1. Tobias Weigel (DKRZ) Tobias Weigel Deutsches Klimarechenzentrum (DKRZ) Persistent Identifiers Solving a number of problems through a simplistic mechanism

2. Tobias Weigel (DKRZ)  What are Persistent Identifiers (PIDs)?  Extended PIDs  How to use them Agenda

3. Tobias Weigel (DKRZ) What are PIDs? 3

4. Tobias Weigel (DKRZ)  10876/abc123  10.1594/WDCC/CMIP5.NCCNMpc  ark:/13030/tf5p30086k  http://purl.org/dc/elements/1.1 /  urn:lsid:ubio.org:namebank:1181 5 4 Persistent identifiers come in various formats

5. Tobias Weigel (DKRZ) 5 Why do we need PIDs? Tracking IDCIM IDDRS Syntax...

6. Tobias Weigel (DKRZ) 6 PIDs point to resources 1010 1010 1010 101 10876/abc123 Resolution service http:// example.com/xyz567

7. Tobias Weigel (DKRZ) 7 The resource is a black box 1010 1010 1010 101 Data Metadata Software code Document ? ? ?

8. Tobias Weigel (DKRZ) 8 PIDs are globally unique 1010 1010 1010 101 10876/abc123 1010 1010 1010 101 10876/abc123

9. Tobias Weigel (DKRZ) 9 URLs are not persistent over time („link rot“) 1010 1010 1010 101 http://example.com 1010 1010 1010 101 http://example.com Today20152020 http://example.com 404 Not found

10. Tobias Weigel (DKRZ) 10 PIDs are persistent over time 1010 1010 1010 101 10876/abc123 1010 1010 1010 101 10876/abc123 1010 1010 1010 101 10876/abc123 Today20152020

11. Tobias Weigel (DKRZ) PIDs establish a redirection layer 1010 1010 1010 101 10876/abc123 http://... Stable Unstable

12. Tobias Weigel (DKRZ)  Create PID  Update the URL the PID points to  (Delete PID) 12 Operations on a PID

13. Tobias Weigel (DKRZ)  Handle System  Archival Resource Key (ARK)  Life Science Identifier (LSID)  Persistent URL (PURL)  Uniform Resource Name (URN) ... 13 There are many PID systems / infrastructures

14. Tobias Weigel (DKRZ) 14 How do PID infrastructures differ? Identifier name schema Resolver service Persistency mechanism Additional services PID Infrastructure

15. Tobias Weigel (DKRZ) We need to go beyond the simple redirection view Extended PIDs 15

16. Tobias Weigel (DKRZ) 16 Some information must be stored persistently 1010 1010 1010 101 Checksum: 7D01E436 10876/A 1010 1010 1110 101 Today 10876/A 2015 Checksum: 7D01E436 Verify... !

17. Tobias Weigel (DKRZ) 17 Build more complex information structures [1, 5, 13, 9, 12] A: 1 B: 4 C: 3 D: 7

18. Tobias Weigel (DKRZ) 18 Collections of PIDs are required for our use cases 10876/B 10876/A 10876/collectio n1

19. Tobias Weigel (DKRZ) 19 Graphs or trees of PIDs are required as well 10876/A 10876/C10876/B

20. Tobias Weigel (DKRZ) 20 The graph nodes and edges may be typed 10876/A 10876/C10876/B has metadata older versionhas metadata Data objectMetadata object Data Object

21. Tobias Weigel (DKRZ) 21 The graph structure must be stored persistently 10876/C10876/B has metadata Data objectMetadata object One combined entity 1010 1010 1010 101

22. Tobias Weigel (DKRZ) 22 Collections can be realized through graphs 10876/B10876/A 10876/collectio n1 10876/B

23. Tobias Weigel (DKRZ) 23 What must be stored persistently? Minimal metadata (key- metadata) Checksum PID creation time stamp Graph structure (links) Collection membership static dynamic

24. Tobias Weigel (DKRZ) 24 Levels of preservation 1010 1010 1010 101 Primary level of preservation Secondary level of preservation 10876/abc123 Minimal metadata

25. Tobias Weigel (DKRZ)  Relation types must be standardized.  Research Data Alliance WG ‘PID Information Types’ WG ‘Type Registry’ collections? 25 PIDs are a topic for international collaboration 10876/A 10876/C10876/B 10876/A 10876/collect ion1

26. Tobias Weigel (DKRZ) 26 Usage scenario: Provenance as a DAG cdo t Data object PID Link „was derived from“

27. Tobias Weigel (DKRZ) How do we actually use PIDs? Software 27

28. Tobias Weigel (DKRZ)  For technical reasons key-metadata is unique feature that is required for PID graphs  For practical reasons – examples: ARKs and URNs lack wide adoption and support PURL maintenance is not clear LSIDs in older literature are not persistent  Handle System has an operational perspective I am biased towards the Handle System

29. Tobias Weigel (DKRZ)  Developed by CNRI Corporation for National Research Initiatives  Registered trademark  Fee for registering new prefixes (e.g. 10876)  Customers e.g. US military International DOI Foundation 29 What is the Handle System?

30. Tobias Weigel (DKRZ) URL: www.dkrz.de Checksum:... 30 How does the Handle System work? Prefix DB 1001 10876 1234 Central resolution service 10876/100 100

31. Tobias Weigel (DKRZ) 31 What are Digital Objects? 10876/abc123http://example.com/xyz789

32. Tobias Weigel (DKRZ) 32 Build a stack of lightweight components LAPIS API for Persistent Identifier Services (on GitHub)

33. Tobias Weigel (DKRZ)  Weigel et al.: “A framework for extended persistent identification of scientific assets” (submitted to the Data Science Journal)  Duerr et al., doi:10.1007/s12145-011-0083-6 33 Further reading

34. Tobias Weigel (DKRZ) All slides available here: redmine.dkrz.de/seminar Thank you. 34

35. Tobias Weigel (DKRZ)  LTA application: Q4 2012, Q1 2013  EUDAT integration: 2014  CMIP6 + : 2014 35 The greater plan