Justin Tulloss discusses advanced concepts in webOS, including multi-stage apps, banners, and dashboards.

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

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. Dashboard
s and

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. Relaunchin
g

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