this.transcript.traceDebugging("opening file with path `%s` with extra `%{object}` " , path, extra);
final CallbackCompletion<? extends eu.mosaic_cloud.connectors.dfs.hdfs.IHadoopDfsFileConnector> completion = this.connector.openFile(path, mode);
final DeferredFuture<HadoopDfsFileConnector<TFileContext, TFileExtra>> future = (DeferredFuture) DeferredFuture.create (GenericDfsFileConnector.class);
completion.observe(new CallbackCompletionObserver() {
@Override
public CallbackCompletion<Void> completed(CallbackCompletion<?> completion_) {
assert (completion == completion_);