On Jul 23, 2011, at 12:45 AM, Igor Russkih wrote:
> Our current idea is to keep this library running in monodroid as an android
> service (and by this share the main "heavy" buisness logic code between
> WM/android projects), and to create a UI wrapper. (it most probably will be
> in native java).
Using Mono for Android to create a UI wrapper makes sense, but why do you want
to run your library as an Android service? Android.App.Service has a main loop,
just like Android.App.Activity, and it's the _same_ main loop that activities
use. Consequently, it is _not_ the thread you want to be doing high data
throughput algorithms on that thread, as it would lock up your UI. You want to
use some background thread (e.g. a dedicated System.Threading.Thread) instead.
> Is it possible to work with android BT API directly from monodroid code?
There is an Android.Bluetooth namespace which allows use of bluetooth devices:
http://docs.mono-android.net/Android.Bluetooth
> How efficient it'll be in terms of data transfers?
I don't know. Unfortunately, you would need to profile. Furthermore, I don't
know if the emulator emulates bluetooth or not; you may need to profile on
actual hardware to see what the overhead is (and you'd probably want actual
hardware anyway to see if it's fast enough).
> I mean since monodroid creates wrappers for Input/Output-Streams (does it?)
> how well stream.read and stream.write will map data? The amounts of data is
> not high (several bytes), but the request/response rate with BT hardware is
> required to be as fast as possible. (normally its up to 50Hz). Won't
> read/write serialization between dalvik/mono be a bottleneck here?
Yes, Android.Runtime.OutputStreamInvoker.Write() will create a new Java-side
array, copy the contents of the managed array into the byte array, then invoke
the underlying Java method (which may make additional copies; who knows…).
Whether this will be an actual bottleneck or not requires profiling to answer.
:-(
> Second question is service <-> UI interaction part. Normally this is done
> with AIDL in java.. I haven't found any words on aidl support in monodroid.
> Guess it could be implemented 'manually' - is there any experience exist in
> this area?
As mentioned above, I'm not sure you want to use a Service here. That said,
there is currently no built-in support for AIDL files. If necessary, you could
probably hack something together by invoking the aidl compiler as a pre-build
step and including the Java sources (both generated and potentially
hand-written) into the final app by using the AndroidJavaSource build action,
then using Android.Runtime.JNIEnv to interact with the Java types. We intend on
improving AIDL support in a future release, but there is no timeframe.
- Jon
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