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 success As Boolean = False

Dim rest As ChilkatRest
rest.Initialize("rest")
Dim bTls As Boolean = True
Dim bAutoReconnect As Boolean = True
success = rest.Connect("example.com", 443, bTls, bAutoReconnect)
If success = False Then
    Log(rest.LastErrorText)
    Return
End If


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


Dim statusCode As Int = rest.ReadResponseHeader
If statusCode < 0 Then
    Log(rest.LastErrorText)
    Return
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
    Dim sbError As ChilkatStringBuilder
    sbError.Initialize
    success = rest.ReadRespSb(sbError)
    If success = False Then
        Log(rest.LastErrorText)
        Return
    End If

    Log("Request failed with status code " & statusCode)
    Log(sbError.GetAsString)
    Return
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.
Dim bdBody As ChilkatBinData
bdBody.Initialize
Dim chunkResult As Int = rest.ReadRespChunkBd(8192, bdBody)
Do While chunkResult > 0
    chunkResult = rest.ReadRespChunkBd(8192, bdBody)
Loop
If chunkResult < 0 Then
    Log(rest.LastErrorText)
    Return
End If

Log("Received " & bdBody.NumBytes & " bytes.")