private OMElement createEnvelope(String fileName) throws Exception {
DataHandler expectedDH;
OMFactory fac = OMAbstractFactory.getOMFactory();
OMNamespace omNs = fac.createOMNamespace("http://example.org/mtom/data", "x");
OMElement data = fac.createOMElement("Data", omNs);
File dataFile = new File(fileName);
FileDataSource dataSource = new FileDataSource(dataFile);
expectedDH = new DataHandler(dataSource);
OMText textData = fac.createText(expectedDH, true);