On a valid RomInfo Object received, Start the Downloader AsyncTask to download the update zip file from server, the doInBackground() method will have pseudo code as follows:

DownloaderAsyncTask.java

private int doInBackground(Void... notused) {
final File dest = new File("/cache/update.zip");
InputStream is = null;
      OutputStream os = null;
try {
URL getUrl = new URL(romInfo.url);
destFile.getAbsolutePath());
            URLConnection conn = getUrl.openConnection();
conn.connect();
            is = new BufferedInputStream(conn.getInputStream());
            os = new FileOutputStream(destFile);
            byte[] buf = new byte[4096];
            int nRead = -1;
            int totalRead = 0;
            while ((nRead = is.read(buf)) != -1) {
                  os.write(buf, 0, nRead);
                  totalRead += nRead;
            }
  	// Verify Md5 checksum here
	} catch (Exception e) {
                e.printStackTrace();
                destFile.delete();
      } finally {
           if (is != null) {
             try { is.close(); }
             catch (Exception e) { }
           }
           if (os != null) {
             try { os.flush(); os.close(); }
             catch (Exception e) { }
           }
       }
	return 0;
}