(Node.js) REST Download Bandwidth Throttle

Demonstrates how to use download bandwidth throttling with the REST API. This example will download a file from Drobox using a file stream, with a limit on the bandwidth that can be used for the transfer.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // A Dropbox access token should have been previously obtained.
    // Dropbox access tokens do not expire.
    // See Dropbox Access Token.

    // To use bandwidth throttling, the connection should be made using the socket API.
    // This provides numerous properties to customize the connection, such as
    // BandwidthThrottleDown, BandwidthThrottleUp, ClientIpAddress, ClintPort, Http Proxy,
    // KeepAlive, PreferIpv6, RequireSslCertVerify, SoRcvBuf, SoSndBuf, SoReuseAddr,
    // SOCKS proxy, TcpNoSDelay, TlsPinSet, TlsCipherSuite, SslAllowedCiphers, etc.

    var socket = new chilkat.Socket();
    var maxWaitMs = 5000;
    var success = socket.Connect("content.dropboxapi.com",443,true,maxWaitMs);
    if (success !== true) {
        console.log(socket.LastErrorText);
        console.log("Connect Fail Reason: " + socket.ConnectFailReason);
        return;
    }

    // Set the download bandwidth throttle rate to 50000 bytes per second.
    socket.BandwidthThrottleDown = 50000;

    var rest = new chilkat.Rest();

    // Tell the REST object to use the connected socket.
    rest.UseConnection(socket,true);

    // The remainder of this example is identical to the example at:
    // Dropbox Download File.

    // Add request headers.
    rest.AddHeader("Authorization","Bearer DROPBOX_ACCESS_TOKEN");

    // The download "parameters" are contained in JSON passed in an HTTP request header.
    // This is the JSON indicating the file to be downloaded:
    // { 
    //    "path": "/Homework/lit/hamlet.xml",
    // }

    var json = new chilkat.JsonObject();
    json.AppendString("path","/Homework/lit/hamlet.xml");
    rest.AddHeader("Dropbox-API-Arg",json.Emit());

    // Setup a file stream for the download
    var fileStream = new chilkat.Stream();
    fileStream.SinkFile = "qa_output/hamletFromDropbox.xml";

    // Indicate that the call to FullRequestNoBody should send the response body
    // to fileStream if the response status code is 200.
    // If a non-success response status code is received, then nothing
    // is streamed to the output file and the error response is returned by FullRequestNoBody.
    var expectedStatus = 200;
    rest.SetResponseBodyStream(expectedStatus,true,fileStream);

    var responseStr = rest.FullRequestNoBody("POST","/2/files/download");
    if (rest.LastMethodSuccess !== true) {
        console.log(rest.LastErrorText);
        return;
    }

    // When successful, Dropbox responds with a 200 response code.
    if (rest.ResponseStatusCode !== 200) {
        // Examine the request/response to see what happened.
        console.log("response status code = " + rest.ResponseStatusCode);
        console.log("response status text = " + rest.ResponseStatusText);
        console.log("response header: " + rest.ResponseHeader);
        console.log("response body (if any): " + responseStr);
        console.log("---");
        console.log("LastRequestStartLine: " + rest.LastRequestStartLine);
        console.log("LastRequestHeader: " + rest.LastRequestHeader);
        return;
    }

    // Information about the downloaded file is also available as JSON in a response header.
    // The "dropbox-api-result" response header contains the information.  For example:
    var apiResult = rest.ResponseHdrByName("dropbox-api-result");
    console.log(apiResult);

    // In this case, the pretty-formatted dropbox-api-result JSON looks like this:
    // { 
    //   "name": "hamlet.xml",
    //   "path_lower": "/homework/lit/hamlet.xml",
    //   "path_display": "/Homework/lit/hamlet.xml",
    //   "id": "id:74FkdeNuyKAAAAAAAAAAAQ",
    //   "client_modified": "2016-06-02T23:19:00Z",
    //   "server_modified": "2016-06-02T23:19:00Z",
    //   "rev": "9482db15f",
    //   "size": 279658
    // }

    // Load the JSON, pretty-print it, and demonstrate how to get some values...
    var jsonResult = new chilkat.JsonObject();
    jsonResult.EmitCompact = false;
    jsonResult.Load(apiResult);
    // Show the JSON pretty-printed...
    console.log(jsonResult.Emit());

    // Sample code to get data from the JSON response:
    var size = jsonResult.IntOf("size");
    console.log("size = " + size);

    var rev = jsonResult.StringOf("rev");
    console.log("rev = " + rev);

    var clientModified = jsonResult.StringOf("client_modified");
    var ckdt = new chilkat.CkDateTime();
    ckdt.SetFromTimestamp(clientModified);
    var bLocalTime = true;
    // dt: DtObj
    var dt = ckdt.GetDtObj(bLocalTime);
    console.log(dt.Day + "/" + dt.Month + "/" + dt.Year + " " + dt.Hour + ":" + dt.Minute);


}

chilkatExample();