Android rest client applications-services approach @Droidcon Bucharest 2012
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This document discusses approaches for building Android REST client applications. It describes using a services approach where an activity sends a request to a service, which then performs the request in a worker thread. The service notifies listeners of the response. It recommends using loaders to handle configuration changes, where a custom loader binds to the service, performs the request, and returns the response to the activity. The service processes requests asynchronously using AsyncTask and delivers responses via a pipeline that analyzes and converts the data.
Android rest client applications-services approach @Droidcon Bucharest 2012
- 1. Android REST-client applications: services approach Sharing experience
- 2. Case
- 3. Case New startup
- 4. Case New startup
- 5. Case New startup
- 6. Case New startup
- 7. Case New startup stores posts sends provides notifies suggests
- 8. Case New startup REST
- 9. REST https://api.twitter.com/1/users/show.json?screen_name=roman_mazur { id : 14701612, name : “Roman Mazur”, location : “Ukraine, Kyiv”, … }
- 10. How to perform requests @Override public void onClick(View view) { URLConnection connection = new URL(…).openConnection(); … }
- 11. How to perform requests @Override public void onClick(View view) { URLConnection connection = new URL(…).openConnection(); … }
- 12. How to perform requests • Obviously: not in the main (GUI) thread • Using either URLConnection or HttpClient – both have pros and cons • Choose context: Activity vs. Service
- 13. Why not to use activities? • User controls activity lifecycle • When all your activities are in background your process is a candidate for killing • You’ll lose your data
- 14. Services Way • See also – Google IO 2010 session “Developing Android REST Client Applications”
- 15. Services: our first implementation Activity 1. onStart 4. performRequest ApiMethodsSupport (Helper for communication with service) 3. registerListener 2. bind 5. performRequest (using binder) Service 6. HTTP GET/POST/…
- 16. Services: our first implementation • Main problem: rotations :) – we register listener in onStart and remove it in onStop – what if response is received while we are rotating the screen?
- 17. Current implementation • Loaders! – are awesome since they are not recreated in case of configuration changes (at least in most cases) • Custom loader – binds to the service – registers listener – performs request – gets the result – unbinds
- 18. How we perform requests now @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); getLoaderManager().initLoader(1, null, this); }
- 19. How we perform requests now @Override public Loader<ResponseData<Profile>> onCreateLoader(int id, Bundle args) { return new SimpleRequestBuilder<Profile>(getActivity()) { } .setUrl("https://api.twitter.com/1/users/show.json") .addParam("screen_name", "TwitterAPI") .getLoader(); }
- 20. How we perform requests now @Override public void onLoadFinished(Loader<ResponseData<Profile>> loader, ResponseData<Profile> data) { if (data.isSuccessful()) { Profile profile = data.getModel(); text1.setText(profile.getName()); text2.setText(profile.getDescription()); } }
- 21. How we perform requests now @Override public void onLoadFinished(Loader<ResponseData<Profile>> loader, ResponseData<Profile> data) { if (data.isSuccessful()) { Profile profile = data.getModel(); text1.setText(profile.getName()); text2.setText(profile.getDescription()); } }
- 22. ResponseData • Result code • Status message • User visible message • Data
- 23. Activity Side • Request builder creates a request description • Description is passed to a service – a) as an Intent – b) with a service binder method performRequest
- 24. Service Side • Either enqueues description processing or performs it in the worker thread using AsyncTask • Request description builds URLConnection • Input thread is read, parsed; result is analyzed and then delivered to listeners
- 25. Service Side: Response Pipeline URLConnection ContentHandler Parsed object ResponseDataConverter ResponseData ContentAnalyzer Listeners Analyzed ResponseData
- 26. Conclusions • Power – requests processing can be easily managed – requests can triggered by notifications and AlarmManager • Simplicity – not much to learn if you are familiar with Android loaders • Caveats – currently not everything is easy to customize
- 27. It’s open source But we lack documentation :) http://code.google.com/p/enroscar/ and we are preparing to release it on GitHub
- 28. Thanks! Roman Mazur Head of Android Unit at Stanfy Kyiv GDD co-organizer [email protected] +Roman Mazur @roman_mazur