B4X

REST Download Bandwidth Throttle

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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. B4X

Dim success As Boolean = False

'  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.

Dim socket As ChilkatSocket
socket.Initialize("socket")
Dim maxWaitMs As Int = 5000
success = socket.Connect("content.dropboxapi.com", 443, True, maxWaitMs)
If success <> True Then
    Log(socket.LastErrorText)
    Log("Connect Fail Reason: " & socket.ConnectFailReason)
    Return
End If


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

Dim rest As ChilkatRest
rest.Initialize("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",
'  }

Dim json As ChilkatJsonObject
json.Initialize
json.AppendString("path", "/Homework/lit/hamlet.xml")
rest.AddHeader("Dropbox-API-Arg", json.Emit)

'  Setup a file stream for the download
Dim fileStream As ChilkatStream
fileStream.Initialize("fileStream")
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.
Dim expectedStatus As Int = 200
rest.SetResponseBodyStream(expectedStatus, True, fileStream)

Dim responseStr As String = rest.FullRequestNoBody("POST", "/2/files/download")
If rest.LastMethodSuccess = False Then
    Log(rest.LastErrorText)
    Return
End If


'  When successful, Dropbox responds with a 200 response code.
If rest.ResponseStatusCode <> 200 Then
    '  Examine the request/response to see what happened.
    Log("response status code = " & rest.ResponseStatusCode)
    Log("response status text = " & rest.ResponseStatusText)
    Log("response header: " & rest.ResponseHeader)
    Log("response body (if any): " & responseStr)
    Log("---")
    Log("LastRequestStartLine: " & rest.LastRequestStartLine)
    Log("LastRequestHeader: " & rest.LastRequestHeader)
    Return
End If


'  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:
Dim apiResult As String = rest.ResponseHdrByName("dropbox-api-result")
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...
Dim jsonResult As ChilkatJsonObject
jsonResult.Initialize
jsonResult.EmitCompact = False
jsonResult.Load(apiResult)
'  Show the JSON pretty-printed...
Log(jsonResult.Emit)

'  Sample code to get data from the JSON response:
Dim size As Int = jsonResult.IntOf("size")
Log("size = " & size)

Dim rev As String = jsonResult.StringOf("rev")
Log("rev = " & rev)

Dim clientModified As String = jsonResult.StringOf("client_modified")
Dim ckdt As ChilkatDateTime
ckdt.Initialize
ckdt.SetFromTimestamp(clientModified)
Dim bLocalTime As Boolean = True
Dim dt As ChilkatDtObj
dt.Initialize
ckdt.ToDtObj(bLocalTime, dt)

Log(dt.Day & "/" & dt.Month & "/" & dt.Year & " " & dt.Hour & ":" & dt.Minute)