(Lianja) 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 Lianja Extension Download Chilkat Lianja Extension

// 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.

loSocket = createobject("CkSocket")
lnMaxWaitMs = 5000
llSuccess = loSocket.Connect("content.dropboxapi.com",443,.T.,lnMaxWaitMs)
if (llSuccess <> .T.) then
    ? loSocket.LastErrorText
    ? "Connect Fail Reason: " + str(loSocket.ConnectFailReason)
    release loSocket
    return
endif

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

loRest = createobject("CkRest")

// Tell the REST object to use the connected socket.
loRest.UseConnection(loSocket,.T.)

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

// Add request headers.
loRest.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",
// }

loJson = createobject("CkJsonObject")
loJson.AppendString("path","/Homework/lit/hamlet.xml")
loRest.AddHeader("Dropbox-API-Arg",loJson.Emit())

// Setup a file stream for the download
loFileStream = createobject("CkStream")
loFileStream.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.
lnExpectedStatus = 200
loRest.SetResponseBodyStream(lnExpectedStatus,.T.,loFileStream)

lcResponseStr = loRest.FullRequestNoBody("POST","/2/files/download")
if (loRest.LastMethodSuccess <> .T.) then
    ? loRest.LastErrorText
    release loSocket
    release loRest
    release loJson
    release loFileStream
    return
endif

// When successful, Dropbox responds with a 200 response code.
if (loRest.ResponseStatusCode <> 200) then
    // Examine the request/response to see what happened.
    ? "response status code = " + str(loRest.ResponseStatusCode)
    ? "response status text = " + loRest.ResponseStatusText
    ? "response header: " + loRest.ResponseHeader
    ? "response body (if any): " + lcResponseStr
    ? "---"
    ? "LastRequestStartLine: " + loRest.LastRequestStartLine
    ? "LastRequestHeader: " + loRest.LastRequestHeader
    release loSocket
    release loRest
    release loJson
    release loFileStream
    return
endif

// 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:
lcApiResult = loRest.ResponseHdrByName("dropbox-api-result")
? lcApiResult

// 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...
loJsonResult = createobject("CkJsonObject")
loJsonResult.EmitCompact = .F.
loJsonResult.Load(lcApiResult)
// Show the JSON pretty-printed...
? loJsonResult.Emit()

// Sample code to get data from the JSON response:
lnSize = loJsonResult.IntOf("size")
? "size = " + str(lnSize)

lcRev = loJsonResult.StringOf("rev")
? "rev = " + lcRev

lcClientModified = loJsonResult.StringOf("client_modified")
loCkdt = createobject("CkDateTime")
loCkdt.SetFromTimestamp(lcClientModified)
llBLocalTime = .T.
loDt = loCkdt.GetDtObj(llBLocalTime)
? str(loDt.Day) + "/" + str(loDt.Month) + "/" + str(loDt.Year) + " " + str(loDt.Hour) + ":" + str(loDt.Minute)
release loDt


release loSocket
release loRest
release loJson
release loFileStream
release loJsonResult
release loCkdt