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.

var
success: Integer;
rest: TChilkatRest;
bTls: Integer;
bAutoReconnect: Integer;
statusCode: Integer;
sbError: TChilkatStringBuilder;
bdBody: TChilkatBinData;
chunkResult: Integer;

begin
success := 0;

rest := TChilkatRest.Create(Self);
bTls := 1;
bAutoReconnect := 1;
success := rest.Connect('example.com',443,bTls,bAutoReconnect);
if (success = 0) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

success := rest.SendReqNoBody('GET','/api/largefile');
if (success = 0) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

statusCode := rest.ReadResponseHeader();
if (statusCode < 0) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

//  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
  begin
    sbError := TChilkatStringBuilder.Create(Self);
    success := rest.ReadRespSb(sbError.ControlInterface);
    if (success = 0) then
      begin
        Memo1.Lines.Add(rest.LastErrorText);
        Exit;
      end;
    Memo1.Lines.Add('Request failed with status code ' + IntToStr(statusCode));
    Memo1.Lines.Add(sbError.GetAsString());
    Exit;
  end;

//  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.
bdBody := TChilkatBinData.Create(Self);
chunkResult := rest.ReadRespChunkBd(8192,bdBody.ControlInterface);
while chunkResult > 0 do
  begin
    chunkResult := rest.ReadRespChunkBd(8192,bdBody.ControlInterface);
  end;

if (chunkResult < 0) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;
Memo1.Lines.Add('Received ' + IntToStr(bdBody.NumBytes) + ' bytes.');