Jersey client upload progress

Question

I have a jersey client that need to upload a file big enough to require a progress bar.
The problem is that, for an upload that requires some minutes, i see the bytes transfered to go to 100% as soon as the application has started. Then it takes some minutes to print the "on finished" string.
It is as if the bytes were sent to a buffer, and i was reading the transfert-to-the buffer speed instead of the actual upload speed. This makes the progress bar useless.

This is the very simple code:

ClientConfig config = new DefaultClientConfig();
Client client = Client.create(config);
WebResource resource = client.resource("www.myrestserver.com/uploads");
WebResource.Builder builder = resource.type(MediaType.MULTIPART_FORM_DATA_TYPE);

FormDataMultiPart multiPart = new FormDataMultiPart();
FileDataBodyPart fdbp = new FileDataBodyPart("data.zip", new File("data.zip"));
BodyPart bp = multiPart.bodyPart(fdbp);
String response = builder.post(String.class, multiPart);

To get progress state i've added a ContainerListener filter, obviouslt before calling builder.post:

final ContainerListener containerListener = new ContainerListener() {

        @Override
        public void onSent(long delta, long bytes) {
            System.out.println(delta + " : " + long);
        }

        @Override
        public void onFinish() {
            super.onFinish();
            System.out.println("on finish");
        }

    };

    OnStartConnectionListener connectionListenerFactory = new OnStartConnectionListener() {
        @Override
        public ContainerListener onStart(ClientRequest cr) {
            return containerListener;
        }

    };

    resource.addFilter(new ConnectionListenerFilter(connectionListenerFactory));

Answer 1

it should be enough to provide you own MessageBodyWriter for java.io.File which fires some events or notifies some listeners as progress changes

@Provider()
@Produces(MediaType.APPLICATION_OCTET_STREAM)
public class MyFileProvider implements MessageBodyWriter<File> {

    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return File.class.isAssignableFrom(type);
    }

    public void writeTo(File t, Class<?> type, Type genericType, Annotation annotations[], MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) throws IOException {
        InputStream in = new FileInputStream(t);
        try {
            int read;
            final byte[] data = new byte[ReaderWriter.BUFFER_SIZE];
            while ((read = in.read(data)) != -1) {
                entityStream.write(data, 0, read);
                // fire some event as progress changes
            }
        } finally {
            in.close();
        }
    }

    @Override
    public long getSize(File t, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return t.length();
    }
}

and to make your client application uses this new provider simply:

ClientConfig config = new DefaultClientConfig();
config.getClasses().add(MyFileProvider.class);

or

ClientConfig config = new DefaultClientConfig();
MyFileProvider myProvider = new MyFileProvider ();
cc.getSingletons().add(myProvider);

You would have to also include some algorithm to recognize which file is transfered when receiving progress events.

Edited:

I just found that by default HTTPUrlConnection uses buffering. And to disable buffering you could do couple of things:

1. httpUrlConnection.setChunkedStreamingMode(chunklength) - disables buffering and uses chunked transfer encoding to send request
2. httpUrlConnection.setFixedLengthStreamingMode(contentLength) - disables buffering and but ads some constraints to streaming: exact number of bytes must be sent

So I suggest the final solution to your problem uses 1st option and would look like this:

ClientConfig config = new DefaultClientConfig();
config.getClasses().add(MyFileProvider.class);
URLConnectionClientHandler clientHandler = new URLConnectionClientHandler(new HttpURLConnectionFactory() {
     @Override
     public HttpURLConnection getHttpURLConnection(URL url) throws IOException {
           HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setChunkedStreamingMode(1024);
                return connection;
            }
});
Client client = new Client(clientHandler, config);

Answer 2

In Jersey 2.X, i've used a WriterInterceptor to wrap the output stream with a subclass of Apache Commons IO CountingOutputStream that tracks the writing and notify my upload progress code (not shown).

public class UploadMonitorInterceptor implements WriterInterceptor {

    @Override
    public void aroundWriteTo(WriterInterceptorContext context) throws IOException, WebApplicationException {

        // the original outputstream jersey writes with
        final OutputStream os = context.getOutputStream();

        // you can use Jersey's target/builder properties or 
        // special headers to set identifiers of the source of the stream
        // and other info needed for progress monitoring
        String id = (String) context.getProperty("id");
        long fileSize = (long) context.getProperty("fileSize");

        // subclass of counting stream which will notify my progress
        // indicators.
        context.setOutputStream(new MyCountingOutputStream(os, id, fileSize));

        // proceed with any other interceptors
        context.proceed();
    }

}

I then registered this interceptor with the client, or with specific targets where you want to use the interceptor.