mirror of
https://github.com/JoelBender/bacpypes
synced 2025-09-28 22:15:23 +08:00
152 lines
5.4 KiB
ReStructuredText
152 lines
5.4 KiB
ReStructuredText
Sample 2 - Who-Is/I-Am Counter
|
|
==============================
|
|
|
|
This sample application builds on the first sample by overriding the default
|
|
processing for Who-Is and I-Am requests, counting them, then continuing on
|
|
with the regular processing.
|
|
|
|
The description of this sample will be about the parts that are different from
|
|
sample 1.
|
|
|
|
.. note::
|
|
|
|
New in 0.15! As you've seen reading :ref:`Capabilities`, the new API allows
|
|
mixing functionnality to application more easily. In fact, by default,
|
|
inheriting from :class:`app.BISimpleApplication` includes
|
|
:class:`service.device.WhoIsIAmServices` and
|
|
:class:`service.device.ReadWritePropertyServices` capabilities.
|
|
|
|
Counters
|
|
--------
|
|
|
|
Python has a excellent *defaultdict* datatype from the *collections* module
|
|
that is perfect for this application. It is very easy to use::
|
|
|
|
>>> from collections import defaultdict
|
|
>>> x = defaultdict(int)
|
|
|
|
The essential idea is that you can treat some key as having a default value
|
|
if it doesn't exist, so rather than doing this::
|
|
|
|
>>> x['a'] = x.get('a', 0) + 1
|
|
|
|
You can do this::
|
|
|
|
>>> x['a'] += 1
|
|
|
|
Processing Service Requests
|
|
---------------------------
|
|
|
|
When an instance of the :class:`app.Application` receives a request it attempts
|
|
to look up a function based on the message. So when a WhoIsRequest APDU is
|
|
received, there should be a do_WhoIsRequest function. In fact,
|
|
:class:`services.device.WhoIsIAmServices` provides this function. For the sake
|
|
of this sample, we will override it so we can count requests.
|
|
|
|
The beginning is going to be standard boiler plate function header::
|
|
|
|
def do_WhoIsRequest(self, apdu):
|
|
"""Respond to a Who-Is request."""
|
|
if _debug: SampleApplication._debug("do_WhoIsRequest %r", apdu)
|
|
|
|
The middle is going to process the data in the request::
|
|
|
|
# build a key from the source and parameters
|
|
key = (str(apdu.pduSource),
|
|
apdu.deviceInstanceRangeLowLimit,
|
|
apdu.deviceInstanceRangeHighLimit,
|
|
)
|
|
|
|
# count the times this has been received
|
|
who_is_counter[key] += 1
|
|
|
|
And the end of the function is going to call back to the standard application
|
|
processing::
|
|
|
|
# pass back to the default implementation
|
|
BIPSimpleApplication.do_WhoIsRequest(self, apdu)
|
|
|
|
The do_IAmRequest function is similar::
|
|
|
|
def do_IAmRequest(self, apdu):
|
|
"""Given an I-Am request, cache it."""
|
|
if _debug: SampleApplication._debug("do_IAmRequest %r", apdu)
|
|
|
|
It uses a diferent key, but counts them the same::
|
|
|
|
# build a key from the source, just use the instance number
|
|
key = (str(apdu.pduSource),
|
|
apdu.iAmDeviceIdentifier[1],
|
|
)
|
|
|
|
# count the times this has been received
|
|
i_am_counter[key] += 1
|
|
|
|
And has an identical call to the base class::
|
|
|
|
# pass back to the default implementation
|
|
BIPSimpleApplication.do_IAmRequest(self, apdu)
|
|
|
|
Printing Results
|
|
----------------
|
|
|
|
By building the key out of elements in a useful order, it is simple enough
|
|
to sort the dictionary items and print them out, and being able to unpack
|
|
the key in the for loop is a nice feature of Python::
|
|
|
|
print("----- Who Is -----")
|
|
for (src, lowlim, hilim), count in sorted(who_is_counter.items()):
|
|
print("%-20s %8s %8s %4d" % (src, lowlim, hilim, count))
|
|
print("")
|
|
|
|
Pairing up the requests and responses can be a useful exercize, but in most
|
|
cases the I-Am response from a device will be a unicast message directly back
|
|
to the requestor, so relying on broadcast traffic to analyze device and
|
|
address binding is not as useful as it used to be.
|
|
|
|
Running the Application
|
|
-----------------------
|
|
|
|
::
|
|
|
|
$ python WhoIsIAmApplication.py --debug __main__
|
|
|
|
DEBUG:__main__:initialization
|
|
DEBUG:__main__: - args: Namespace(buggers=False, color=False, debug=['__main__'], ini=<class 'bacpypes.consolelogging.ini'>)
|
|
DEBUG:__main__.WhoIsIAmApplication:__init__ <bacpypes.app.LocalDeviceObject object at 0x7f596a817a90> '192.168.87.59/24'
|
|
DEBUG:__main__: - services_supported: <bacpypes.basetypes.ServicesSupported object at 0x7f59685cbe90>
|
|
DEBUG:__main__:running
|
|
|
|
Let it run for a minute, then Press <ctrl-C> to end it. It will output its results.::
|
|
|
|
DEBUG:__main__.WhoIsIAmApplication:do_WhoIsRequest <bacpypes.apdu.WhoIsRequest(8) instance at 0x7f7ca6792510>
|
|
<bacpypes.apdu.WhoIsRequest(8) instance at 0x7f7ca6792510>
|
|
pduSource = <Address 192.168.87.115>
|
|
pduDestination = <GlobalBroadcast *:*>
|
|
pduExpectingReply = False
|
|
pduNetworkPriority = 0
|
|
apduType = 1
|
|
apduService = 8
|
|
deviceInstanceRangeLowLimit = 59L
|
|
deviceInstanceRangeHighLimit = 59L
|
|
pduData = x''
|
|
[clipped...]
|
|
DEBUG:__main__:fini
|
|
----- Who Is -----
|
|
10001:0x0040ae007e01 1 1 1
|
|
10001:0x0040ae007e01 9830 9830 1
|
|
10001:0x005008067649 536 536 1
|
|
10001:0x005008067649 2323 2323 1
|
|
192.168.87.115 9 9 3
|
|
192.168.87.115 59 59 1
|
|
192.168.87.115 226 226 3
|
|
192.168.87.115 900 900 2
|
|
192.168.87.115 11189 11189 3
|
|
192.168.87.115 80403 80403 3
|
|
192.168.87.115 110900 110900 3
|
|
192.168.87.115 4194302 4194302 2
|
|
192.168.87.48 3300 3300 1
|
|
|
|
----- I Am -----
|
|
|