OSGi on Google Android using Apache Felix
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The document presents a comprehensive overview of implementing OSGi (Open Service Gateway Initiative) on Google Android using Apache Felix. It discusses Android's architecture, the OSGi framework, dynamic application development, and specific components like activities and services. Additionally, it contains insights into the history of OSGi, its alliance, and practical information about building secure OSGi applications on Android.
OSGi on Google Android using Apache Felix
- 1. OSGi on Google Android using Apache Felix Marcel Offermans Karl Pauls luminis
- 2. luminis Who are we? • Karl Pauls • Marcel Offermans Arnhem Enschede image © 2008 Google Earth
- 3. luminis Agenda • Android • Introduction and architecture • Hello world demo • OSGi • Introduction • Framework and compendium • Apache Felix on Google Android • Getting it to run • Creating a dynamic application: paint program
- 4. luminis Agenda • Android • Introduction and architecture • Hello world demo • OSGi • Introduction • Framework and compendium • Apache Felix on Google Android • Getting it to run • Creating a dynamic application: paint program
- 5. luminis Android • First SDK release: november 2007 • Android Developer Challenge, $10M prize money • Current SDK (M5 RC15): march 2008 • Phones: second half of 2008?
- 6. luminis Android • Device Architecture • Dalvik Virtual Machine • From source to deployment • Anatomy of an application • Application life cycles
- 7. Architecture This image is rather low-res, so perhaps draw it again... luminis
- 8. luminis Dalvik Virtual Machine • interpreter-only, register based virtual machine • optimized to run multiple VM instances • executes files in .dex format • runs on posix-compliant operating systems • looks like Java ;)
- 9. From source to deployment .java .class .jar .dex .apk • Eclipse Plugin: Android Development Tools • compiles and packages automatically • allows you to launch and debug in the emulator • Command line: activityCreator.py • generates project structure • Ant build.xml file, optionally IntelliJ project files luminis javac jar dx aapt
- 10. luminis Anatomy • activity, a single screen • intent, describes what the application wants done • intent filter, describes intents that can be handled • intent receiver, non UI code that reacts to intent • service, background process with API • content provider, for shared data access
- 11. luminis Anatomy Example intent filter activity intent activity intent service intent filter intent receiver
- 12. luminis Life cycle • Application life cycle is not controlled by the application itself • Android maintains an “importancy hierarchy” based on the components and their state: • foreground process • visible process • service process • background process • empty process
- 13. luminis Life cycle (Activity)
- 14. luminis Hello world demo! • Create an application with an activity in Eclipse • Set “hello world” text • Create a breakpoint • Deploy and debug the application
- 15. luminis Agenda • Android • Introduction and architecture • Hello world demo • OSGi • Introduction • Framework and compendium • Apache Felix on Google Android • Getting it to run • Creating a dynamic application: paint program
- 16. luminis OSGi history • Started as an embedded platform for the “home gateway” • Originally under the JCP as JSR-8 (1999) • OSGi alliance, consists of a large number of big companies, with the following mission: • Maintaining and publicizing the OSGi specification. • Certifying implementations. • Organising events. • Current version: OSGi Release 4.1 (JSR-291)
- 17. luminis OSGi today OSGi technology is the dynamic module system for Java™ OSGi technology is Universal Middleware. OSGi technology provides a service-oriented, component-based environment for developers and offers standardized ways to manage the software lifecycle. These capabilities greatly increase the value of a wide range of computers and devices that use the Java™ platform.
- 18. luminis OSGi Alliance • Expert Groups: • core platform (CPEG) • mobile (MEG) • vehicle (VEG) • enterprise (EEG) • residential (REG) • Working Groups: • marketing • requirements
- 19. luminis OSGi specification OSGi Service Platform Service Compendium The OSGi Alliance Release 4, Version 4.1 April 2007 OSGi Alliance Digitally signed by OSGi Alliance DN: cn=OSGi Alliance, c=US Date: 2007.02.22 14:44:10 + 01'00' Signatu re Not Verified OSGi Service Platform Core Specification The OSGi Alliance Release 4, Version 4.1 April 2007 OSGi Alliance Digitally signed by OSGi Alliance DN: cn=OSGi Alliance, c=US Date: 2007.02.22 14:45:47 + 01'00' Signatur e Not Verified
- 20. OSGi Framework Layering luminis SERVICE MODEL LIFECYCLE MODULE Execution Environment L3 - Provides a publish/find/bind service model to decouple bundles L2 - Manages the life cycle of a bundle in a framework without requiring the vm to be restarted L1 - Creates the concept of a module (aka. bundles) that use classes from each other in a controlled way according to system and bundle constraints L0 - OSGi Minimum Execution Environment CDC/Foundation JavaSE
- 21. Bundle luminis Module Layer (1/3) • Unit of deployment is the bundle i.e., a JAR • Separate class loader per bundle • Class loader graph • Independent namespaces • Class sharing at the Java package level Module Module Bundle Bundle Bundle org.apache.utils 1.0 exports org.apache.db 1.4 org.apache.log 2.3 org.apache.utils 1.1 exports imports exports imports exports
- 22. luminis Module Layer (2/3) • Multi-version support • i.e., side-by-side versions • Explicit code boundaries and dependencies • i.e., package imports and exports • Support for various sharing policies • i.e., arbitrary version range support • Arbitrary export/import attributes • Influence package selection Module
- 23. luminis Module Layer (3/3) • Sophisticated class space consistency model • Ensures code constraints are not violated • Package filtering for fine-grained class visibility • Exporters may include/exclude specific classes from exported package • Bundle fragments • A single logical module in multiple physical bundles • Bundle dependencies • Allows for tight coupling when required Module
- 24. Life-cycle resolved active luminis Life-cycle Layer • Managed life cycle • States for each bundle; • Allows updates of existing bundles. • Dynamically install, start, update, and uninstall Life-cycle start end installed install start starting stopping stop uninstall uninstalled Module
- 25. luminis Service Layer • OSGi framework promotes service oriented interaction pattern among bundles Service Service Log Database publish use use publish Bundle Bundle Bundle Bundle Prefs publish use publish find Service Provider Service Requester Service Registry interact Life-cycle Module
- 26. Service Life-cycle luminis Security • Optional Security Layer based on Java permissions • Infrastructure to define, deploy, and manage fine-grained application permissions • Code authenticated by location or signer • Well defined API to manage permissions • PermissionAdmin • ConditionalPermissionAdmin Security Module
- 27. luminis Shameless plug: if you want to know more about security in OSGi, come to our talk about Building Secure OSGi Applications
- 28. Leveraging standard services • Specification: • OSGi compendium – catalog of standard service luminis descriptions • Implementations: • OBR repository at bundles.osgi.org – over 1400 bundles, implement compendium and other services • Maven repository and third party OBR’s • More and more projects are made OSGi compatible, for example: • Apache Commons OSGi
- 29. User Admin Wire Admin luminis OSGi compendium Log XML Parser Position Measurement and State Event Admin Service Tracker HTTP Device Access Configuration Admin Preferences Metatype IO Connector Initial Provisioning UPnP™ Device Execution Environment Spec Declarative Services OSGi Service Platform Service Compendium The OSGi Alliance Release 4, Version 4.1 April 2007 OSGi Alliance Digitally signed by OSGi Alliance DN: cn=OSGi Alliance, c=US Date: 2007.02.22 14:44:10 + 01'00' Signatu re Not Verified
- 30. luminis Agenda • Android • Introduction and architecture • Hello world demo • OSGi • Introduction • Framework and compendium • Apache Felix on Google Android • Getting it to run • Creating a dynamic application: paint program
- 31. luminis Why OSGi and Android? Models are different Java VM App OSGi Dalvik VM App App App Dalvik VM App Dalvik VM App Android
- 32. luminis Benefits of each model Java VM invoke App App Java VM App App lib lib lib Dalvik VM App OSGi Android Dalvik VM App Dalvik VM App crash
- 33. Services in Android • Must be declared in AndroidManifest.xml • Can be started and stopped: Context.startService and Context.stopService() • You can bind to a service if you want to talk to it • Services can run in remote processes, in which case there is an Android IDL compiler to generate stubs • handles primitives, some collections and Parcelable’s luminis by value • handles other AIDL interfaces by reference
- 34. luminis Getting Felix to run... • First step, getting the framework to run • Apache Felix is very portable, so we just dex’ed it • found a couple of issues, fixed in release 1.0.3 • Second step, dynamically loading bundles • the hard part was finding a way to load classes • found undocumented internal class • Google, we need an official API for this! • For more details: http://blog.luminis.nl/roller/luminis/entry/osgi_on_google_android_using
- 35. ...others soon followed • At EclipseCon 2008, Santa Clara: • Neil Bartlett and BJ Hargrave, ported both Equinox and luminis Concierge to Android • Slides at: https://eclipsecon.greenmeetingsystems.com/attachments/download/390 • ProSyst announced: • A port of their mBedded Server: http://www.adon-line.de/kunden/prosystBlog/?p=24 • Knopflerfish • We talked to Eric Wistrand and Christer Larsson of MakeWave but they have no plans yet
- 36. luminis A dynamic application • Apache Felix framework • embeds an activity to hook into; • embeds file install bundle for easy deployment. • Host bundle that provides a canvas and a toolbar • Shape bundles that add new shapes • Based on example from Apache Felix website: http://felix.apache.org/site/apache-felix-application-demonstration.html
- 37. host bundle ShapeComponent getShape() : SimpleShape getX() : int getY() : int DefaultShape create(Context c) : View Activator shape bundle shape bundle luminis Architecture shape bundle apache felix application ...osgi... ...android... Activity ... ...android.felix ApacheFelix onCreate(Bundle b) onDestroy() onStart() onStop() ...android.felix.view ViewFactory create(Context c) : View ...android.servicebased.host ... ...android.servicebased.host.service SimpleShape draw(Canvas c, int x, int y) BundleActivator start(BundleContext c) stop(BundleContext c) ServiceTrackerCustomizer addingService(ServiceReference r) : o modifiedService(ServiceReference r, Object o) removedService(ServiceReference r, Object o) ...android.servicebased.circle Activator ...
- 38. luminis Live demo! • Deploying Felix to the Phone Emulator • Installing the first bundle, the host application • Adding and removing plugins: square, circle and triangle
- 39. luminis Links • Slides, docs and code: http://opensource.luminis.net/ • Android SDK: http://code.google.com/android/ • Open Handset Alliance: http://www.openhandsetalliance.com/ • Apache Felix and OSGi: http://felix.apache.org/ http://www.osgi.org/ • Karl Pauls: karl.pauls@luminis.nl Marcel Offermans: marcel.offermans@luminis.nl
- 40. luminis Questions?! ? & !