Read the REST Response Body in Chunks

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Demonstrates Rest.ReadRespChunkBd, which reads the response body one chunk at a time, appending each chunk to a BinData. A return value of 0 signals the body is complete, while -1 indicates a read failure.

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

success = 0

set rest = CreateObject("Chilkat.Rest")
bTls = 1
bAutoReconnect = 1
success = rest.Connect("example.com",443,bTls,bAutoReconnect)
If (success = 0) Then
    outFile.WriteLine(rest.LastErrorText)
    WScript.Quit
End If

success = rest.SendReqNoBody("GET","/api/largefile")
If (success = 0) Then
    outFile.WriteLine(rest.LastErrorText)
    WScript.Quit
End If

statusCode = rest.ReadResponseHeader()
If (statusCode < 0) Then
    outFile.WriteLine(rest.LastErrorText)
    WScript.Quit
End If

'  Check for the expected success status code.  If the response is not 200, the body is likely
'  error text formatted as JSON, XML, or HTML rather than the expected content.  In that case read
'  the body as text, report it, and return.
If (statusCode <> 200) Then
    set sbError = CreateObject("Chilkat.StringBuilder")
    success = rest.ReadRespSb(sbError)
    If (success = 0) Then
        outFile.WriteLine(rest.LastErrorText)
        WScript.Quit
    End If

    outFile.WriteLine("Request failed with status code " & statusCode)
    outFile.WriteLine(sbError.GetAsString())
    WScript.Quit
End If

'  The status code is 200.  Read the response body in chunks, appending each chunk to the BinData.
'  Each call waits until at least the requested number of bytes is available, unless the response
'  ends first.  A return value of 0 means the final bytes were returned and the body is complete;
'  -1 indicates a read failure.
set bdBody = CreateObject("Chilkat.BinData")
chunkResult = rest.ReadRespChunkBd(8192,bdBody)
Do While chunkResult > 0
    chunkResult = rest.ReadRespChunkBd(8192,bdBody)
Loop
If (chunkResult < 0) Then
    outFile.WriteLine(rest.LastErrorText)
    WScript.Quit
End If

outFile.WriteLine("Received " & bdBody.NumBytes & " bytes.")

outFile.Close