An overview of various private experiments to implement Linked Data using Ontopia.

1. Experiments in linked data Lars Marius Garshol, <larsga@bouvet.no> Topic Maps 2010, Oslo, 2010-04-15 http://twitter.com/larsga

2. What is this talk about? Connecting across applications using common identifiers for subjects The applications are tmphoto photo gallery tmtools Topic Maps tools index Larsblog my private blog tmcase1 Naito-san’s index of Topic Maps talks ontopia.net the new Ontopia web site (not live yet)

3. Why experiments? I prefer to talk about real projects but linked data has been hard to sell to customers because the concept is hard to grasp? because collaboration between organizations is hard? because the market wasn’t ready yet? anyway, there are very few projects so far Therefore I’m showing some private experiments instead the scale and complexity are limited but it does demonstrate some of the potential

4. A lightning tutorial Identifiers

5. Identifiers? PSIs (Published Subject Identifiers) a part of the Topic Maps standard, used for merging a URI attached to a topic to identify it the URI should refer to a page defining the subject T http://psi.ontopedia.net/Lars_Marius_Garshol

6. Name Definition

7. PSIs – things to note Anyone can make a PSI as long as they can publish content on the web Domain names ensure PSIs are globally unique only I make PSIs starting http://psi.garshol.priv.no/ PSIs can identify anything if you can imagine it, you can make a PSI for it

8. Starting with the first application So, to the experiments

9. tmphoto Category Person Photo Event Location http://www.garshol.priv.no/tmphoto/ A topic map to organize my personal photos contains ~15,000 photos A web gallery runs on Ontopia on www.garshol.priv.no

10. You need more than one application to have true linked data. Data inside a single application is of course linked, but only in a trivial sense. No linked data at this point

11. tmtools http://www.garshol.priv.no/tmtools/ Organization An index of Topic Maps tools organized as shown on the right Again, web application for browsing screenshots below Person Software product Platform Category Technology

12. The person page Boring! No content.

13. And in tmphoto...

14. get-illustration A web service in tmphoto receives the PSI of a person then automatically picks a suitable photo of that person Based on vote score for photos, categories (portrait), other people in photo ... The service returns a topic map fragment with links to the person page and a few different sizes of the selected photo http://www.garshol.priv.no/blog/183.html

15. get-illustration Hmmm. Scores, categories, people in photo, ... Do you have a photo of http://psi.ontopedia.net/Benjamin_Bock ? http://www.garshol.priv.no/tmphoto/get-illustration?identifier=http://psi.on.... tmphoto tmtools Topic map fragment

16. Voila...

17. Points to note No hard-wiring of links just add identifiers when creating people topics photos appear automatically if a better photo is added later, it’s replaced automatically No copying of data no duplication, no extra maintenance Very loose binding nothing application-specific Highly extensible once the identifiers are in place we can easily pull in more content from other sources

18. How to choose common identifiers? I was of course able to use the same PSI because I produced both datasets But what if the two applications were maintained by different people? Subj3ct.com solves that problem search on Subj3ct to find global identifiers for your subjects

20. Overview tmtools tmphoto get-illustration

21. Now what? So far, so good

22. My blog Has more content about people (tmphoto & tmtools), events (tmphoto), tools (tmtools), technologies (tmtools) Should be available in those applications

23. Solution My blog posts are tagged but the tags are topics, which can have PSIs these PSIs are used in tmphoto and tmtools, too The get-topic-page request lets tmphoto & tmtools ask the blog for links to relevant posts given identifiers for a topic, returns links to pages about that topic http://www.garshol.priv.no/blog/145.html

24. get-topic-page Do you have pages about http://psi.ontopedia.net/TMRA_2008 ? http://www.garshol.priv.no/blog/get-topic-page?identifier=http://psi.on.... Blog tmphoto Topic map fragment Topics linking to individual blog posts

25. In tmphoto

26. Overview tmtools tmphoto get-illustration get-topic-page blog

27. Easy next steps Topic pages on the blog must link to tmtools and tmphoto trivial to do via get-topic-page And the blog can use get-illustration, too and so can ontopia.net and tmcase1 Oh, and they should link to the blog and the other applications...

28. After a little hacking... What a mess! tmcase1 tmtools tmphoto ontopia.net blog get-topic-page get-illustration

29. We need a clean-up here The get-topic-page service is generic that is, it’s not tied to any specific application further, the result set is a topic map fragment Topic maps can be merged as we know So, we could make a hub service basically, a get-topic-page aggregator

30. Client app #2 Client app #1 Client app #3 How it works Hub service blog tmcase1 tmtools tmphoto ontopia.net

31. Benefits of this approach Much cleaner architecture overview diagram no longer looks like a bowl of spaghetti Easier to maintain if I want to add/remove a service I do it in a single place Safer the hub service insulates clients from slow/unresponsive servers

32. The result

33. Subj3ct.com Subj3ct is not just a database of PSIs it also has links to pages with more information about the subjects this can easily be wrapped in a get-topic-page service http://api.subj3ct.com/ subjects get-topic-page Subj3ct Wrapper service Client

34. So we can add Subj3ct... Client app #2 Client app #1 Client app #3 Hub service blog tmcase1 tmtools tmphoto ontopia.net Subj3ct

35. There is much more to tell Unfortunately, 35 minutes is not very much and this stuff takes some explaining So I had to omit sharing data with TMSync manual reuse of data with the Ontopoly editor ... Maybe next year

36. Conclusion Linked data is technically easy conceptually and politically it’s harder All you really need is shared PSIs on your topics, and someone to connect with Subj3ct.com is crucial ensures that different players pick the same PSIs independently without this there is no connecting...