1. Slide 1 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Using OSGi to Build Better Software Lessons from a Telemedicine Software for Smartphones and Desktop Systems Doreen Seider (DLR - German Aerospace Center) ApacheCon NA 2011 (Vancouver, 11/11/2011)

2. Slide 2 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Outline What software did we want to have? How did we develop it with OSGi? What did we learn?

3. Slide 3 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011

4. What kind of software did we want to have? ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Slide 4

5. Slide 5 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Telemonitoring Software Supports remote monitoring of patients (e.g. in rural areas) Captures vital sign of patients from medical devices Sends measurements to doctors sitting in a medical service center Executable on mobile devices and desktop systems Supports any kind of medical device and medical service center

6. Slide 6 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Already Exist: Unflexible Telemonitoring Software

7. Slide 7 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Unflexible Telemonitoring Software Technologies

8. Slide 8 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 In Comparison to That: Flexible Telemonitoring Software

9. Slide 9 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Flexible Telemonitoring Software Technology Plug&Care Connector

10. Slide 10 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Plug&Care Connector Requirements 1. Both on smartphones (like Android or Windows Mobile) and on desktop system executable 2. Support of any device and service center – even later on – without modification of the Plug&Care Connector

11. How did we develop it with OSGi? ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Slide 11

12. Slide 12 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Plug&Care Connector‘s Architecture

13. Slide 13 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Bundles and Services OSGi is specification of a modular service platform written in Java „modular“ It is a module layer above the Java package layer Classes are assembled to packages  packages are assembled to bundles (modules)  bundles are assembled to applications

14. Slide 14 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Bundles and Services By default bundles are totally encapsulated Bundles can make use of each other by explicit exports and imports of packages

15. Slide 15 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Bundles and Services OSGi is specification of a modular service platform written in Java „service“ In a perfect world bundles make use of each other via services Eliminates direct dependencies to each others implementation

16. Slide 16 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Bundles and Services

17. Slide 17 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Bundles and Services Service definition and implementation are separated to each other No direct implementation dependencies Enables loose coupling Important for assembling bundles (jars) to applications

18. Slide 18 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Bundles and Services

19. Slide 19 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Declarative Services (DS) OSGi Runtime calls the bundle and not other way around

20. Slide 20 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Declarative Services (DS) Bundles provide a set of so called component descriptions A component is a Java class Each describes which services a component provides and consumes OSGi runtime injects all required services at start up

21. Slide 21 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi Principles: Declarative Services (DS) Benefits of Declarative Services Less complexity in own code Better testing (no mock up of OSGi runtime needed)

22. Slide 22 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Fulfilling Requirements with the help of OSGi 1. Both on smartphones (like Android or Windows Mobile) and on desktop system executable Platform independency by realizating it as OSGi application OSGi serves as an abstraction layer of underlying diversity Using different implementations of OSGi for different platforms Assembling bundles to the Plug&Care Connector application according to its deployment platform

23. Slide 23 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Used OSGi Implementations: Equinox For desktop Eclipse Software Foundation OSGi implementation under Eclipse Decision was made due to experiences from other software we develop

24. Slide 24 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Used OSGi Implementations: mBS Mobile For Smartphones ProSyst company (http://prosyst.com)http://prosyst.com Android, Windows Mobile, Nokia S60 http://dz.prosyst.com/mbsmobile/ Decision was made due to supported platforms at that time and due to development status

25. Slide 25 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Used OSGi Implementations: mBS Mobile Integration in Android

26. Slide 26 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Used OSGi Implementations: mBS Mobile OSGi Management on Android

27. Slide 27 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Used OSGi Implementations: mBS Mobile OSGi Applications on Android

28. Slide 28 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi-Stack: mBS Mobile Development Environment in Eclipse

29. Slide 29 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 OSGi-Stack: mBS Mobile Development Environment in Eclipse

30. Slide 30 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Abstraction with the use of Console OSGi comes with a console for management purposes It is useful for testing i.e. interacting with the application if no GUI is available yet Own commands can be provided Different OSGi implementations might have different console APIs Abstraction of console APIs is needed to hide them for the underlying application layers writing to the console

31. Slide 31 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Abstraction with the use of Console Layered architecture of affected bundles

32. Slide 32 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Abstraction with the use of Device Communication Measurements are captured via Bluetooth There are different bluetooth implementations on different devices Later on not only Bluetooth, but USB should be supported as well Abstraction of communication layer and Bluetooth implementations is needed to ensure driver implemenentation must not be changed

33. Slide 33 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Abstraction with the use of Device Communication Layered architecture of affected bundles

34. Slide 34 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Abstraction with the use of Console and Device Communication Deployment

35. Slide 35 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Fulfilling Requirements with the help of OSGi 1. Both on smartphones (like Android or Windows Mobile) and on desktop system executable Platform independency by realizating it as OSGi application OSGi serves as an abstraction layer of underlying diversity Using different implementations for different platforms 2. Support of any device and service center – even later on – without modification of the Plug&Care Connector Establish plugin concept Get plugins with help of modularity of OSGi Handle plugins (registration) by the use of dependency injection provided by OSGi (Declarative Services)

36. Slide 36 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Driver and Transmitter Plugins and its Registration Requirements Self-sufficient deployment OSGi as transparent as possible to thrid party developer Use as much OSGi as possible to reduce own amount of code

37. Slide 37 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Plugin and Registry Concept using the Example of Driver How did we realize it?

38. Slide 38 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Plugin and Registry Concept using the Example of Driver

39. Slide 39 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Plugin and Registry Concept using the Example of Driver What does a driver developer need to do? Implement the driver interfaces provided by Plug&Care Connector Provide a component description like that:

40. Slide 40 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Plugin and Registry Concept using the Example of Driver What does the Plug&Care Connecor do? Provides component description like that: <component name=„Driver Registry„ <reference name="de.pncc.driver„ interface="de.pncc.drivers.Driver„ bind="addDriver„ unbind="removeDriver Implements bind and unbind method to e.g., store the driver in a list

41. Slide 41 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Plugin and Registry Concept using the Example of Driver What does OSGi do? Everything else like listen to new driver bundles, retrieving there provided driver services, inject them to the right place, handles uninstalled driver bundles, …

42. Slide 42 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Plugin and Registry Concept using the Example of Driver In a nutshell: Driver installation

43. Slide 43 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Designing Plug&Care Connector Plugin and Registry Concept using the Example of Driver In a nutshell: Driver deinstallation

44. What did we learn? ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Slide 44

45. Slide 45 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 What did We Learn? Living out OSGi principles is a good base for building better software (in terms of maintance and deployment).

46. Slide 46 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Living out OSGi Principles Services Use services Seperate service interface and service implementation Allows abstraction and loose coupling Makes application More robust against changes Deployable in different environments just by assempling different kind of jar files

47. Slide 47 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Living out OSGi Principles Declarative Services Prerequisite is usage of services Make use of dependency injection Let other maintain the code for dependency handling Get your code free from OSGi API Makes application Easier to test by injecting stub or mock objects More robust because fewer lines of code (every reduced line of code, reduces the chance for a bug) Easier to understand and use by third party developers knowing nothing about OSGi

48. Slide 48 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011 Living out OSGi Principles Encapsulation Make only those code public which is really intended to be public Hide as much as possible from the outer world In perfect word only the (service) interfaces are public Makes application More robust against changes because third party code can only be depend on a little part of your applications‘s implementation Architecture smarter, because you need to think about it in more detail

49. Slide 49 ApacheCon 2011 > Doreen Seider> Using OSGi to Build Better Software > 11.11.2011