Re: Serial communication over BT using the DBus API

[Sylvain Leroux <sylvain@xxxxxxxxxxx>]

Hi Barry,

Thanks for the reply:

On 10/09/2018 10:30 PM, Barry Byford wrote:
> You might want to take a look at the Bluedot library that has used the
> DBus API to communicate over the Serial Port Profile.
> Server:
> https://github.com/martinohanlon/BlueDot/blob/master/bluedot/btcomm.py#L141
> Client:
> https://github.com/martinohanlon/BlueDot/blob/master/bluedot/btcomm.py#L466
> 
> The main section using DBus is in:
> https://github.com/martinohanlon/BlueDot/blob/master/bluedot/utils.py

I started to explore the bluedot sources. From what I understand, I need
in the shell something like the `register_spp` function
(https://github.com/martinohanlon/BlueDot/blob/master/bluedot/utils.py#L101)


I'm currently investigating how I could use `busctl` to reproduce that
behavior.

I noticed the function mostly send some XML description to the
`org.bluez.ProfileManager1` interface (see code below). There are a
couple of hard coded constants in the code, including the UUID
"00001101-0000-1000-8000-00805f9b34fb". Are those "well known" values I
can blindly use?


- Sylvain


----
def register_spp(port):

    service_record = """
    <?xml version="1.0" encoding="UTF-8" ?>
    <record>
      <attribute id="0x0001">
        <sequence>
          <uuid value="0x1101"/>
        </sequence>
      </attribute>
      <attribute id="0x0004">
        <sequence>
          <sequence>
            <uuid value="0x0100"/>
          </sequence>
          <sequence>
            <uuid value="0x0003"/>
            <uint8 value="{}" name="channel"/>
          </sequence>
        </sequence>
      </attribute>
      <attribute id="0x0100">
        <text value="Serial Port" name="name"/>
      </attribute>
    </record>
    """.format(port)

    bus = dbus.SystemBus()

    manager = dbus.Interface(bus.get_object(SERVICE_NAME, "/org/bluez"),
PROFILE_MANAGER)

    path = "/bluez"
    uuid = "00001101-0000-1000-8000-00805f9b34fb"
    opts = {
#        "AutoConnect" : True,
        "ServiceRecord" : service_record
    }

    try:
        manager.RegisterProfile(path, uuid, opts)
    except dbus.exceptions.DBusException as e:
        #the spp profile has already been registered, ignore
        if str(e) != "org.bluez.Error.AlreadyExists: Already Exists":
            raise(e)
----