XMLHttpRequest - limitation receiving data asynchronously

  • Hello everybody.

    I'm developing a mobile QtQuick app but I encountered a general problem with the XMLHttpRequest-object:
    The app communicates with a server via a JSON API (sending JSON objects and receiving JSON objects as response).
    I use the XMLHttpRequest for asynchronous requests. There is one API call that makes the server respond with a JSON object which contains about ~500 data records (< 40 kilobytes). I can't manage to receive this response object. I checked that the server sends valid JSON data.
    Do I have to modify the HTTP headers for the app's requests?
    The mentioned response object is received successfully when the app requests the data synchronously.

    I shortened the JavaScript-method which I use to request data. The second parameter of the function is supposed to be a function to allow processing of the received data.

    function test(jsonRequest, callBack)
        var http = new XMLHttpRequest()
        var url = "http://example.com"
        var async = true
        http.open("POST", url, async)
        // send the proper header information along with the request
        http.setRequestHeader("Content-type", "application/x-www-form-urlencoded")
        http.setRequestHeader("Content-length", jsonRequest.length)
        http.setRequestHeader("Connection", "Close")
        http.onreadystatechange = function()
            if (http.readyState === XMLHttpRequest.DONE)
                if (http.status === 200)
                    var jsonResponse = http.responseText
                        if (jsonResponse == "")
                            throw "API-Error"
                        var jsonResponseObject = JSON.parse(jsonResponse)
                        if (typeof(callBack) == "function")
                            throw "no callBack-function specified: type of callBack: " + typeof(callBack)
                        if (Qt.platform.os == "windows")
                            console.log("\n\n" + e + ":\njsonRequest: >" + jsonRequest + "<\njsonResponse: >" + jsonResponse + "<\n")

    Thank you for reading.

  • Moderators

    such a feature is not part of the HTTP standard.
    Is the server application under your control? If so you need to add a custom parameter to the request to define the response limit.

  • @raven-worx
    Thank you for your answer.
    The server is not directly under my control but I can send suggestions to the person in charge. I will suggest to modify the API so one can specify the desired amount of data records per call.

Log in to reply

Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.