Steps toward support of protocol revision 22 about bacpypes

[JoelBender]

Thank you for your interest in BACpypes, and thank you for the patches.

We would like to claim protocol revision 22. Do you have any restriction in mind about this, regarding the state of the library?

Apart from encoding and decoding PDUs, I have not run a particular client or server application against any BIBBs to confirm that all of the pieces are implemented correctly. The easy ones (like the old Conformance Classes) have been used by lots of people, but I have reservations about the more advanced requirements. Client applications (A-side) are much easier to build and test than servers (B-side) which usually have lots of additional code for the real-world application.

As you probably know, the Network Port object is mandatory for any device using BACnet/IP and claiming a protocol revision superior to 19.

When the async/await features came to Python I started a re-write of the library BACpypes3 and that has an IPv4 implementation of a BACnet Application NPO. The client API is much easier to use, like await app.read_property(...), and entire chunks of code like the task manager and IO control blocks are gone. The IPv4 stack layer is stable, the IPv6 stack pieces should also be stable (slightly less confident), and the beginnings of SC (encoder/decoder layered on websockets, but not the SC-hub or SC-switch).

So I appreciate the patches and I will apply them, but the vast majority of the development will be on BACpypes3. If we can get it up-to-date with the 2020 publication that would be a great victory!

We have discovered that some of its property types are not encoded as described in the standard, because Wireshark was unable to decode them.

I consider that a pretty bad problem, thank you for the patch, and I'll port the fix into BACpypes3 if its needed.

First, do you still maintain the implementation in py25 directory.

No, I stopped updating it when it was no longer easily available. With the docker world, maybe images like the ones here can be used and could come back to life...interesting thought.

I have found discrepancies between enumerations and other type declarations in this directory and in the other ones.

Yep, I'm not surprised, and there might be substantial differences in the supported services as well.

I have created the following patches for all three implementations.

Thank you!

[JoelBender]

These patches have been applied and are released in 0.18.7 and in BACpypes3 0.0.73. Thank you again!