Collaborative Development of Multilingual Thesauri with VocBench (System Description and Demonstrator)

Abstract

VocBench is an open source web application for editing of SKOS and SKOS-XL thesauri, with a strong focus on collaboration, supported by workflow management for content validation and publication. Dedicated user roles provide a clean separation of competences, addressing different specificities ranging from management aspects to vertical competences on content editing, such as conceptualization versus terminology editing. Extensive support for scheme management allows editors to fully exploit the possibilities of the SKOS model, as well as to fulfill its integrity constraints. We describe here the main features of VocBench, which will be shown along the demo held at the ESWC15 conference.

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© Springer-Verlag Berlin Heidelberg 2011
Collaborative Development of Multilingual Thesauri with
VocBench (System Description and Demonstrator)
Armando Stellato1, Sachit Rajbhandari2, Andrea Turbati1, Manuel Fiorelli1,
Caterina Caracciolo2, Tiziano Lorenzetti1, Johannes Keizer2, Maria Teresa Pazienza1
1ART Group, Dept. of Enterprise Engineering
University of Rome, Tor Vergata
Via del Politecnico 1, 00133 Rome, Italy
{stellato,turbati,fiorelli,pazienza,lorenzetti}@info.uniroma2.it
2Food and Agriculture Organization of the United Nations (FAO)
Viale delle Terme di Caracalla, 00153 Rome, Italy
{sachit.rajbhandari,caterina.caracciolo,johannes.keizer}@fao.org
Abstract. VocBench is an open source web application for editing of SKOS and
SKOS-XL thesauri, with a strong focus on collaboration, supported by workflow
management for content validation and publication. Dedicated user roles provide
a clean separation of competences, addressing different specificities ranging from
management aspects to vertical competences on content editing, such as concep-
tualization versus terminology editing. Extensive support for scheme manage-
ment allows editors to fully exploit the possibilities of the SKOS model, as well
as to fulfill its integrity constraints. We describe here the main features of
VocBench, which will be shown along the demo held at the ESWC15 conference.
Keywords: Collaborative Thesaurus Management, SKOS, SKOS-XL
1 Introduction
In 2008, the AIMS group of the Food and Agriculture Organization of the United Na-
tions (FAO, http://www.fao.org/) fostered the development of a collaborative platform
for managing the Agrovoc thesaurus [1]: the “Agrovoc Workbench”. Later on, in the
context of a joint collaboration between FAO and the ART group of the University of
Tor Vergata in Rome (http://art.uniroma2.it), the system has been completely re-
thought as a fully-fledged collaborative platform for thesaurus management, available
free of charge and open source: VocBench. With respect to its predecessor, VocBench
complies with standard Semantic Web technologies, by relying on Semantic Turkey
[2], an RDF management platform already developed and currently maintained by the
ART team. In particular, VocBench natively supports the SKOS
1
W3C vocabulary for
representing thesauri and concept schemes, with its extension SKOS-XL
2
for extended
labels (i.e. labels reified as RDF resources, which can be described in turn).
1
http://www.w3.org/TR/skos-reference/
2
http://www.w3.org/TR/skos-reference/skos-xl.html

While providing a more thorough support for RDF, VocBench retains the focus on
multilingualism, collaboration and on a structured content validation & publication
workflow that characterized it yet from its infancy. The demo will provide a guided
tour through all of VocBench features and will let the user experience the editorial pro-
cess that accompanies the development of an authoritative resource.
2 A Quick Glance at VocBench Features
The feedback gathered from real thesaurus publishers guided the development of
VocBench: FAO and its partners provided great support for shaping interaction and
collaboration capabilities. Here follow the features that mostly characterize the system.
User Interface. VocBench has been conceived as a web application accessible through
any modern browser, therefore disburdening end users from software installation and
configuration. The user interface consists of multiple tabs, each one associated with
specific information and functionalities. A quick exploration of the available tabs is
sufficient to discover most of the VocBench functionalities. Figure 1 offers a typical
view of VocBench, with the concept tree on the left, and the description of the selected
concept on the right, centered on the term tab, listing all terms in the different languages
available for the resource. Concepts in the tree may be shown through their labels in all
of the selected languages for visualization. An option toggles between a view of pre-
ferred labels only, and all labels. The multilingual characteristics of VocBench are not
Figure 1. VocBench User interface showing a fragment of the AGROVOC thesaurus

limited to content management, as its interface is also localized in different languages,
currently: English, Spanish, Dutch and Thai.
Role-based Access Control. VocBench promotes the separation of responsibilities
through a role-based access control mechanism, checking user privileges for requested
functionalities through roles that users assume. A completely customizable access pol-
icy specifies roles and their assigned privileges. New roles can be created and existing
ones can be modified. The default policy recognizes typical roles and their acknowl-
edged responsibilities: Administrators, Ontology editors, Term editors (Terminolo-
gists), Validators and Publishers.
Formal Workflow and Recent Changes. Collaboration is essential for distributing
effort and reaching consensus on the thesaurus being developed. To facilitate collabo-
ration, VocBench provides an editorial workflow in which editors’ changes are tracked
and stored for approval by content validators. This workflow management is supported
by role-based access control, by providing users with different roles so to enforce the
separation between their responsibilities. In a collaborative environment, where users
may proactively edit a shared resource, it is important to have means for monitoring the
situation. Regarding this aspect, the ability to control recent changes to the thesaurus is
useful for detecting hot sections and coordinating with other editors. In VocBench, us-
ers can see recent changes both in the Web user interface and as an RSS feed.
Advanced Scheme Management. VocBench allows to manage thesauri organized
around multiple concept schemes. Users can switch across schemes by selecting them
through the relevant Schemes tab in the user interface. VocBench functionalities are
well-behaved with respect to schemes, as actions that would generate dangling concepts
(concepts not reachable through any tree-view) are forbidden, detailing the cause of the
impediment to the users. In any case, since data can be loaded from pre-existing sources
developed outside of VocBench, a fixing utility for dangling concept is available
through the UI, and will be part of a larger section dedicated to Integrity Constraints
Validation, especially thought for fixing violated SKOS constraints.
Metrics & SPARQL Querying. VocBench reports several metrics concerning the the-
saurus itself and the collaborative workflow. In addition to statistics and visualizations
provided by VocBench, users may formulate SPARQL 1.1 queries/updates to select
precise information, perform custom analytical tasks or modify the thesaurus bypassing
the standard editing functionalities. The SPARQL editor is based on the open source
Flint SPARQL Editor (https://github.com/TSO-Openup/FlintSparqlEditor), which pro-
vides syntax highlighting and completion, and has been customized to be fed with in-
formation from the edited thesaurus.
Alignment. From version 2.3, VocBench supports alignments to other thesauri. Cur-
rently, the creation of alignments can either be performed manually, by inserting URIs
as values of the various SKOS mapping properties, or be assisted in case of mappings
to other thesauri managed by the same instance of VocBench. In the latter case, a con-
cept-tree browser with advanced search interfaces facilitates the identification of the
best matching concepts from the targeted datasets.

3 Some Notes on Architecture and Technologies
Semantic Turkey, the RDF backbone of VocBench, offers an OSGi service-based layer
for designing and developing OWL ontologies and SKOS(XL) thesauri. A lightweight
Firefox interface is available for use as a desktop tool, which is now complemented by
VocBench, mainly differentiating for its collaborative nature and its focus on thesauri.
VocBench has a layered architecture consisting of a presentation and multi-user
management layer, a service layer and a data management layer. The first layer is im-
plemented as a Web application, powered by GWT (Google Web Toolkit,
http://www.gwtproject.org/). The other layers coincide with the Semantic Turkey RDF
management platform, equipped with an extension providing additional services ex-
pressly developed for VocBench. VocBench is also in charge of user and workflow
management, since these aspects are not covered by Semantic Turkey. User accounts
and tracked changes are stored in a relational database accessed through a JDBC con-
nector. The adoption of OSGi allows for plugging of extensions: in particular, other
than realizing additional services, different connectors for specific RDF middleware
and triple storage technologies can be provided. VocBench is currently shipped with a
connector for Sesame2 [3], supporting all of its storage/connection possibilities: in
memory, native, remote connection and their respective configurations. The remote
connection is particularly useful, as it allows VocBench to connect to Sesame2 compli-
ant triple stores (e.g. GraphDB [4]) without need for a dedicated connector. VocBench
RDF API are based on OWL ART (http://art.uniroma2.it/owlart/), an abstraction
layer supporting access to different triple stores. Different connectors can be imple-
mented from scratch in terms of those API, or by reusing middleware already bridged
through other existing connectors. For instance, the Virtuoso triplestore [5] is compat-
ible with the Sesame API, but requires a dedicated client library: it thus needs to be
introduced by a specific connector, though its implementation may be largely realized
as an extension of the already existing Sesame connector. Finally, particular attention
has been paid to system scalability, both on performance and maintenance aspects. To
this end, information is provided to the frontend as much as possible in an incremental
fashion (e.g. each level of the concept hierarchy, as nodes are expanded).
4 System Demo
In the demonstration, visitors will be guided through all of VocBench features, experi-
encing the editorial process that accompanies the development of an authoritative re-
source. The audience will initially be acquainted with the UI of the environment and
learn how to browse the loaded dataset in order to explore its content. Later on, they
will try the more common editing operations for creating, modifying and relating con-
cepts and (SKOS-XL reified) labels. Interested people will go through the full editorial
workflow, seeing how different roles will contribute to the evolution of the thesaurus.
The demo will be carried on real thesauri from a few of the large organizations that
are already using VocBench for maintaining their resources. These thesauri include:
- Agrovoc (Food and Agriculture Organization)

- Eurovoc (EU Documentation Office)
- Unified Astronomy Thesaurus (Harvard-Smithsonian Center for Astrophysics)
- Teseo (Italian Senate)
5 More about VocBench
This paper accompanies the demo of VocBench being held at the 12th Extended Seman-
tic Web Conference. More information about VocBench, an in-depth comparison with
other systems, user evaluation, lessons learned and insights on the future of the system,
can be found in [6], an article presented at the Research Track of this same conference.
5.1 Availability
VocBench is distributed as open-source under the Mozilla Public License
(https://www.mozilla.org/MPL/2.0/).
VocBench home page: http://vocbench.uniroma2.it/
Source code on Bitbucket: https://bitbucket.org/art-uniroma2/vocbench
A sandbox server for testing VocBench capabilities is hosted by courtesy of the Malay-
sian research center MIMOS Berhad at: http://202.73.13.50:55481/vocbench/
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