[Mobile-sig] support of the android platform

[Russell Keith-Magee]

On Thu, Apr 28, 2016 at 6:09 PM, Gabriel Pettier <gabriel.pettier at gmail.com>
wrote:

> On Thu, Apr 28, 2016 at 11:09:52AM +0200, Xavier de Gaye wrote:
>
>> On 04/28/2016 03:01 AM, Russell Keith-Magee wrote:
>>
>>> (Apologies for the personal repost - I forgot to reply-all on the first
>>> attempt)
>>>
>>> Hi Xavier,
>>>
>>> Great stuff!
>>>
>>> I’ve got a question about your experience integrating with the native
>>> Android platform APIs.
>>>
>>> Getting CPython compiled as a native binary library is a huge step, but
>>> my experience has been that bridging between binary libraries and the
>>> Java/Dalvik APIs is a painful process - JNI *exists*, but
>>> it’s *really* slow, and has some pretty harsh limitations (like the
>>> kernel-imposed JNI reference count limit).
>>>
>>> For some applications, this won’t matter - for example, if you’re
>>> treating the android device as a low power server, something that is
>>> terminal only isn’t a problem. However, if you want to write a
>>> native app, then you need to be able to create an Activity, with a View,
>>> put a Button on it, and a Layout, and so on. Have you done any exploration
>>> of the binding to these native APIs?
>>>
>>
>>
>> A first-class citizen java application embeds python using JNI. The
>> embedded
>> python accesses the android API by importing and invoking methods of an
>> android.py module.  The android.py module maps those API requests to json
>> RPC
>> calls that are sent to another java application so that they may be
>> processed
>> and their results returned.  This is the design of Scripting Layer for
>> Android
>> (SL4A) [1], a languishing project.
>>
>> IMHO you should define what 'slow' means, slow for a gaming application,
>> for
>> tracking the smartphone accelerometer or for a pyephem based application
>> that
>> brings the ephemeresis of stars and planets at your finger tip :)
>>
>> Xavier
>>
>> [1] https://github.com/damonkohler/sl4a
>>
>
> You may be interested in pyjnius[1], which, if not working around the JNI
> limitations (speed being one, but other JNI limitations for using the
> Android API is the inhability to extend java classes), makes using it with
> python a lot easier, by using Java introspection capabilities, it may not
> be the best answer if speed is the most important criteria, but i would
> advocate for reconsidering using Python on Android if that's the case.
>
> [1] https://github.com/kivy/pyjnius
>

Hi Gabriel,

I’m well aware of PyJNIus. I didn’t have a whole lot of luck with it,
mostly because of bugs/complications with Cython.

I also tried my hand at my own version that didn’t have the dependency on
Cython, and used ctypes instead:

https://github.com/pybee/rubicon-java

This has the benefit that it can be installed using a simple “pip install”.

That works, but my experience was that Android’s JNI layer really wasn’t up
to the task - hence why I asked Xavier what (if any) work he had done in
this area.

Yours,
Russ Magee %-)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/mobile-sig/attachments/20160429/94f263de/attachment.html>