[PythonCE] How do you develop on the PocketPC?

[Luke Dunstan]

----- Original Message ----- 
From: "Thomas Heller" <theller at python.net>
To: <pythonce at python.org>
Sent: Wednesday, January 11, 2006 3:42 PM
Subject: Re: [PythonCE] How do you develop on the PocketPC?


> "Luke Dunstan" <coder_infidel at hotmail.com> writes:
>
>> ----- Original Message ----- 
>> From: "Thomas Heller" <theller at python.net>
>> To: <pythonce at python.org>
>> Sent: Monday, January 09, 2006 10:42 PM
>> Subject: Re: [PythonCE] How do you develop on the PocketPC?
>>
>> I have noticed that IE works on the PDA when cradled, but I know that
>> ActiveSync is not providing a real network adapter on the PC side
>> because an extra IP does not appear in the output of 'ipconfig'. This
>> prevents running TCP listen servers on the PDA but it is true that
>> your method works nicely in this case.
>
> Luke,
>
> Do you know of any other way except TCP/IP to establish a two-way
> communication between the desktop and the PDA?
>
> Thomas

One way I know is using the CeRapiInvoke() API, which is a kind of remote 
procedure call:

STDAPI_( HRESULT ) CeRapiInvoke(
  LPCWSTR pDllPath,
  LPCWSTR pFunctionName,
  DWORD cbInput,
  BYTE * pInput,
  DWORD * pcbOutput,
  BYTE ** ppOutput,
  IRAPIStream ** ppIRAPIStream,
  DWORD dwReserved
);

You can specify a DLL and function name and the device-side part of RAPI 
will load the DLL and call the function, but it must have the following 
prototype (see also wincerapi.py):

typedef HRESULT (STDAPICALLTYPE RAPIEXT)(
  DWORD cbInput,
  BYTE * pInput,
  DWORD * pcbOutput,
  BYTE ** ppOutput,
  IRAPIStream * pIRAPIStream
);

In block mode (ppIRAPIStream == NULL) you can simply pass a block of data in 
each direction. The interesting part is that if you pass a pointer then you 
will receive a IRAPIStream* that allows the device and PC to communicate in 
both directions similar to a socket.

I have tested this in one direction only using the CeInvoke sample from the 
Pocket PC 2003 SDK, and I also tested replacing the desktop-side program 
with a Python script. However, so far this API does not seem robust; for 
example if the device-side DLL releases the stream then IRAPIStream::Read() 
seems to block forever in the desktop program. The CeInvoke sample handles 
this by sending a command over the stream to let the desktop know that it 
has finished, but to my mind it is a hack because it would be like sending a 
disconnect command over a TCP socket and relying on that to shut down the 
other end. The function IRAPIStream::SetRapiStat can supposedly set a 
timeout for Read() but so far I can't get it to work. There is a two-way 
stream sample in an MSDN KB article that I have yet to try.

For creating development tools there is also the possibility of using the 
Platform Manager APIs, which are installed and used by eMbedded Visual C++ 
to communicate with the remote debugger, among other things. Platform 
Manager supports multiple "transports" including TCP/IP and ActiveSync and 
you can even create your own transport. I haven't actually tried using it 
yet though :-).

Luke