public boolean sendDownload(byte[] data, String filename) {
        DownloadService service = new DownloadService(data, filename);
        service.register();

        UrlLauncher launcher = RWT.getClient().getService(UrlLauncher.class);
        launcher.openURL(service.getURL());
        return true;
    }

    private static final class DownloadService implements ServiceHandler {

        private final byte[] data;
        private final String filename;
        private String id;

        public DownloadService(byte[] data, String filename) {
            this.data = data;
            this.filename = filename;
            this.id = calculateId();
        }

        public String getURL() {
            return RWT.getServiceManager().getServiceHandlerUrl(getId());
        }

        private String getId() {
            return id;
        }

        private String calculateId() {
            return String.valueOf(System.currentTimeMillis()) + data.length;
        }

        public boolean register() {
            try {
                RWT.getServiceManager().registerServiceHandler(getId(), this);
                return true;
            } catch (Exception e) {
                log.error("failed to register download service handler", e);
                return false;
            }
        }

        private boolean unregister() {
            try {
                RWT.getServiceManager().unregisterServiceHandler(getId());
                return true;
            } catch (Exception e) {
                log.error("failed to unregister download service handler", e);
                return false;
            }
        }

        @Override
        public void service(HttpServletRequest request, HttpServletResponse response)
                throws IOException, ServletException {
            try {
                response.setContentType("application/octet-stream");
                response.setContentLength(data.length);
                response.setHeader("Content-Disposition", "attachment; filename=\"" + filename
                        + "\"");
                response.getOutputStream().write(data);
            } catch (Exception e) {
                log.error("failed to dispatch download");
            } finally {
                unregister();
            }
        }

    }