- webOS offers multi-window apps but this presents complications as the web is not designed for this behavior. There are performance issues and reliance on globals like document and window. - There are different types of stages including cards, dashboards, and popups. Dashboards and popups introduce new interactions that require refactoring assistants to be more generic. - Relaunching is when certain actions cause an app to be relaunched, passing arguments to the appManager service. The AppAssistant handles relaunching and shared state across child stages. Upcoming API improvements will make default dashboards and singletons easier to implement.

2. Advanced webOS
Justin Tulloss
Sr. Software Engineer
April 24, 2010

3. Overview
• Multi-Stage basics
• Dashboards
• Popups
• Relaunching
• The Future
• Q&A

4. Why Is This So Complicated?
The web isn’t designed for multi-window apps
• Big departure from normal browser behavior
• webOS offers a lot of different interactions
• Performance issues led to complications
• Expected globals (document, window, etc.)
• Late recognition of the problem by Palm. Sorry.

5. Multi-Stage Basics

6. Things to Consider
• Do you need another stage? Every time?
• What is the most appropriate stage type?
• How often do you rely on globals?
• Prototype, jquery, document?
• What state is shared between children?

7. Basic APIs

8. From a Scene Assistant

9. Stage Types
• Card
• Dashboard
• Popup

10. Dashboards
and Banners

11. Example: MainAssistant

12. Example: DashboardStageAssistant

13. Example: Message View

14. Example: MessageAssistant

15. Popups

16. Some New Twists
• Refactor child stage assistant to be generic
• Not all stylesheets are loaded
• Some styles are changed to assume a notification
• Popups can have their height specified
• Closing child windows is easy

17. Example: New ChildStageAssistant

18. Example: Pushing Dashboard Scene
Moved

19. Example: Creating a Popup

20. Example: Popup Scene

21. Example: Popup Assistant

22. Example: Very Simple Popup

23. Relaunching

24. Relaunching Basics
• Certain actions cause your app to be “relaunched”
• The appManager service passes in arguments
• Your AppAssistant can change default launch
behavior
• You should never have to worry about whether or
not your app was already open

25. AppAssistant
• Shared across all child stages
• Handles relaunching
• Convenient place to stick shared state
• Try not to share state

26. Example: App Assistant

27. Example: Setting Default Stage

28. Example: Launch Parameters in
Banner

29. The Future

30. Upcoming API Improvements
• Default dashboards no longer require markup
boilerplate
• Just provide an icon, some text, and a count
• Handles going from single item to multiple
• SingletonStages
• No more stageProxy shenanigans
• Failure cases are handled more elegantly

31. Q &A