValue")) as msg
from EventCreated event
where event.event.type.startsWith("c8y_UpLin");

预期结果将为9（十六进制）-> 36（ASCII）