1. Citation Linking in Federated Digital Libraries Eike Schallehn, Martin Endig, Kai-Uwe Sattler Otto-von-Guericke-University Magdeburg Institute for Technical and Business Information Systems http://wwwiti.cs.uni-magdeburg.de/ Third International Workshop on Engineering Federated Information Systems (EFIS'2000) 19th-21st June 2000

2. Eike Schallehn Martin Endig Kai-Uwe Sattler 2 EFIS 2000 Overview Motivation Architectural Overview Federation Service Adapter Layer Citation Linking Fundamentals Implementation Conclusion

3. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 3 EFIS 2000 Motivation Digital libraries and electronic catalogues can cover only limited amounts of publications Citation information offered by various sources Current strategies: citation information only available for locally maintained publications minimum set of citation information for identifying non- local publications universal citation database globally unique identifier for publications (DOI)

4. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 4 EFIS 2000 Motivation II Integration of bibliographical metadata has to include citation data Advantages: improves accesibility of publications implicit knowledge becomes explicit and usable for derivation of higher level information Major tasks: common platform based on integration service for bibliographical data required global identification of objects

5. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 5 EFIS 2000 Architectural Overview Federation Layer Adapter Layer Federation Service... Adapter Higher Level Services Common Interface / Unified Representation website of publisher 2 proprietary data... database of publisher 1... Source Layer Application Layer

6. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 6 EFIS 2000 Architecture Overview: Federation Service F RA QL - Federation Query Language supports loosely coupled database federations mechanisms for conflict resolution Import relations are provided by adapters complex restructuring mechanisms including value mappings Integration relations as global views same-object identification and tuple reconcilation definition based on schema elements possible...

7. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 7 EFIS 2000 Architecture Overview: Adapter Layer Adapters for websites and various databases special XML adapter for cooperative providers in WAN scenario F RA QL Query Processor Query Evaluator Query Translator XML Parser Result Translator Source Description XSLT XML XML Adapter Data Source

8. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 8 EFIS 2000 Architecture Overview: Related Issues Source descriptions various systems have limited query capabilities aim: pass queries with a high as possible selectivity through to data sources Integration of semi-structured data Cooperative vs. non-cooperative providers

9. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 9 EFIS 2000 Citation Linking: Fundamentals Simple target schema: Publ(Key, A 1,..., A n, {Ref 1,..., Ref m }) BibKey set of global identifiers unique source name OID set of locally unique identifiers

10. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 10 EFIS 2000 Citation Linking: F RA QL Implementation F RA QL schema in first normal form  types PubType and RefType Import relations according to the type definitions create table Publ_1 of PubType as import from src1.Publ ( id is Key, source is “Publ_1“, title is Title, authors is Authors);

11. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 11 EFIS 2000 Citation Linking: F RA QL Implementation II Mapping table MapPubl(key,id,source) from local reference keys to global keys is required create table Ref_1 of RefType as import from src1.Publ ( id is Key, source is “Publ_1“, ref_id is @MapPubl(References,key,id,References), ref_source is @MapPubl(References,key,source,“Publ_1));

12. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 12 EFIS 2000 Citation Linking: F RA QL Implementation III Integration relations can be defined using metadata facilities: create table References of RefType as select t2.* from catalog.tables t1, $(t1.tablename) t2 where t1.type_name = “RefType“;

13. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 13 EFIS 2000 Citation Linking: F RA QL Implementation IV

14. 19th - 21st June 2000 Eike Schallehn Martin Endig Kai-Uwe Sattler 14 EFIS 2000 Conclusion and Outlook Integration system for bibliographical data based on F RA QL federation service special adapter for this scenario Platform for the integration of citation linking information Outlook: critical issue: efficient generation of mapping table integration of citation databases integration with DOI mechanism