@Kostya: Thanks for your answer. Based on your answer, Handler does sound better that AsyncTask for this. I looked a little bit into HandlerThread, probabaly have to try it out to understand it fully.
One question though, forgetting about the whole native thing for a moment... even if there are two Java classes (one Activity & one backend) with methods running in two threads. Can they BOTH implement listeners, hold a reference to each other & call each other's listening methods? That would make the design really tightly-coupled. Is there a design pattern to use where they both can listen to each other & call each other asynchronously - whenever needed to? On May 26, 1:07 pm, Kostya Vasilyev <kmans...@gmail.com> wrote: > I would start by wrapping some of the C++ code in Java with JNI (you > probably already have that). > > AsyncTask isn't really appropriate, because it's a task, not a process, > meaning it doesn't have a duration in time any more than necessary for one > item of work. > > You can use Handler objects, they are not necessarily tied to the UI. You'd > need two: one on the UI thread owned by the activity, one owned by the Java > wrapper of the back-end thread, and associated with that thread. > > Take a look at HandlerThread, that's the basic idea for your backend, except > you'd be calling a native method for processing messages. > > -- Kostya > > 2011/5/26 Oceanblue <ns1...@gmail.com> > > > I have an interesting design challenge: > > > I have a frontend(Activity) and a backend (written in native C/C++) > > code. The backend is a complex object which partially controls the > > flow of application & once started runs in it's own thread. So I have > > a "distributed control" scenario. > > > The Activity needs to be able to send messages asynchronously to the > > backend which then takes certain actions. But the backend also needs > > to be able to send messages asynchronously to the Activity, to which > > it responds by chnaging UI, firing methods etc. > > > Essentially what I need is a two-way listener. > > > So backend sends a message to screen (take picture, prompt user, get > > location, take another picture nowm etc) and screen does what it needs > > to do. But in addition, the screen should also be able to call the > > backend-listener to send back messages (captured camera image, system > > generated - "I got paused/destroyed" message, etc) in the callbacks of > > these events. Main problem is that this is all asynchronous. > > > Is this possible without tight-coupling? Is this even possible? > > > I have thought of Asynctask/handlers (but that's a one way street for > > informing the UI thread), observer-pattern (both objects will be > > observer/observable?) but confused on where to begin. Any thoughts, > > links would be very helpful. > > > -- > > You received this message because you are subscribed to the Google > > Groups "Android Developers" group. > > To post to this group, send email to android-developers@googlegroups.com > > To unsubscribe from this group, send email to > > android-developers+unsubscr...@googlegroups.com > > For more options, visit this group at > >http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
