The code for my forthcoming article on Microsoft Bluetooth Stack inquiry and discovery (remember, inquiry is for devices and discovery is for services) is ready. Apart from inquiring the available devices, it also discovers the existing services and lists the SDP record contents.
After being able to find a device with the service you want to consume, you can connect to that device using Windows Sockets. The reverse process involves publishing a service for other devices to consume and to serve requests using WS. Unfortunately the SDK has no means (nor explanation) on how to create an SDP record. Platform Builder users have the BTHNSCREATE sample to play with, but what about us, mere SDK users? Looks like Microsoft thinks this is something that should only concern people designing new Windows CE or Windows Mobile devices. I sincerely hope not and I'd rather think this is a design oversight. Why would I need such a thing?
Well, one of my plans is to provide P2P support for my products. If you look around the newsgroups you will see lots of people asking for an SDF-only synchronization package. This will require that two SDF files can "talk" to one another. I already support having a PC talk to an SDF file on a device, but what about having one device talk to another? A year ago I actually achieved this using WiFi, but this is not the correct protocol for ad-hoc P2P scenarios - Bluetooth is better. So if I want to support this scenario, I must publish a new Bluetooth service. Yes, of course I could use emulated COM ports and the code already supports serial communications. But I want the real thing: a dedicated service with its own GUID.
So how am I going to circumvent this? Most likely I will use Doug Boling's solution: use a templated SDP record and fill in the gaps (not nice, I know). What really bugs me is that the Widcomm stack makes it so much easier to publish a new service...
Azure IoT DevKit – External Connectivity
1 month ago