Question

I wrote a Delphi function retrieving a web page from another application.

This works fine when I use a file to store the information via

Result := URLDownloadToFile( nil, PChar( XmlUrl), PChar( XmlFileName_), 0, nil);

When I use an URLOpenBlocking-stream I get the correct information but the second time I do a request to the webserver I get the old page although the page has changed.

Does anybody have an idea what could be the cause ?

function MyDownloadToBlockingSteam( URL : String; Var bsXmlStr : AnsiString): LongInt;
var
  ppStream  : ActiveX.IStream;
  statstg   : TStatStg;
  dwRead    : Integer;
begin
  Result := 1;

  bsXmlStr := '';

  If (URLOpenBlockingStream(nil, PChar(URL), ppStream, 0, nil) = S_OK) then
  Begin
    // Resource protection
    try
      if (ppStream.Stat(statstg, STATFLAG_NONAME) = S_OK) then // Get the stat from the IStream interface
      begin
        if (statstg.cbSize > 0) then // Make sure size is greater than zero
        begin
          SetLength ( bsXMLStr, statstg.cbSize+1 );
          Result := ppStream.Read( @bsXMLStr[1], statstg.cbSize, @dwRead); // Read from the stream
        end;
      end;
    finally
      ppStream:=nil; // Release the IStream interface
    end;
  end;//If ..
end;

Answer 1

Consider using InternetOpenUrl() and InternetReadFile() instead. It will take a few extra lines of coding to manually accomplish the same thing that URLOpenBlockingStream() does internally for you, but InternetOpenUrl() does have a dwFlags parameter which accepts an INTERNET_FLAG_RELOAD flag to force downloading the latest data from the URL. URLOpenBlockingStream() does not have that option.