String href = getOption(_href).getString();
String base = getOption(_href).getBaseURI().toASCIIString();
try {
DataStore store = runtime.getDataStore();
URI id = store.writeEntry(href, base, contentType, new DataWriter() {
public void store(OutputStream out) throws IOException {
try {
provider.format(source.read(),out,contentType);
} catch(SaxonApiException e) {
throw new IOException(e);