(MFC) 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.

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkSocket.h>
#include <CkRest.h>
#include <CkJsonObject.h>
#include <CkStream.h>
#include <CkDateTime.h>
#include <CkDtObj.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // 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.

    CkSocket socket;
    int maxWaitMs = 5000;
    bool success = socket.Connect("content.dropboxapi.com",443,true,maxWaitMs);
    if (success != true) {
        strOut.append(socket.lastErrorText());
        strOut.append("\r\n");
        strOut.append("Connect Fail Reason: ");
        strOut.appendInt(socket.get_ConnectFailReason());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // Set the download bandwidth throttle rate to 50000 bytes per second.
    socket.put_BandwidthThrottleDown(50000);

    CkRest 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",
    // }

    CkJsonObject json;
    json.AppendString("path","/Homework/lit/hamlet.xml");
    rest.AddHeader("Dropbox-API-Arg",json.emit());

    // Setup a file stream for the download
    CkStream fileStream;
    fileStream.put_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.
    int expectedStatus = 200;
    rest.SetResponseBodyStream(expectedStatus,true,fileStream);

    const char *responseStr = rest.fullRequestNoBody("POST","/2/files/download");
    if (rest.get_LastMethodSuccess() != true) {
        strOut.append(rest.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    // When successful, Dropbox responds with a 200 response code.
    if (rest.get_ResponseStatusCode() != 200) {
        // Examine the request/response to see what happened.
        strOut.append("response status code = ");
        strOut.appendInt(rest.get_ResponseStatusCode());
        strOut.append("\r\n");
        strOut.append("response status text = ");
        strOut.append(rest.responseStatusText());
        strOut.append("\r\n");
        strOut.append("response header: ");
        strOut.append(rest.responseHeader());
        strOut.append("\r\n");
        strOut.append("response body (if any): ");
        strOut.append(responseStr);
        strOut.append("\r\n");
        strOut.append("---");
        strOut.append("\r\n");
        strOut.append("LastRequestStartLine: ");
        strOut.append(rest.lastRequestStartLine());
        strOut.append("\r\n");
        strOut.append("LastRequestHeader: ");
        strOut.append(rest.lastRequestHeader());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        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:
    const char *apiResult = rest.responseHdrByName("dropbox-api-result");
    strOut.append(apiResult);
    strOut.append("\r\n");

    // 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...
    CkJsonObject jsonResult;
    jsonResult.put_EmitCompact(false);
    jsonResult.Load(apiResult);
    // Show the JSON pretty-printed...
    strOut.append(jsonResult.emit());
    strOut.append("\r\n");

    // Sample code to get data from the JSON response:
    int size = jsonResult.IntOf("size");
    strOut.append("size = ");
    strOut.appendInt(size);
    strOut.append("\r\n");

    const char *rev = jsonResult.stringOf("rev");
    strOut.append("rev = ");
    strOut.append(rev);
    strOut.append("\r\n");

    const char *clientModified = jsonResult.stringOf("client_modified");
    CkDateTime ckdt;
    ckdt.SetFromTimestamp(clientModified);
    bool bLocalTime = true;
    CkDtObj *dt = ckdt.GetDtObj(bLocalTime);
    strOut.appendInt(dt->get_Day());
    strOut.append("/");
    strOut.appendInt(dt->get_Month());
    strOut.append("/");
    strOut.appendInt(dt->get_Year());
    strOut.append(" ");
    strOut.appendInt(dt->get_Hour());
    strOut.append(":");
    strOut.appendInt(dt->get_Minute());
    strOut.append("\r\n");
    delete dt;


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }