Question

问题陈述：考虑使用Express库运行REST通讯的Node js程序。有多个REST API调用，并且所有API都使用一个阻塞资源，该资源一次只能运行一个请求，例如串行端口。

我遇到这样的情况，我收到多个对API调用的并行请求，这些请求又将串行端口用于某些目的。

我如何引导来自不同方法的API调用，然后精简它，然后一个接一个地执行，然后将响应返回给相应的请求？

代码段：

/**
 * This function is a blocking function that utilizes the serial port
 */
function request_response(shield, channel, parameter, parameterValue) {
    var promise = new Promise(function (resolve, reject) {
        var commandString = modbusRTURequestGenerator.modbusRTURequestGenerator(shield, channel, parameter, data, parameterValue);
        serialOUT(commandString).then(() => {
            Promise.race([serialIN(), timeOut()]).then(results => {
                resolve(results);
            });
        });
    });
    return promise;
}

/**
 * This is a GET Request API to get the parameter values.
 */
router.get("/getParameter", function (req, res) {    
    var shield = req.query.shield;
    var channel = req.query.channel;
    var parameter = req.query.parameter;

    request_response(shield, channel, parameter, undefined).then(
        (result) => {
            res.send(result);
        });
});

/**
 * This is a POST Request API to set the parameter values.
 */
router.post("/setParameter", function (req, res) {
    var shield = req.query.shield;
    var channel = req.query.channel;
    var parameter = req.query.parameter;
    var parameterValue = req.body.value;

    request_response(shield, channel, parameter, parameterValue).then(
        (result) => {
            res.send(result);
        });
});

/**
 * This is a GET Request API for Scan functionality.
 */
router.get("/scan", function (req, res) {
    var msg = {};
    var cmds_arr = [];
    for (var i = 1; i <= constants.NUMBER_OF_SHIELDS; i++) {
        cmds_arr.push(i + "," + constants.SCAN_COMMAND_REGISTER);
    }

    asyncLoop(cmds_arr, function (item, next) {
        var params = item.split(",");
        var shield = params[0];
        var register = params[1];
        request_response(shield, undefined, register, undefined).then(
            (result) => {
                    msg[data] = result;
                    next();
                }
            });
    }, function () {
        res.send(msg);
    });
});

HTTP REST API有3种：scan，getParameter和setParameter。所有这三个都在访问request_response函数。因此，当我运行扫描API并并行触发getParameter API时，我得到了错误的结果。

在Node JS中处理多个HTTP请求

0 个答案: