Cross-app communication and plugin architecture in Android

A presentation by Siebe Sysmans.
This presentation was given for Mobel (http://www.mobel.io) and IT students.
Code: https://github.com/appfoundry/AndroidPluginArchitecture

Transcript

1. Android Plugin Architecture
2. Cross-app communication
3. Cross-app communication • Intent and BroadcastReceiver • ContentResolver and ContentProvider • Services
 …
4. Android Plugin Architecture
5. Android Plugin Architecture • Why? • User Plugin Discovery • Host App Plugin Discovery • Plugin Communication
6. App Examples
7. DashClock Widget
8. DashClock Widget
9. Muzei Live Wallpaper
10. Muzei Live Wallpaper
11. Why?
12. Ecosystem-based marketing • Don’t create all your own plugins • Open up an API to extend your app • Indirectly promoting your app
13. Business Model • Free app with basic functionality • Paid plugins
14. Permission Mitigation • Standard Android is all or nothing • People might not install your permission rich app • Provide core app with less permissions • User can choose permissions by installing plugins (Before Android 6)
15. User Plugin Discovery
16. User Plugin Discovery • Hardcode references in core app • Link to a search term on Play Store • Download a JSON • Use a WebView • …
17. App Plugin Discovery
18. BroadcastReceiver Host app Plugin app BroadcastReceiver BroadcastReceiver Are there any plugins? Plugin app BroadcastReceiver
19. BroadcastReceiver Host app Plugin app BroadcastReceiver BroadcastReceiver Yea, I’m a plugin! Plugin app BroadcastReceiver Yea, I’m a plugin!
20. BroadcastReceiver • Not recommended • It wakes up every plugin app • Not sure when every plugin app responded
21. PackageManager • Every plugin implements a custom intent action • PackageManager queries for every component using that custom action • Easily get metadata of that component
22. Package Broadcasts • Android system sends package broadcasts • Host app checks if we are interested
 in that package change • Host app can update a live list of plugins
23. Package Broadcasts Host app BroadcastReceiver ListView Android System App installs App replaces App deletes
24. Package Broadcasts Host app BroadcastReceiver ListView Android System App installs App replaces App deletes PACKAGE_ADDED
 PACKAGE_REPLACED PACKAGE_REMOVED
25. Package Broadcasts Host app ListView Android System App installs App replaces App deletes PACKAGE_ADDED
 PACKAGE_REPLACED PACKAGE_REMOVED Update
26. Plugin Communication
27. MetaData Great for getting static data • Plugin name • Plugin icon • Plugin api level
28. Coding Example MetaData Using resources from other app PackageManager manager = getPackageManager(); Resources pluginResources = manager.getResourcesForApplication("com.example.pluginapp"); int drawableResID = pluginResources.getIdentifier("app_icon", "drawable", "com.example.pluginapp"); Drawable drawable = pluginResources.getDrawable(drawableResID);
29. BroadcastReceiver Host app Plugin app BroadcastReceiver BroadcastReceiver Provide me data
30. BroadcastReceiver Host app Plugin app BroadcastReceiver BroadcastReceiver Here’s my data
31. Remote Service Binding • Preferred way • Remote services found with PackageManager • Communication protocol using AIDL • Callback with Messenger for delayed responses
32. Remote Service Binding - AIDL • All primitive types • int • long • char • … • String • Charsequence • List (ArrayList) • Map (HashMap) • Parcelable
33. Remote Service Binding Host app Plugin app AIDL Compile Stub Stub Build
34. Remote Service Binding Host app Plugin app Stub Stub Impl Impl Build
35. Remote Service Binding Host app Plugin app Stub Stub Impl Impl Bind Run
36. Remote Service Binding Host app Plugin app Stub Stub Impl Impl IPC Run
37. GUI Plugins
38. WebViews • Plugin provides data • Static URI using MetaData • Dynamic URI using IPC • Host has a WebView that loads the data • Easy • Not native • Security issues (javascript)
39. RemoteViews • Native • Homescreen widgets • Lockscreen widgets • Notifications • Only basic View Widgets • Parcelable!
40. Roll Your Own Parcelable • More flexible • A lot more work • Need to version your view building
41. Some extra tips
42. Some Extra Tips • Think about your versioning • Abstract to a library for distribution • Input validation in host • Make sure it’s secure • Don’t leak data
 →using signature level permissions
43. Questions? Siebe Sysmans Consultant at AppFoundry siebe.sysmans@appfoundry.be @ThisIsSiebe