1. Blogs & feeds Jim des Rivieres Oct. 16, 2008

2. Grappling with question of how to present Jazz/OSLC data resources “Pure” data resources are presentation- free Okay for programmatic clients - robots But how do they get presented to humans???

3. Blogs and Atom/RSS feeds –Has similar issues Ask: How do blogs and feeds work? Mine for ideas on how to solve for Jazz

4. Blogs are hosted at web sites

5. Native blog page is text/html Page generated by blogging web site

6. Page has blog entries embedded in it

7. Browsers have hard-wired support for feeds (Atom and RSS) Each blog has an associated feed

8. Browser discovers feed links from special elements in HTML header

9. Browser presents feeds using hard-wired feed view

10. Feed is XML document - application/atom+xml Generated by blogging web site

11. Feed has blog entries embedded in it

12. Browser recognizes feed by inspecting XML –Looks for as root document element –Looks for Atom XML namespace Browser ignores Content-Type response header –Works if document is text/plain

13. Browsers feed view allows navigation to blog

14. Browser discovers this from special element in feed header

15. Subscribe to feed pops up browser dialog to add to browser favorites

16. Feed entries may contain other info that is not presented by browser feed view… –Comments on entries is not an Atom concept

17. …but do show up in native blog view –Comments on entries is known to blog site

18. Feed entries may also contain info that is presented by neither native blog page nor browser feed view

19. Feed entries have their own URLs

20. Feed entries have links back to native blog entry

21. Feed document sometimes carry XML stylesheets –Used to make XML document directly renderable by browsers –Browser applies XML stylesheet (CSS, XSL) to XML document Ignored by hard-wired browser feed view

22. XML feed rendered with XML stylesheet (simulated)

23. Different XSL style sheet

24. XML feed rendered with XML stylesheet (simulated)

25. Feed aggregation

26. Aggregation sites collect entries from various feeds Presents entries through its own native view

27. Links in aggregated blog entries refer to original blog entry

28. Allowing navigation back to native blog page

29. Aggregation site also publishes its own feed

30. Which is viewable with browser feed view (like any other feed)

31. Links in feed entries refer to original blog entry

32. Allowing navigation back to native blog page

33. Recap – Story so far User does not choose presentation of blog entry Choice of presentation is determined by how user gets to blog entry

34. Feed readers Give users (as opposed to authors) a way to aggregate entries from diverse feeds Two main types –Web-based –Desktop tool

35. Web-based feed readers Nothing extra installed on client machine –Not even browser plug-in/add-in All preferences/state maintained on remote web server

36. Web-based feed readers

37. Allow you to…

38. …to discover feeds

39. …and to subscribe to them

40. New entries are presented in web feed reader Disappear from sight once read

41. Some links in blog entries refer to original blog entry

42. Allowing navigation back to native blog page

43. Some links in blog entries are within the web feed reader

44. Allowing in-place browsing of feeds that you’ve subscribed to

45. Adding subscription from feed URL Who reads feed document? Browser? Web feed reader server?

46. Browser talks to web feed reader server exclusively Browser POSTs subscribe request to reader server API Reader server retrieves and processes feed Browser GETs list of unread items via reader server API

47. Desktop feed readers Desktop app installed on client machine Preferences/state maintained on client –Sometimes on remote server (optionally)

48. Desktop feed readers

49. Let you subscribe to feeds

50. New entries are presented in feed reader Disappear from sight once read

51. Some links in blog entries refer to original blog entry

52. Allowing navigation back to native blog page Opened in-place with browser widget

53. Feedburner

54. Some blogs use feedburner

55. Navigation from blog entry…

56. …redirects to feed view on feedburner.com

57. Lets you subscribe with popular web feed readers

58. Hyperlinks go to web feed reader server –Pass feed URL as parameter

59. Also lets you subscribe with popular desktop feed readers

60. As well as navigate to feed document

61. Hyperlink to feed XML

62. For viewing in browser feed view

63. Recap Blogs and blog entries have URLs Presentation level - HTML document http://inside-swt.blogspot.com/ http://planet-oti.muellerware.org/ Feeds and feed entries have URLs Data level - XML document http://inside-swt.blogspot.com/feeds/posts/default http://planet-oti.muellerware.org/atom.xml Rich cross-linking –Within levels –Across levels

64. Recap Each feed/entry resource has a native web presentation

65. Recap Use special elements embedded in feed resource Uses special elements embedded in HTML resource Does not use content negotiation –(except for a few anomalies with feedburner)

66. Recap Story relies in places on browser built-in feed view –Allows direct hyperlinking from presentation to data level –Allows feed URL to be typed in to browser

67. Recap Many, many presentations for a blog entry –Native presentation at originating blog –Each browser feed view Slightly different for each browser –Native presentation at each aggregation site –Web-based feed readers –Desktop feed readers

68. Recap User does not choose presentation of blog entry Choice of presentation is determined by how user gets to blog entry User is free to choose which feed reader to use –Optional

69. Thanks Fiddler Web Debugging Proxy –Free Microsoft tool for Windows –Lets you inspect HTTP traffic that IE sends –Approved for individual IBM-internal use –http://www.fiddler2.com/fiddler2/http://www.fiddler2.com/fiddler2/