Stream large file (database) to server

Android isn't very good at base64Encoding a large file (15-20mb). My app ends up with large databases as it's a data intensive app that has to work offline. Very rarely something goes wrong and the user can't sync with the main server, in this case I need to be able to get the database sent to me to debug it.

I seem to have to base64Encode a file (as a blob) in order to xhr upload it. Is this always the case or is there a way around it (I'm sending the file to a .Net asmx webservice)?

Is it possible to stream upload a blob through xhr on Android? Does anyone have an example, the docs aren't clear in this namespace?

Maybe I can base64Encode chunks of the file blob to a text file and when that's complete, stream upload the large file, so at no point does the whole file need to be held in memory.

Any help much appreciated!

I wrote this code which will base64Encode a file of any size as it does it in chunks, may be of use to someone:

var instream = finalZip.open(Titanium.Filesystem.MODE_READ);
    var outfile = Titanium.Filesystem.getFile(Ti.Filesystem.getExternalStorageDirectory() + 'test.txt');
    if (outfile.exists()) {
        outfile.deleteFile();
    }
    var outstream = outfile.open(Titanium.Filesystem.MODE_WRITE);   
    var buffer = Titanium.createBuffer({length: 1024});
    // Read and write chunks.
    var size = 0;
    while ((size = instream.read(buffer)) > -1) {
        var str = Ti.Codec.decodeString({length:buffer.length, position:0, source:buffer});
        var encoded = Ti.Utils.base64encode(str);
        Ti.API.info('encoded.length:' + encoded.length)
        var bufferNew = Titanium.createBuffer({length:encoded.length});
        var bytes = Ti.Codec.encodeString({source:encoded.text,dest:bufferNew})
        bufferNew.length = bytes;
 
 
      outstream.write(bufferNew);
      Titanium.API.info('Wrote ' + size + ' bytes');
    }
    // Cleanup.
    instream.close();
    outstream.close();

I ended up streaming the file to the WebService like this:

var finalZip = Titanium.Filesystem.getFile(pathToYourFile);
xhr.send({data:finalZip});

This method will send the bytes as a multipart/form body but it adds 170 characters to the message body. They are supposed to be mimeType etc.. headers but they appear in the body. I add my own headers using setRequestHeader(), and then on the server where I convert the message body to a file I remove the first 170 bytes so the file is intact. Fiddler saved the day here!