B4X

REST Receive Response in Chunks

See more REST Examples

Demonstrates how to receive a REST HTTP response in chunks.

Note: This example requires Chilkat 10.1.0 or greater.

B4X

Dim success As Boolean = False

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

Dim rest As ChilkatRest
rest.Initialize("rest")

'  Connect to the web server
Dim bTls As Boolean = True
Dim port As Int = 443
Dim bAutoReconnect As Boolean = True
success = rest.Connect("chilkatsoft.com", port, bTls, bAutoReconnect)
If success = False Then
    Log(rest.LastErrorText)
    Return
End If


'  Send the request.
'  This can be *any* kind of request: POST, GET, PUT, etc. using *any* of the Chilkat REST methods that send requests.
'  For this example, we'll just GET a simple XML document that is about 274K in size.

success = rest.SendReqNoBody("GET", "/hamlet.xml")
If success = False Then
    Log(rest.LastErrorText)
    Return
End If


'  Get the response header.
Dim statusCode As Int = rest.ReadResponseHeader
If statusCode < 0 Then
    Log(rest.LastErrorText)
    Return
End If


Log("response status code = " & statusCode)

Dim outputFile As String = "c:/temp/qa_output/hamlet.xml"

Dim fac As ChilkatFileAccess
fac.Initialize
success = fac.OpenForWrite(outputFile)
If statusCode < 0 Then
    Log(fac.LastErrorText)
    Return
End If


'  Get the response in chunks.
'  (Note: There are more efficient ways to simply download a file from a web server, such as by calling Chilkat's Http.Download method.
'  The purpose of this method is to show how to receive a response chunk-by-chunk.)
Dim bd As ChilkatBinData
bd.Initialize
Dim status As Int = 1
Do While status = 1
    '  Read a minimum of 16000 bytes.
    '  Note: Because of TLS message lengths, or the possibility of the response being either compressed (gzip/deflate) or in the HTTP chunked encoding,
    '  the amount of data received in each call can be greater than the specified min size.
    '  Chilkat will return from the call as soon as it has received an amount equal to or more than the specified size,
    '  except for the very last chunk, which can be less that the min size or even 0 bytes.

    '  The status will be one of three values:
    '  -1 = error
    '  0 = received the last chunk of the response.
    '  1 = received a chunk, and more chunks are coming..

    '  The received data is *appended* to the contents of the BinData object.
    status = rest.ReadRespChunkBd(16000, bd)
    If status >= 0 Then
        Log("Received chunk: " & bd.NumBytes & " bytes")
        fac.FileWriteBd(bd, 0, 0)
        bd.Clear
    End If

Loop

fac.FileClose

Log("Success.")