Citation Linking in Federated Digital Libraries

Eike Schallehn, Martin Endig, Kai-Uwe Sattler

Otto-von-Guericke-University MagdeburgInstitute for Technical and Business Information Systemshttp://wwwiti.cs.uni-magdeburg.de/

Third International Workshop on Engineering Federated InformationSystems (EFIS'2000)

19th-21st June 2000

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

2EFIS 2000

Overview

• Motivation• Architectural Overview

• Federation Service• Adapter Layer

• Citation Linking• Fundamentals• Implementation

• Conclusion

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

3EFIS 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)

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

4EFIS 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

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

5EFIS 2000

Architectural Overview

Federation Layer

Adapter Layer

Federation Service

...

AdapterAdapterAdapterAdapter

Higher Level Services

Common Interface / Unified Representation

website ofpublisher 2

proprietarydata ...

database ofpublisher 1 ...

SourceLayer

ApplicationLayer

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

6EFIS 2000

Architecture Overview: Federation Service

• FRAQL - 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

• ...

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

7EFIS 2000

Architecture Overview: Adapter Layer

• Adapters for websites and various databases

• special XML adapter for cooperative providers in WAN scenario

FRAQL Query Processor

QueryEvaluator

QueryTranslator XML

Parser

ResultTranslator

Sou

rce

Des

crip

tion

XS

LT

XML

XM

L A

dapt

er

Dat

a S

ourc

e

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

8EFIS 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

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

9EFIS 2000

Citation Linking:Fundamentals

• Simple target schema:Publ(Key, A1, ..., An, {Ref1, ...,

Refm})

• BibKey set of global identifiers • unique source name• OID set of locally unique identifiers

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

10EFIS 2000

Citation Linking:FRAQL Implementation

• FRAQL 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);

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

11EFIS 2000

Citation Linking:FRAQL 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));

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

12EFIS 2000

Citation Linking:FRAQL 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“;

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

13EFIS 2000

Citation Linking:FRAQL Implementation IV

A d a9 8A d a9 8S co 9 8

D a tab asesD a tab asesD ig . L ib ra rie s

A d am sA d am sS co tt

S co 9 8M e y 9 2M o o 9 4

K ey Title A u tho rs R eferences

M o o 9 4……

S Q L……

M o o re……

………

K ey Title A u tho rs R eferences

M o o 9 4M e y 9 2

M o o 9 4M e y 9 2 a

P u b l_ 2P u b l_ 3

key id sou rce

A d a9 8S co 9 8

P u b l_ 1P u b l_ 1

D a tab asesD ig . L ib ra rie s

A d am sS co tt

id sou rce title au tho rs

M o o 9 4 P u b l_ 2 S Q L M o o re

id sou rce title au tho rsS co 9 8M e y 9 2 aM o o 9 4

id sou rce re f_ id re f_ source

A d a9 8A d a9 8S co 9 8

P u b l_ 1P u b l_ 1P u b l_ 1

P u b l_ 1P u b l_ 3P u b l_ 2

Local re lation src1.Publ Local re lation src2.Publ

M apping tableM apPubl

Im port re lation Publ_1Im port re lation R ef_1

Im port re lation Publ_2

19th - 21st June 2000

Eike Schallehn Martin Endig

Kai-Uwe Sattler

14EFIS 2000

Conclusion and Outlook

• Integration system for bibliographical data• based on FRAQL 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