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Preparing your web services for Android and your Android app for web services @Droidcon Bucharest 2012

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Presented by Auras Dumanovschi

Preparing your web services for Android and your Android app for web services @Droidcon Bucharest 2012

  1. 1. PREPARING YOUR WEBSERVICES FOR ANDROID AND THE OTHER WAY AROUND SPEAKER: AURAS DUMANOVSCHI
  2. 2. OVERVIEW● Web services: play nice with others● Response formats● Optimization● Tips● Android: using the web data● Increasing the speed of your app
  3. 3. WEB SERVICES?WHY
  4. 4. WEB SERVICES?{ ● Offloads the data gathering, transformation and storage to a powerful server. ● Can do a lot of things in a very short time ● It’s connected to a large internetWHY pipe
  5. 5. IS THERE A 2ND CHOICE?
  6. 6. IS THERE A 2ND CHOICE? Yes!
  7. 7. IS THERE A 2ND CHOICE? Yes! Where else can you get data from?
  8. 8. IS THERE A 2ND CHOICE? Yes! Where else can you get data from? Web pages
  9. 9. IS THERE A 2ND CHOICE? Yes! Where else can you get data from? Web pages That means parsing HTML client side.
  10. 10. YEAH, SO? { ● It takes a lot of bandwidth to downloadBIGa few some web pages ● Mobile devices are usually connected to high latency networks: cell towers. Not even wi-fi is as reliable as fiber optic.PROBLEMS ● You may have to do this a lot of times just for all the data needed for a single screen
  11. 11. OK…You can do all that on a web server in less than thetime* for a request from a 3G Galaxy Nexus toreach the web server.*that’s if you don’t have the data stored in a DB andyou have to fetch it from one or more sources.
  12. 12. SO, WEB SERVICES…● Just like Q & A
  13. 13. SO, WEB SERVICES…● Just like Q & A { Q: THE REQUEST
  14. 14. SO, WEB SERVICES…● Just like Q & A { Q: THE REQUEST A: THE RESPONSE
  15. 15. SO, WEB SERVICES…● Just like Q & A { Q: THE REQUEST A: THE RESPONSE● Types: REST & SOAP;
  16. 16. SOAP● REQUEST: XML, specific format;● RESPONSE: XML, specific format;
  17. 17. REST● REQUEST: HTTP or other*;● RESPONSE: XML or JSON; any type of document you like; *HTTP is the norm. But you can also have XML or JSON requests.
  18. 18. XML VS JSON● XML: human readable and compatible with most platforms;● JSON: compact and quick to parse;
  19. 19. NO DATA ON YOUR SERVER? ● Scrape it; ● Cache it and/or store it; ● Serve the data later from the local cache;
  20. 20. SIMPLE PLAN OF A PARSER ● Start point; ● Data gathering points; ● End point ; ● Regular expressions;
  21. 21. START, DATA, END
  22. 22. FEROVIAR
  23. 23. STRUCTURING DATA● Try and return only one type of object per API call● For every object type use the same schema everywhere.● In some cases you can return less data per object, but where you have more data return it in the same format
  24. 24. STRUCTURING DATA● If your objects have many-to-many relationships with other objects remove redundanciesI.e : use person_id to identify a person andat the end of the response return all theunique persons in the current call
  25. 25. STRUCTURING DATA Use pagination!
  26. 26. BUT IF YOU CAN’T…● Add an API call that tells you if the data has been changed (timestamp, hash, integer, etc)● At least make sure you compress the response
  27. 27. ANDROID SUPPORTS GZIP, DEFLATE// REQUESTHttpUriRequest request = new HttpGet(url);request.addHeader("Accept-Encoding", "gzip");// ...httpClient.execute(request);// RESPONSEInputStream instream = response.getEntity().getContent();Header contentEncoding = response.getFirstHeader("Content-Encoding");if (contentEncoding != null &&contentEncoding.getValue().equalsIgnoreCase("gzip")) { instream = new GZIPInputStream(instream);}
  28. 28. TIPS● Build an API call that returns images in the request shape & size;● Less bandwidth required, less memory used and less CPU time spent on rendering (no more stretching/shrinking, positioning and cropping);
  29. 29. TIPS● Never trust the client;● Do your security and policy checks server side also;● Secure every call with a signature: call parameters, private key, timestamp or unique call id per session ➔ hashed;
  30. 30. ANDROID SIDE OF THINGS ● Parsing JSON: JSONObject or Jackson ● Objects vs Streaming
  31. 31. ANDROID SIDE OF THINGS ● Generate objects from the data only if you need them right then; ● In some cases (loading screens) you may need to load a lot of data for later use; ● Throw lots of data straight to a SQLite DB using TRANSACTIONS
  32. 32. WHY TRANSACTIONS?● Not just a concept borrowed from traditional *SQL databases● Uses less I/O. A whole lot less I/O.● Like 100x faster than saving each data line by line
  33. 33. REDESCOPERA ROMANIA
  34. 34. SAVING● To SQLite Databases: persistent objects with later use● To static objects: volatile objects that will only be used just this session● To parcelable objects: even more volatile objects● To SharedPreferences: persistent key-value data or singleton objects
  35. 35. CACHING● Always cache to the filesystem the images you download from the web;● That’s what the ~/cache dir is for;● Limit your bitmap memory cache and make sure you also recycle the bitmaps when you clear them from the cache;
  36. 36. PLAYING NICE WITH THE WEB SERVICE Detect unique install id: generate a GUID SharedPreferences prefs = context.getDefaultSharedPreferences(); String uniqueGUID = prefs.getString("install_guid", null); if (uniqueGUID == null) { ! uniqueGUID = UUID.randomUUID().toString() ! prefs.edit().putString("install_guid", uniqueGUID).commit(); }
  37. 37. PLAYING NICE WITH THE WEB SERVICE Detect unique device id: use ANDROID_ID String deviceId = Settings.Secure.getString(contentResolver,Settings.Se cure.ANDROID_ID);
  38. 38. PLAYING NICE WITH THE WEB SERVICE● Send debugging and app identification data in HTTP header● App Name/Version● Device manufacturer/Model/ID Helps debugging issues remotely and Allows web admins to control access to their web service
  39. 39. THANKSemail: auras@wip.rotwitter: @aurasThis presentation is available at:http://wip.ro/droidcon/auras.pdf

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