Comparing the Performance of OAI-PMH with ResourceSync

1. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Comparing the Performance of OAI-PMH with ResourceSync Petr Knoth, Matteo Cancellieri Knowledge Media institute The Open University UK Martin Klein Research Library Los Alamos National Laboratory USA

2. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany “A single scientific repository is of limited value, real benefits come from the ability to exchange data within a network … … interoperability allows us to exploit today's computational power so that we can aggregate, data mine, create new tools and services, and generate new knowledge from repository content.” - COAR ResourceSync and repositories 2

3. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Protocols for data exchange are the blood of the scholarly communication system ResourceSync and repositories 3

4. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Aggregators and ResourceSync 4 ResourceSync (CORE FastSync) 3rd parties -data analysis - TDM

5. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Repository aggregators have large full text collections core.ac.uk stats: • 13,117,488 Hosted full texts • 135,539,113 Metadata records • ~78m Links to full text • 15TB of raw plain text • 4,123 Data providers 5

6. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Many OAI-PMH implementations challenges … Locating full text URLs in metadata Restrictions on full text downloading Sequential nature of OAI-PMH Failing resumption tokens Incremental updates Scalability Metadata interoperability Reliability No content harvesting support 6

7. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Speed of OAI-PMH implementations 7

10. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Aggregators have a lot of usage • January 2019 – CORE reached over 10M monthly active users for the first time • 571% increase from January 2018 • core.ac.uk by usage in the top 0.0009% of global websites 10

11. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Aggregator’s challenge • Stay up to date despite thousands of data providers • Efficiently expose large amounts of data to many users: • Human users • Machines (scalability!) • OAI-PMH implementations can hardly deal with the job: • Scalability • Metadata inconsistency • Supports for metadata harvesting only 11

12. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Research question 12 Is ResourceSync better suited for the job than OAI-PMH?

13. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany OAI-PMH - Background 13 http://openarchives.org/pmh/ • Recurrent metadata exchange from a Data Provider to Service Providers • XML metadata only • Repository centric • Devised 1999-2002, prior to REST, prior to dominance of web search engines

14. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany ResourceSync - Background 14 http://www.openarchives.org/rs/1.1/resourcesync • Synchronization of resources from a Source to Destinations • Web resources, anything with an HTTP URI & representation • Resource centric • Devised 2012-2013, leverages key ingredients of web interoperability, existing specifications, existing Search Engine Optimization practice

15. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany ResourceSync in a Nutshell 15

16. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany ResourceSync Capabilities 16

21. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Many to One - Aggregator 21

22. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany ResourceSync is based on Sitemaps 22 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"> <url> <loc>http://example.com/res1</loc> <lastmod>2013-01-02T13:00:00Z</lastmod> </url> <url> <loc>http://example.com/res2</loc> <lastmod>2013-01-02T14:00:00Z</lastmod> </url> … </urlset>

23. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany ResourceSync Resource List 23 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability="resourcelist" at="2019-06-11T09:00:00Z" completed="2019-06-11T09:00:44Z" /> <url> <loc>http://example.com/res1_metadata.xml</loc> <lastmod>2019-06-02T13:00:00Z</lastmod> <rs:md hash="md5:1584abdf8ebdc9802ac0c6a7402c03b6" length="823" type="text/xml" /> </url> </urlset>

24. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Resource List with Link 24 <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:rs="http://www.openarchives.org/rs/terms/"> <rs:md capability="resourcelist" at="2019-06-11T09:00:00Z" completed="2019-06-11T09:00:44Z" /> <url> <loc>http://example.com/res1_metadata.xml</loc> <lastmod>2019-06-02T13:00:00Z</lastmod> <rs:md hash="md5:1584abdf8ebdc9802ac0c6a7402c03b6" length="823" type="text/xml" /> <rs:ln href="http://example.com/res1_content.pdf" rel="describes" length="8876" type="application/pdf" /> </url> </urlset>

25. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany • Designed to allow synchronization of resources, not just metadata • Explicit link between metadata and the described resource • Not prescriptive about the metadata format • Web-centric • Push-based Change Notifications (WebSub) ResourceSync Characteristics 25

26. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany 1. Assess the speed of OAI-PMH implementations across repositories See results on slide #7 Comparative Analysis 26

27. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany 1. Assess the speed of OAI-PMH implementations across repositories 2. Understand the recall in full-text harvesting Comparative Analysis 27

28. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Recall of full-text harvesting – the power of the explicit full text link 28

29. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany 1. Assess the speed of OAI-PMH implementations across repositories 2. Understand the recall in full-text harvesting 3. Evaluate simulated metadata harvesting with ResourceSync implementations for: a) Standard Mode • Resources sync’ed via Resource Lists, one resource at a time (per HTTP transaction) b) Resource Dump Mode • Resources packaged into a Resource Dump, transferred via one HTTP transaction c) Batch Mode • Resources are packaged into partial and on-demand Resource Dumps, transferred via multiple HTTP transactions 4. Comparative Analysis 29

30. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Speed simulated ResourceSync implementations 30

31. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Speed simulated ResourceSync implementations 31

32. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Why On Demand Resource Dump • Many repositories have hundreds of OAI sets: • Cannot materialize (too much data and processing requirements) • Cannot rely on Resource List (too slow) • HATEOAS approach: https://blog.core.ac.uk/2018/03/17/increasing-the-speed-of-harvesting- with-on-demand-resource-dumps/ 32

33. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Recommendations for data providers • Adopt ResourceSync at a platform level (Eprints, Dspace, Fedora, etc.) • Many considerations: • Support Change Lists? Dump? Naming of Capability Lists? On Demand Dumps? How to link resources? WebSub? • Guidelines needed! • Resource List adoption only viable for small providers • Support for on-demand Resource Dumps needed! • ResourceSync Client-Server implementation available: https://github.com/resync/resync • CORE happy to benchmark repository platforms • LANL working on validator 33

34. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany • OAI-PMH implementations vary substantially in terms of number of records downloaded per second • ResourceSync provides up to 10 times faster harvesting speeds with Resource Dumps • On-demand Resource Dumps for optimization • Not yet part of the standard • Thanks to resource linking, low recall less of an issue! Take-aways 34

35. Comparing the Performance of OAI-PMH with ResourceSync @petrknoth @mart1nkle1n OR 2019, 06/12/2019, Hamburg, Germany Comparing the Performance of OAI-PMH with ResourceSync Petr Knoth, Matteo Cancellieri Knowledge Media institute The Open University UK Martin Klein Research Library Los Alamos National Laboratory USA