Develop Reference

Heavily confused by win32api + COM and an answer from SO

From my other question here on SO, I asked how to retrieve the current playing song from Windows Media Player and Zune, I got an answer from a c++ dev who gave me an explanation of how I would do this for WMP.
However, I am no C++ dev, nor am I very experienced with the pywin32 library. And on-top of all that, the documentation on all this (especially concerning WMP) is horrible.
Therefor, I need your help understanding how I would do the following in Python.
Source
I have working code in C++ to print the name of media currently
playing in WMP. It's a simple console application (78 lines of code).
Steps:
1) implements a basic COM object implementing IUnknown, IOleClientSite, IServiceProvider and IWMPRemoteMediaServices. This is
straightforward (sort of, your mileage may vary) using the ATL
template CComObjectRootEx. The only methods needing (simple) code are
IServiceProvider::QueryService and
IWMPRemoteMediaServices::GetServiceType. All other methods may return
E_NOTIMPL
2) Instantiate the "WMPlayer.OCX" COM object (in my case, via CoCreateInstance)
3) Retrieve from the object an IOleObject interface pointer via QueryInterface
4) Instanciate an object from the class seen in 1) (I use the CComObject<>::CreateInstance template)
5) Use the SetClientSite method from the interface you got at 3), passing a pointer to your OleClientSite implementation.
6) During the SetClientSite call, WMP will callback you: fisrt asking for an IServiceProvider interface pointer, second calling the
QueryService method, asking for an IWMPRemoteMediaServices interface
pointer. Return your implementation of IWMPRemoteMediaServices and,
third, you will be called again via GetServiceType. You must then
return "Remote". You are now connected to the WMP running instance
7) Query the COM object for an IWMPMedia interface pointer
8) If 7) didn't gave NULL, read the the IWMPMedia::name property.
9) DONE
All the above was tested with VS2010 / Windows Seven, and with WMP
running (if there is no Media Player process running, just do
nothing).
I don't know if yoy can/want to implement COM interface and object in
Python. If you are interested by my C++ code, let me know. You could
use that code in a C++ DLL, and then call it from python.
I know a little bit about the win32api.
At the first step, I really don't know what to do, googling IOleClientSite results in the msdn documentation, it's an interface. However, that's where I get stuck already. I can't find anything (might just be my horrendous googling skills) on working with these things in Python.
The second step:
WMP = win32com.client.Dispatch("WMPlayer.OCX")
Alright, that's doable.
On to the third step. QueryInterface -
"regardless of the object you have, you can always call its QueryInterface() method to obtain a new interface, such as IStream."
source
However, not for me. As I understand his explanation, I think it means that every com object sort of "inherits" three methods from IUnknown, one of which is QueryInterface, however this does not seem the case since calling QueryInterface on my WMP object fails miserably. (Object has no attribute 'QueryInterface')
I could ramble on, but I believe you got the point, I have no idea how to work with this. Can anyone help me out with this one? Preferably with code examples, but resources/documentation is welcome too.

Almost final answser but CAN'T finish.
I seems that pythoncom can't be used to implement custom Interface without the help of a C++ module.
Here is an answser from Mark Hammon (Mon, 13 Jan 2003): How to create COM Servers with IID_IDTExtensibility2 interface
Sorry - you are SOL. To support arbitary interfaces, you need C++
support, in the form of an extension module. There is a new "Univgw"
that may help you out, but I dont know much about this
I am not able to find anything about that "Univgw" thing...
The comtypes python module is intended to resolve the problem, and I found links saying it does, but I can't make it works with my fresh new Python 3.3. It's Python 2.x code. comtypes seems outdated and unmaintained.
Step 1 OK for IOleClientSite and IServiceProvider, KO for IWMPRemoteMediaServices
Step 2, 3, 4 and 5 OK
Step 6, 7 and 8 can't be implemented without IWMPRemoteMediaServices :-(
disclaimer: complete newbie in Python, please don't yell
import pythoncom
import win32com.client as wc
from win32com.axcontrol import axcontrol
import win32com.server as ws
from win32com.server import util
from win32com.server.exception import COMException
import winerror
import pywintypes
# Windows Media Player Custom Interface IWMPRemoteMediaServices
IWMPRemoteMediaServices = pywintypes.IID("{CBB92747-741F-44FE-AB5B-F1A48F3B2A59}")
class OleClientSite:
_public_methods_ = [ 'SaveObject', 'GetMoniker', 'GetContainer', 'ShowObject', 'OnShowWindow', 'RequestNewObjectLayout', 'QueryService' ]
_com_interfaces_ = [ axcontrol.IID_IOleClientSite, pythoncom.IID_IServiceProvider ]
def SaveObject(self):
print("SaveObject")
raise COMException(hresult=winerror.E_NOTIMPL)
def GetMoniker(self, dwAssign, dwWhichMoniker):
print("GetMoniker ")
raise COMException(hresult=winerror.E_NOTIMPL)
def GetContainer(self):
print("GetContainer")
raise COMException(hresult=winerror.E_NOTIMPL)
def ShowObject(self):
print("ShowObject")
raise COMException(hresult=winerror.E_NOTIMPL)
def OnShowWindow(self, fShow):
print("ShowObject" + str(fShow))
raise COMException(hresult=winerror.E_NOTIMPL)
def RequestNewObjectLayout(self):
print("RequestNewObjectLayout")
raise COMException(hresult=winerror.E_NOTIMPL)
def QueryService(self, guidService, riid):
print("QueryService",guidService,riid)
if riid == IWMPRemoteMediaServices:
print("Known Requested IID, but can't implement!")
raise COMException(hresult=winerror.E_NOINTERFACE)
else:
print("Requested IID is not IWMPRemoteMediaServices" )
raise COMException(hresult=winerror.E_NOINTERFACE)
if __name__=='__main__':
wmp = wc.Dispatch("WMPlayer.OCX")
IOO = wmp._oleobj_.QueryInterface(axcontrol.IID_IOleObject)
pyOCS = OleClientSite()
comOCS = ws.util.wrap(pyOCS, axcontrol.IID_IOleClientSite)
IOO.SetClientSite(comOCS)

Python network bandwidth monitor

I am developing a program in python, and one element tells the user how much bandwidth they have used since the program has opened (not just within the program, but regular web browsing while the program has been opened). The output should be displayed in GTK
Is there anything in existence, if not can you point me in the right direction. It seems like i would have to edit an existing proxy script like pythonproxy, but i can't see how i would use it.
Thanks,

For my task I wrote very simple solution using psutil:
import time
import psutil
def main():
old_value = 0
while True:
new_value = psutil.net_io_counters().bytes_sent + psutil.net_io_counters().bytes_recv
if old_value:
send_stat(new_value - old_value)
old_value = new_value
time.sleep(1)
def convert_to_gbit(value):
return value/1024./1024./1024.*8
def send_stat(value):
print ("%0.3f" % convert_to_gbit(value))
main()

import time
def get_bytes(t, iface='wlan0'):
with open('/sys/class/net/' + iface + '/statistics/' + t + '_bytes', 'r') as f:
data = f.read();
return int(data)
while(True):
tx1 = get_bytes('tx')
rx1 = get_bytes('rx')
time.sleep(1)
tx2 = get_bytes('tx')
rx2 = get_bytes('rx')
tx_speed = round((tx2 - tx1)/1000000.0, 4)
rx_speed = round((rx2 - rx1)/1000000.0, 4)
print("TX: %fMbps RX: %fMbps") % (tx_speed, rx_speed)
should be work

Well, not quiet sure if there is something in existence (written in python) but you may want to have a look at the following.
Bandwidth Monitoring (Not really an active project but may give you an idea).
Munin Monitoring (A pearl based Network Monitoring Project)
ntop (written in C/C++, based on libpcap)
Also just to give you pointers if you are looking to do something on your own, one way could be to count and store packets using sudo cat /proc/net/dev

A proxy would only cover network applications that were configured to use it. You could set, e.g. a web browser to use a proxy, but what happens when your proxy exits?
I think the best thing to do is to hook in lower down the stack. There is a program that does this already, iftop. http://en.wikipedia.org/wiki/Iftop
You could start by reading the source code of iftop, perhaps wrap that into a Python C extension. Or rewrite iftop to log data to disk and read it from Python.

Would something like WireShark (https://wiki.wireshark.org/FrontPage) do the trick? I am tackling a similar problem now, and am inclined to use pyshark, a WireShark/TShark wrapper, for the task. That way you can get capture file info readily.

suds throwing error 'type not found' consuming SOAP service

I am consuming a SOAP webservice with suds (0.4). The WSDL I am using throws an error
>>> import uuid
>>> from suds.client import Client
>>> wsdl = 'https://toolkit.dnb.com/locked/resource/docs/TransactionAndMessageDefinition/ProductList.wsdl'
>>> client = Client(wsdl)
The service I am consuming expects one parameter productListRequest, which is a complex type where you put UserId, Password and a complex type of ProductListInput.
I fill these with:
>>> productListRequest = client.factory.create('productListRequest')
>>> productListRequest.UserId = 'myusername'
>>> productListRequest.Password = 'mypassword'
>>> productListRequest.TRNUID = uuid.uuid4()
>>> ProductListInput = client.factory.create('ProductListInput')
>>> ProductListInput.DnB_DUNS_Number = ''
>>> ProductListInput.Product = 'Product Name'
>>> ProductListInput.CountryCode = 'IT'
>>> ProductListInput.TradeUp = ''
>>> ProductListInput.Reason = ''
>>> productListRequest.ProductListInput = ProductListInput
But whenever I am calling the service:
>>> print client.service.ws_ProductList(productListRequest)
I get Type not found: 'ArrayOfUPD_FLDSItem'
I am really stuck here. I have googled this error for 2 days and honestly I do not know what to do! Maybe someone with a deeper understanding of WSDL and suds can help.
So my questions:
Is this WSDL, which I am consuming proper defined? (If it is proper defined, I will report it to the suds
maintainers)
If this WSDL is not proper defined, is there a workaround (e.g.
suds schema doctor) to fix it on suds site?
Is there a alternative Python library, which I should use?

Suds is currently the best choice for WSDL consumption in Python. Unfortunately WSDL itself is such a complex mess that making good out of it is difficult.
Luckily Suds come with extensive logging capabilities which you can use to debug the problem and this is the first step of solving it. This earlier question answers how to enable it:
How can I output what SUDs is generating/receiving?
However, giving a complete answer for the type error would require seeing extensive logging output and/or source code, so I suggest you somehow try to narrow down the problem. To make the problem ultimately solvable a sample (non-working) schema and Python code would be nice.
(The error might hint that there is some subschema / external schema defined / missing which Suds cannot load for reason X)

At first:
It does not make sense to call the product list without a DUNS-Number. The transaction gives all avaliable products to a given DUNS. If the DUNS number is left empty, you will only get a field list of the product you stated (assuming you put a valid product name into your call, not "product name").
BUT:
Even by putting all parameters in, I ran into the same problem and was not able to solve it, either.
Check with DnB and make them correct the WSDL - their WSDLs are quite buggy: Note that they have simply forgotten a whole transaction in the WSDL implementation (prodOrderRequest_3 for retrieving data from the toolkit archive)
My solution is to use the XML-Version of the Toolkit for this and the other mentioned transaction. Unfortunately.

Parsing atom response from InsertCalendar in Python on GAE (Calendar API)

Using the GData Calendar API via App Engine in Python, when you create an event there are handy little helper methods to parse the response:
new_event = calendar_service.InsertEvent(event, '/calendar/feeds/default/private/full')
helper = new_event.GetEditLink().href
When you create a new calendar:
new_calendar = gd_client.InsertCalendar(new_calendar=calendar)
I was wondering if there might be related methods that I just can't find in the documentation (or that are--perhaps--undocumented)?
I need to store the new calendar's ID in the datastore, so I would like something along the lines of:
new_calendar = gd_client.InsertCalendar(new_calendar=calendar)
new_calendar.getGroupLink().href
In my code, the calendar is being created, and G is returning the Atom response with a 201, but before I get into using elementtree or atom.parse to extract the desired element, I was hoping someone here might be able to help.
Many thanks in advance :)

I've never used the GData API, so I could be wrong, but...
It looks like GetLink() will return the link object for any specified rel. Seems like GetEditLink() just calls GetLink(), passing in the rel of the Edit link. So you should be able to call GetLink() on the response from InsertCalendar(), and pass in the rel of the Group link.
Here's the pydoc info that I used to figure this out: http://gdata-python-client.googlecode.com/svn/trunk/pydocs/gdata.calendar_resource.data.html

Discovery of web services using Python

I have several devices on a network. I am trying to use a library to discover the presence and itentity of these devices using Python script, the devices all have a web service. My question is, are there any modules that would help me with this problem as the only module I have found is ws-discovery for Python?
And if this is the only module does anyone have any example Python script using ws-discovery?
Thanks for any help.

Unfortunately I've never used ws-discovery myself, but there seems to be a Python project which implements it:
https://pypi.org/project/WSDiscovery/
From their documentation here's a short example on how to use it:
wsd = WSDiscovery()
wsd.start()
ttype = QName("abc", "def")
ttype1 = QName("namespace", "myTestService")
scope1 = Scope("http://myscope")
ttype2 = QName("namespace", "myOtherTestService_type1")
scope2 = Scope("http://other_scope")
xAddr = "localhost:8080/abc"
wsd.publishService(types=[ttype], scopes=[scope2], xAddrs=[xAddr])
ret = wsd.searchServices()
for service in ret:
print service.getEPR() + ":" + service.getXAddrs()[0]
wsd.stop()

Are you tied to ws-discovery? If not, you might want to consider the Bonjour protocol, aka ZeroConf and DNS-SD. The protocol is relatively widely implemented. I've never used python to do the advertising or discovery but there is a project that implements an API: http://code.google.com/p/pybonjour/
As I said, I have no direct experience with this project and merely point it out as an alternative to ws-discovery.