Question

I need to setup an in-app OBEX server on an Android 2.3 device. Using the Bluetooth Chat Sample code I was able to setup an OBEX server. However, the server needs to use a custom UUID so the service is not registered as an ‘OBEX Server’

# sdptool browse local
...(snip)...
Service Name: OBEX Object Push
Service RecHandle: 0x10000
Service Class ID List:
  UUID 128: ab123abc-1a2b-3c4d-5d7f-1234567890ab
Protocol Descriptor List:
  "L2CAP" (0x0100)
  "RFCOMM" (0x0003)
    Channel: 18

So, when I receive data, it looks like I am receiving a raw OBEX connection request:

80 00 07 10 00 04 00 00 00 00 ...(snip)... 00 00 00 (1kb file)

Is there an OBEX implementation that I can use or do I have to implement the protocol myself?

I don’t want to use the inbuilt OBEX server – this has to be in app. I have tried BlueCove but I abandoned it when I had issues registering a service.

Yes, I did see this post and read the link in it, but by golly, there must be an easier way!

Answer 1

I ended up implementing the protocol myself. It wasn’t as hairy as I imagined. Since I was expecting only a specific client to connect and I knew that the client would only be pushing one file I was able to partially implement only the sections of the protocol that I needed.

Some documentation that helped with understanding the OBEX protocol were Obex13.pdf at: http://gitorious.org/gammu/gsm-docs/trees/e5161a75fb1e1c1608959b27ae3c3940bcf0911b/standards/obex

A quick snippet of how I parsed the sockets input stream:
(Note OBEXUtils and OBEXConstants are my classes.)

try
{
    //Read all bytes passed in
    bytes = mmInStream.read(buffer);

    //Ensure we have the entire packet before we proceed
    // Packet length is in the 1st and 2nd byte
    expectedLength = OBEXUtils.bytesToShort(buffer[OBEXConstant.LENGTH_IDENTIFIER],
        buffer[OBEXConstant.LENGTH_IDENTIFIER + 1]);

    packetLength = bytes;

    //Keep reading until we get what we expect.
    while (packetLength < expectedLength)
    {
        bytes = mmInStream.read(buffer, packetLength, maxPacketSize);
        packetLength += bytes;
    }

    //Switch on Packet Header
    switch (buffer[OBEXConstant.HEADER_IDENTIFIER])
    {
        case OBEXConstant.CONNECT:
            //Parse the packet and return an acknowledgement packet
            write(OBEXConnect.parsePacket(buffer));
            break;

        case OBEXConstant.PUT:
        case OBEXConstant.PUT_FINAL:
            //Parse the PUT packet and return an acknowledgement packet
            //For Parsing PUT packets I referred to the android and bluecove implementations
            write(putPacket.appendPacket(buffer, packetLength));
            break;

        case OBEXConstant.DISCONNECT:
            //Parse the packet and return an acknowledgement packet
            write(OBEXDisconnect.parsePacket(buffer));
            break;

        case OBEXConstant.GET:
        case OBEXConstant.GET_FINAL:
        case OBEXConstant.SETPATH:
        case OBEXConstant.SETPATH_FINAL:
        case OBEXConstant.SESSION:
            //Did not implement these
            break;

        case OBEXConstant.ABORT:
            Log.w(Constant.TAG, TAG + "ABORT Request Received");
            isDisconnected = true;
            break;

        default:

            break;
    }
}
catch (final IOException e)
{
    ...(snip)...
}

Snip of OBEXConstant:

public static final byte FINAL_BIT = (byte) 0x80;

public static final byte CONNECT = 0x00 | FINAL_BIT; //*high bit always set Connect choose your partner, negotiate capabilities
public static final byte DISCONNECT = 0x01 | FINAL_BIT; //*high bit always set Disconnect signal the end of the session
public static final byte PUT = 0x02; //(0x82) Put send an object
public static final byte PUT_FINAL = PUT | FINAL_BIT;
public static final byte GET = 0x03; //(0x83) Get get an object
public static final byte GET_FINAL = GET | FINAL_BIT; //(0x83) Get get an object
public static final byte SETPATH = 0x05;
public static final byte SETPATH_FINAL = SETPATH | FINAL_BIT;
public static final byte SESSION = 0x07;
public static final byte ABORT = (byte) 0xFF;

public static final byte OBEX_RESPONSE_CONTINUE = (byte) 0x90;
public static final byte OBEX_RESPONSE_SUCCESS = (byte) 0xA0;