=Paper=
{{Paper
|id=Vol-1608/paper-05
|storemode=property
|title=Linking data in digital libraries: the case of Puglia Digital Library
|pdfUrl=https://ceur-ws.org/Vol-1608/paper-05.pdf
|volume=Vol-1608
|authors=Tommaso Di Noia,Azzurra Ragone,Andrea Maurino,Marina Mongiello,Maria Paola Marzocca,Giuseppe Cultrera,Mauro Paolo Bruno
|dblpUrl=https://dblp.org/rec/conf/esws/NoiaRMMMCB16
}}
==Linking data in digital libraries: the case of Puglia Digital Library==
https://ceur-ws.org/Vol-1608/paper-05.pdf
Linking data in digital libraries: the case of
Puglia Digital Library
Tommaso Di Noia1 , Azzurra Ragone2 , Andrea Maurino2 , Marina Mongiello1 ,
Maria P. Marzocca3 , Giuseppe Cultrera3 , Mauro P. Bruno4
1
Polytechnic University of Bari, Bari, Italy firstname.lastname@poliba.it
2
University of Milano-Bicocca, Milano, Italy lastname@disco.unimib.it
3
Innovapuglia SpA, Valenzano (BA), Italy
{mp.marzocca,g.cultrera}@innova.puglia.it
4
Regione Puglia, Bari, Italy mp.bruno@regione.puglia.it
Abstract. The digital revolution has been a big shift in the creation,
publication and storage of our digital heritage. New file formats and
supports have followed over the years to produce and reproduce audio,
photos and video. Based on these observations, the Puglia region started
the Puglia Digital Library project with the aim to collect in a single
public collection all the digital contents related to Puglia.
Due to its public nature, all the items available in the collection have
been described using also RDF-based annotations and the final dataset
has been exposed via a SPARQL endpoint. During the data-engineering
process, attention has been paid in the selection of shared vocabular-
ies thus allowing a plain integration with other projects such as Cul-
tura Italia, Europeana, Musei D’Italia, Internet Culturale and Sistema
Archivistico Nazionale. Thanks also to its links to DBpedia, Schema.org,
FOAF and GeoNames, Puglia Digital Library can be considered as a new
player in the Linked Open Data cloud.
1 Introduction
A Digital Library (DL) is a collection of digital resources (text, visual and audio
material, etc.) which are stored in knowledge bases or databases. It has to pro-
vide means to make easy the storage and retrieval of media in the collection, as
well as to link resources among various digital libraries thus allowing the sharing
of knowledge among different providers. As of today, we have many examples of
Digital Libraries maintained by institutions or organizations (e.g. Europeana,5
World Digital Library6 ), by libraries (National Science Digital Library7 ) or aca-
demic institutions (Harvard University Library8 ).
In order to be as effective as possible in the whole document management
chain, DLs are designed as very complex information systems which include
5
http://europeana.eu/portal/
6
https://www.wdl.org
7
https://nsdl.org/
8
http://library.harvard.edu/
28 A. Adamou, E. Daga and L. Isaksen (eds.)
digital document preservation, distributed database management, information
filtering, information retrieval, intellectual property right management, query
answering, resource discovery and selective dissemination of information [8]. The
research efforts of the last years have been focused on ways to associate meta-
data to resources stored in DLs with the aim to provide an easy cataloging and
browsing of the collections themselves.
More recently, the Linked Data initiative [10] has gained momentum as a
set of best practices for publishing and connecting structured (open) reusable
data on the Web [11]. In this respect, the Linked Open Data (LOD) initiative
meets the need for a broader cooperation among different DLs, supporting the
sharing of knowledge and resources among them and then a conceptual shift
from document-centric to data-centric and metadata-based approaches [1]. In-
deed, the reuse of knowledge coming from other repositories can be effective
only if data are provided with common and shared metadata. Metadata are a
key element in the digital library domain [13]. Indeed, cultural heritage institu-
tions (museums, archives, libraries) use metadata, as well as thesauri to describe
objects in their collections. Linking these metadata with datasets in the Linked
Data cloud (GeoNames, DBpedia, FOAF, ecc.) greatly improves reusability and
integration of diverse Digital Libraries [3]. The effectiveness in the use of LOD
datasets to annotate digital resources in a DL is also witnessed by some success-
ful use cases such as the one of the German National Library9 or the British
National Library10 as well as the case of the National Library of Spain11 and of
the National Library of France.12 Moreover, many cultural-heritage institutions
have started to explore the benefits of LOD as a means for resource discovery
for their hidden treasures [12].
There are many benefits in using linked metadata for DLs, among these:
metadata openness and sharing, easiness in information discovery, identification
of resource usage patterns, facet-based navigation and metadata enriched with
links [1]. This latter has a very important role as makes the user able to navigate
among DLs and external information providers. If all the DLs adopted the Linked
Data principles they would play a dominant role in the Linked Data cloud as
they store a great amount of legacy bibliographic and authority-list data [1]. In
order to support the widely adoption of LOD in DLs, some general approaches to
data management and transition from metadata to triples needs to be explored;
this results in a fundamental shift in metadata design and development that has
important implications for controlled vocabularies in terms of data cleanup and
preparation [12].
In this paper we present the Puglia Digital Library 13 project (PugliaDL),
whose digital resources are described according to standard vocabularies and
can be exposed in the LOD cloud as they follow the well-known Linked Data
9
http://www.dnb.de/EN
10
http://www.bl.uk/bibliographic/datafree.html
11
http://datos.bne.es/
12
http://data.bnf.fr/
13
http://www.pugliadigitallibrary.it/
1st Workshop on Humanities in the Semantic Web (WHiSe 2016) 29
principles.14 The remainder of this paper proceeds as follow. Section 2 reviews
some relevant work in the field of DLs focused on linking, sharing and reuse of
data. Section 3 describes all the aspects related to PugliaDL including its Linked
Data model. Section 4 is devoted to show some examples of resources available
in PugliaDL. Conclusion closes the paper.
2 Related Work
In the last decades DLs have become very popular and several scientific in-
vestigations and practical efforts were put in place on them: there has been a
considerable amount of effort in designing vocabularies, metadata standards, and
thesauri to annotate DLs objects, so this section cannot be exhaustive.
Thousands of DLs are emerging around the world, crossing all disciplines
and media, some are small community-based initiatives, while others are man-
aged by e.g. public institutions, as national libraries offering a wide range of
cultural treasures in multiple media [8]. Finding a unique definition of DL is
almost impossible, as, during the years, different definitions has been proposed
in the literature. The Digital Library Federation (DLF) puts more emphasis on
the organizational aspects, stating that DLs are organizations that provide the
resources to select, offer intellectual access to, distribute, preserve the integrity
of, and ensure the persistence over time of collections of digital works so that
they are available to a community or set thereof.15 Borgman [4] states: “DLs
are a set of electronic resources and associated technical capabilities for creating,
searching and using information. The content of DLs includes data and meta-
data”. The latter definition is important as it puts the accent on the presence of
metadata, which are fundamental to classify and retrieve information in DLs.
At the beginning of the 2000’s in the effort of managing and organizing DLs,
several initiatives emerged as OCLC,16 a global library cooperative with thou-
sands of library members in more than 100 countries. Several DL Directories
exist, among the others, the Library of Congress,17 the Digital Library Direc-
tory18 and the Alexandria Digital Research Library.19 Europeana [9] is a DL
linking more than 40 million digital items from the cultural and heritage domain
(artworks, books, video, artefacts, sounds) that have been digitized throughout
Europe. Europeana is a large-scale aggregator where the original data is ab-
stracted to a common format and schema [3]. Europeana is a collector of digital
objects, it does not store the digital content, but it just collects metadata about
the items. Indeed, Europeana collects metadata about digitized content of over
3300 Europes galleries, libraries, museums, archives, etc. When the users find a
content of interest, they are linked to the original site (content provider) that
14
https://www.w3.org/DesignIssues/LinkedData.html
15
DLF, April 21, 1999
16
https://www.oclc.org/
17
https://www.loc.gov/collections
18
http://www.digitallibrarydirectory.com/
19
http://www.alexandria.ucsb.edu/
30 A. Adamou, E. Daga and L. Isaksen (eds.)
holds the content itself, e.g. a museum, a library, a regional archive. To make the
information searchable using metadata, initially, an extended Dublin Core model
was used, named Europeana Semantic Elements. Now this has been superseded
by a richer metadata standard named Europeana Data Model20 (EDM), based
on Semantic Web languages (OWL, RDF). EDM incorporate community stan-
dard such as LIDO21 for museum, EAD22 for archives or METS23 for digital
libraries. The EDM has also been used by other DLs. The Europeana approach,
on the one side ensures great consistency and interoperability. Unfortunately, on
the other side it may lose the richness of the original data [3].
The effort for producing standardized metadata to catalogue DLs started in
the nineteenth century with regional and international consortia that tried to
institute rigorous cataloguing principles and rules, just to cite a few AACR,24
MARC,25 ISBD,26 FRBR,27 RDA28 [1]. Metadata standards such as FRBR and
RDA are more devoted to human consumption rather than machine process-
ing, indeed when these metadata are implemented using a technical format like
MARC they show problems of metadata duplication, data inconsistency, lack of
granularity and complexity [6, 1]. The solution to shift from a document-centric
view (typical of the previous standards) to a data-centric view lies down in the
adoption of LOD for metadata modelling, encoding, representation and sharing.
The use of LOD is also justified by the need to make DLs freely and openly
accessible, other than in a shareable, extensible and re-usable format[14]. In this
direction, the Library of Congress and the Stanford University Libraries29 have
paved the way since 2011, followed by the Europeana initiative and the British
Library, that have both developed a semantic metadata model compliant with
LOD specifications [5, 9].
The task of search and discovery in DLs has often been faced using metadata
describing information objects (e.g., documents). As the one of the Dublin Core
Metadata initiative (DCMI) [7] focused on developing small usable set of vocab-
ulary terms that can be used to describe the essential features of web resources
(video, images, web pages, etc.), as well as physical resources like artworks,
books, ecc. The Dublin Core Metadata can be used for both resource descrip-
tions as well as to combine various metadata standards with the aim to provide
interoperability among the metadata vocabularies in the LOD cloud. The cur-
rent set of the Dublin Core vocabulary is composed by the DCMI Metadata
Terms, all these terms are defined as RDF properties.
20
http://pro.europeana.eu/page/edm-documentation
21
www.lido-schema.org/
22
http://www.loc.gov/ead/
23
http://www.loc.gov/mets/
24
Anglo-American Cataloguing Rules, 1967
25
MAchine-Readable Cataloguing, 1960
26
International Standard Bibliographic Description for Monographic Publications,1971
27
Functional Requirements for Bibliographic Records, 1996
28
Resource Description and Access, 2010
29
http://library.stanford.edu/
1st Workshop on Humanities in the Semantic Web (WHiSe 2016) 31
3 Puglia Digital Library
Puglia Digital Library (PugliaDL) was conceived with the aim to preserve the
memory of the regional heritage and to enable its sharing and reuse. For this
reason PugliaDL wants to become a producer and supplier of LOD related to
the regional heritage, making available data that usually are hard to find. The
PugliaDL is a multimedia archive of books, magazines, newspapers, photographs,
sounds and audiovisual materials, museum objects, historical and artistic sites,
etc. Having in mind a DL were the information is open and shared, a key role is
played by the services that allow the sharing of knowledge from and to national
and international aggregators using standard metadata and LOD as access point
to the DL. At the moment PugliaDL collects about 40 digital collections and
1700 resources organized with respect to three main levels: topic, collection,
digital resource. PugliaDL mainly exposes its data on the Web in an ad-hoc
Web portal where each digital resource has a preview (sound or picture), a brief
description, a summary sheet, a map with the resource location, and can be
downloaded. For what concerns books, it is possible to virtually browse them
page by page; in this way it is possible to consult any book, even fragile and
precious ones. In describing resources, a set of standard metadata and controlled
vocabularies is used in order to favor interoperability. The PugliaDL is the only
digital library in Italy that can interact with other systems, as Cultura Italia30
(and through this with Europeana), Musei d’Italia,31 Internet Culturale,32 SAN-
Sistema Archivistico Nazionale.33 The sets of metadata used by the PugliaDL
are depicted in Table 1.
The controlled vocabularies are:
– DCMIType (DCMI Type Vocabulary)
– PICO Thesaurus (that allow interoperability with Cultura Italia)
– Vocabularies ICCD (Italian standard for cataloging)
– AAT (Art & Architecture Thesaurus)
– TGN (Thesaurus of Geographic Names)
3.1 Puglia Digital Library : data modeling
The Puglia Digital Library is the pilot project in the Puglia region in the field of
LOD. With reference to the 5-stars model proposed by Tim Berners-Lee34 , the
PugliaDL publishes its data both in 3- and 5-stars level. The choice is justified
by the fact that data published as CSV or XML can be exploited also by users
that do not have knowledge about RDF and SPARQL. The data of PugliaDL are
in the 5-stars level (LOD) as data are linked in the Semantic Web with external
sources (DBpedia, GeoNames, etc.). Before publishing any data, the first step
30
http://www.culturaitalia.it
31
http://www.culturaitalia.it/opencms/museid/index_museid.jsp?language=en
32
http://www.internetculturale.it/opencms/opencms/it/
33
http://san.beniculturali.it
34
https://www.w3.org/DesignIssues/LinkedData.html
32 A. Adamou, E. Daga and L. Isaksen (eds.)
DC Dublin Core Metadata Initiative
DDI Data Documentation Initiative
EAC-CPF Encoded Archival Context - Corporate Bodies, Persons, and
Families
EAD Encoded Archival Description finding aid
FGDC Federal Geographic Data Committee metadata
ISO 19115 2003 NAP North American Profile of ISO 19115:2003 descriptive metadata
LC-AV Technical metadata specified in the Library of Congress A/V
prototyping project
LOM Learning Object Model
MARC MAchine-Readable Cataloging
MAG Administrative and Management Metadata
METSRIGHTS TSRights Declaration Schema
MODS Library of Congress Metadata Object Description Schema
NISOIMG NISO Technical Metadata for Digital Still Images (MIX)
PREMIS PREservation Metadata: Implementation Strategies
TEIHDR Text Encoding Initiative Header
TEXTMD textMD Technical metadata for text
VRA Visual Resources Association Core
Table 1: Sets of metadata used by the Puglia Digital Library
is their analysis with the aim to identify the data that should be published by
following the criteria of integrity, coherence and completeness. The editorial staff
of PugliaDL has defined some publishing rules, among these the fact that each
collection should contain at least 5 digital resources (dr ) and that to each dr
the following metadata should be valued and published in an open format:
– Identifying data: title, ID, description, collection, subject, etc.
– Category data: genre, topic, etc.
– Resource data: title, author, chronological information, etc.
– Geographical data: location, geographic coordinates, curator, etc.
– Technical data: digital format, quality, etc.
– Data on accessibility: the copyright holder, license, etc.
All the data used to describe a dr are released using a CC0 license.35 In
the publishing phase the set of metadata is chosen with reference to the Italian
legislation36 rules. The collections of the PugliaDL are also published on the
Open data portal of the Puglia Region.37 One of the added values of using Linked
Data technologies in a DL is the possibility to place a particular cultural asset in
a proper context. Indeed, it is not possible to describe a cultural asset without
reference to its historical period and style, as well as, its geographic location.
35
https://creativecommons.org/publicdomain/zero/1.0/
36
Italian National guidelines for the valorization of public sector information published
by the Agency for Digital Italy (AgID 2014)
37
http://dati.puglia.it/
1st Workshop on Humanities in the Semantic Web (WHiSe 2016) 33
Consider for instance Medieval art. There are different styles of Romanesque in
different Italian regions: the Apulian Romanesque as well as the Lombard and
Pisan Romanesque, and each one has its own characteristics. Thanks to Linked
Data we can capture all these geographical and historical relations.
3.2 Resource annotation in Puglia Digital Library
Each resource in the system is described in accordance with existing ontologies,
to make the system itself highly interoperable. The ontology chosen to describe
such resources is CIDOC-CRM,38 developed by ICOM,39 which is the leading
conceptual model for the heritage sector. Specifically its OWL implementation
(Erlangen CRM/OWL40 ) has been adopted as more suitable for DLs. Such an
ontology is able to model the interweaving of semantic relations among temporal
and geographical dimensions, people, material and immaterial object descrip-
tions. As a way of example, a video about the Divine Comedy can be linked to
the video resource, or to its theatrical opera staged at the Nuovo Teatro Verdi
located in Brindisi and to its director Eimuntas Nekroŝius.
Furthermore, the CIDOC-CRM ontology is highly interoperable as it is mapped
to several other ontologies.41 PugliaDL itself uses standards that are all mapped
to such ontologies: Dublin Core [7], EAD,42 VRA,43 ICCD,44 EDM45 and PICO.46
The PICO Application profile mapping47 has been the main reference docu-
ment to create the RDF annotations in PugliaDL. Indeed, this allows to exchange
data with Cultura Italia and, through that, with Europeana. However, CIDOC-
CRM has some limitations in describing multimedia resources, e.g. it does not
have properties to describe technical details, like data rate mode, mimeType,
channel configuration, etc. For this reason, PugliaDL also adopted other ontolo-
gies to overcome such limits, including Dublin Core, DBpedia,48 Schema.org,49
FOAF50 and SKOS.51
In the following example one of the limitations of CIDOC is highlighted, in
the representation of the asset location:
38
http://www.cidoc-crm.org/
39
http://icom.museum/
40
http://erlangen-crm.org/
41
http://www.cidoc-crm.org/crm_mappings.html
42
https://www.loc.gov/ead/
43
https://www.loc.gov/standards/vracore/
44
http://www.iccd.beniculturali.it
45
http://pro.europeana.eu/page/edm-documentation
46
http://www.culturaitalia.it/opencms/export/sites/culturaitalia/
attachments/documenti/picoap/picoap1.0.xml
47
http://www.culturaitalia.it/opencms/documentazione_tecnica_en.jsp
48
http://dbpedia.org
49
http://schema.org
50
http://www.foaf-project.org/
51
https://www.w3.org/2004/02/skos/
34 A. Adamou, E. Daga and L. Isaksen (eds.)
Bari
In such a description it is impossible to distinguish among Municipality, Dis-
trict or Region. While by integrating the DBpedia ontology it is possible to
specify a property for each geographic area: dbp:locationCity, dbo:province,
dbo:region, dbo:address. At the same time, Schema.org provides specific vo-
cabularies for data with reference to audio, video, images, texts. FOAF is useful
to model data about authors of resources. Finally, geospatial information are
described through LinkedGeoData52 and Geonames.53
3.3 Linking Puglia Digital Library to the Linked Data cloud
The digital resources of PugliaDL have been linked to external vocabularies and
datasets of the Linked Data cloud to enrich the information provided with each
resource. DBpedia is our main reference point. PugliaDL URIs are linked to
DBpedia resources, especially for what concerns category data and geographical
data, other than resource name, whenever present. Often, the author’s name was
not present in DBpedia, especially for local artists; for this reason we created an
Authority File to be linked to VIAF54 (Virtual International Authority File).
VIAF is an international standard, accessible in RDF, that collects records
coming from several authority files and gives them URIs, supporting in this way
the search for author names independently of the language or of the alphabet. For
what concerns geographical data, other than DBpedia, we linked our resources
also with LinkedGeoData a broad geographical RDF knowledge base, based on
data from Open Street Map, and interconnected with DBpedia and GeoNames.
In the near future, we want to also integrate the service Linked Open Street
Map (LOSM) [2] in PugliaDL.
With the aim to enhance the semantics of the data, we use controlled vo-
cabularies to disambiguate terms in dependence of the context and to resolve
synonymy and homonymy. For this reason we link to vocabularies of the Getty
Research Institute55 that, recently, have been released as Linked Open Data.56
The Getty Research Institute vocabularies are constantly updated and compli-
ant with international cataloging standards (e.g., VRA, CIDOC CRM, CCO,57
etc.). They use a specific terminology for cultural and bibliographic fields and
52
http://linkedgeodata.org/
53
http://www.geonames.org/ontology
54
https://viaf.org/
55
http://www.getty.edu/research/
56
http://www.getty.edu/research/tools/vocabularies/lod/
57
http://cco.vrafoundation.org/
1st Workshop on Humanities in the Semantic Web (WHiSe 2016) 35
are accessible via SPARQL endpoints.58 At the moment the vocabularies avail-
able as LOD are: Art & Architecture Thesaurus (AAT), Union List of
Artists Names (ULAN) and Getty Thesaurus of Geographic Names
(TGN). These vocabularies have been of great use as they are inter-linked, share
the same data structure, are multilingual, and each term is identified by an ID59 .
Another vocabulary is the PICO Thesaurus, created by Cultura Italia. It
is multilingual, compliant with RDF and SKOS, released in LOD format and
it allows one to classify each resource with respect to its specific cultural do-
main. Each term in the vocabulary is identified by an URI. In the context of
PugliaDL it has been mainly used to link keywords that identify the digital
resource from a contextual and temporal point of view.60 The interoperability
is obtained thanks to the Open Archives Initiative Protocol for Metadata Har-
vesting 61 (OAI-PMH) that supports repository interoperability. Data Provider
repositories expose structured metadata via OAI-PMH, while Service Providers
make OAI-PMH service requests to harvest that metadata. Thanks to OAI-
PMH protocol PugliaDL is linked to Europeana and to the LOD resources of
the aforementioned LOD portals.
From a technological point of view, PugliaDL uses OpenLink Virtuoso ad
triple-store and LodView as RDF viewer and IRI dereferencer. In Figure 1, the
resource “Masseria Aprile - Spazio Interno” belonging to PugliaDL is depicted
in its HTML rendering by LodView.
4 PugliaDL Linked Data in action
In this section we highlight how the PugliaDL is highly inter-operable thanks to
properties that allow the linking with external dataset.
Content type. In order to model the type of content of digital resources
(e.g. manuscript, film poster, book, farm etc.) we can use the following prop-
erties:62 crm:P2_has_type, dcterms:type, schema:category, dbo:category,
dbp:category. The values of such properties are linked both to the terms of
Art & Architecture Thesaurus (AAT) and to DBpedia. As a way of ex-
ample, let us look at the PugliaDL resource “Il Gattopardo”; the digital resource
is the film poster of the famous 1963 movie “The Leopard”.
a crm:E38_Image,
rdfs:Resource , schema:ImageObject , dbo:Image , dbp:Image ;
rdfs:label "Il Gattopardo" ;
crm:P2_has_type ,
;
58
http://vocab.getty.edu/sparql
59
As a way of example, see the resource poster at http://vocab.getty.edu/aat/
300027221
60
As a way of example the 10th cent. A.D. is linked with the URI
http://www.culturaitalia.it/pico/thesaurus/4.1#http://culturaitalia.
it/pico/thesaurus/4.1#sec_x_d_c
61
https://www.openarchives.org/OAI/openarchivesprotocol.html
62
All the prefixes we use are from http://prefix.cc.
36 A. Adamou, E. Daga and L. Isaksen (eds.)
Fig. 1: An example of resource available in PugliaDL and displayed via LodView
dbo:category ,
;
schema:category ,
.
The above example clearly shows that we preferred to add redundant properties
in order to ease the reuse and a zero-effort interoperability with other datasets.
Whenever possible we added both redundant properties and redundant resources
(even when they could be connected via a owl:sameAs relation).
Resource author. As for the modeling of authors and their data we may
use the following properties: crm:P14_carried_out_by, dc:creator, dcterms:
creator, schema:author, dbo:author, dbp:author, foaf:maker.
Geographical data. Data about cities are modeled via properties linked to
DBpedia and LinkedGeoData as well as to Getty Thesaurus of Geo-
graphic Names (TGN), among these: dcterms:spatial, dbo:locationCity,
dbo:city, dbp:locationCity, dbp:city. The play Macbeth by Francesco Maria
Piave will be described together with geographical information as:
a crm:E33_Linguistic_Object,
rdfs:Resource , schema:CreativeWork , dbo:WrittenWork ;
rdfs:label "Macbeth" ;
crm:P14_carried_out_by "Francesco Maria Piave" ;
dc:creator "Francesco Maria Piave" ;
schema:author "Francesco Maria Piave" ;
dbo:author "Francesco Maria Piave" ;
dbp:author "Francesco Maria Piave" ;
1st Workshop on Humanities in the Semantic Web (WHiSe 2016) 37
foaf:maker "Francesco Maria Piave" ;
dcterms:spatial
,
,
, ;
dbo:locationCity
,
,
, ;
dbp:city ,
,
,
.
Data about the Region is modeled by using the following properties: dbo:region,
dbp:region, dcterms:spatial. Then, with reference to the digital resource “Il
Gattopardo” we can add geographical information as in the following:
a crm:E38_Image,
rdfs:Resource , schema:ImageObject , dbo:Image , dbp:Image ;
rdfs:label "Il Gattopardo" ;
crm:P2_has_type ,
;
dbo:category ,
;
schema:category ,
;
dcterms:spatial
, ,
, ,
,
;
dbo:region
, ,
,
;
dbp:region
, ,
,
.
Finally, with reference to the properties to model keywords that identify the re-
source we use the following properties that are linked to Pico Thesaurus: crm:
P2_has_type, dc:subject, dcterms:subject, schema:category, dbo:category,
dbp:category.
a crm:E38_Image ,
rdfs:Resource , schema:ImageObject , dbo:Image , dbp:Image ;
rdfs:label "Il Gattopardo" ;
crm:P2_has_type ;
dc:subject ;
schema:category ;
dbo:category ;
dbp:category .
5 Conclusion
We presented Puglia Digital Library project, whose main aim is to preserve the
memory and the beauty of the Puglia region heritage as well as to promote
its sharing and reuse. All the items in the collections available in PugliaDL
38 A. Adamou, E. Daga and L. Isaksen (eds.)
have been described using also RDF annotations in order to be part of the
LOD cloud. There are many benefits in using linked metadata for DLs; among
these, the easiness of the process of information discovery and sharing. Indeed,
the PugliaDL collections, thanks to their semantic annotations, can be easily
integrated in other DLs projects such as Europeana. The PugliaDL dataset has
been designed having interoperability in mind and this is the main reason why
more than one standard vocabulary has been adopted to model properties and
resources of the RDF triples.
Acknowledgements The authors acknowledge partial support of PON03PE 00136 1
Digital Services Ecosystem: DSE and Progetto Corvallis.
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