private static XmlElement ProcessCompressed(IProcessXmlSoapClient client, TwinfieldProcessXmlService.Header header, XmlDocument input) { byte[] compressedInput = Zlib.CompressXml(input); byte[] compressedOutput = client.ProcessXmlCompressed(header, compressedInput); XmlDocument document = Zlib.DecompressXml(compressedOutput); return(document == null ? null : document.DocumentElement); }