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RE: SKOS API and web-service

From: Tudhope D S (AT) <dstudhope@glam.ac.uk>
Date: Mon, 20 Apr 2009 18:47:16 +0100
Message-ID: <0BA7EE4D4646E0409D458D347C508B780577541A@MAILSERV1.uni.glam.ac.uk>
To: "Alistair Miles" <alistair.miles@zoo.ox.ac.uk>, "Johan De Smedt" <johan.de-smedt@tenforce.com>
Cc: <public-esw-thes@w3.org>, <public-swd-wg@w3.org>
Hi - following up on this and Al's subsequent email

wrt other implementations, i know doug tudhope and ceri binding have
an implementation of the skos web service api with some extensions,
but i don't know what the release status is.
Ceri Binding developed a set of web services, based upon SKOS Core data
model (v1) for the purposes of the STAR project [3]. The services
currently provide term look up across the thesauri held in the system,
along with browsing and semantic concept expansion within a chosen

The service is based on a subset of the SWAD Europe SKOS API with
extensions for concept expansion. Details and the API at
(may need to copy/paste the url to avoid our email server) 
and background references at [1,2], including a review of previous work
on KOS APIs and use patterns. Anyone interested is welcome to inspect
the API or download a client demonstrator of basic functionality.

SKOS_WS is a SOAP web service written in C#, running on Microsoft .NET
framework. The current implementation is SOAP based but we believe that
a REST based http version would not a big step. We haven't made the
service code available to date as it is still under development for STAR
and a new Tag Recommnder project just starting. However, we are
committed to publishing the server software as open source by the end of
the STAR project and anyone interested in collaborative API development
is welcome to contact me regarding an interim snapshot version. The
current version uses the SemWeb RDF library. 

Within the project, we've also been discussing the relative pros/cons of
a specialist SKOS web service vs a general RDF query language (SPARQL)
and would be interested in any wider discussion. 

Different conditions may favour the one or the other. A SPARQL endpoint
lets you do anything supported by SPARQL and does not restrict to the
specific services exposed. However it may be found that some
functionality is not easy/possible in SPARQL. A service API could be
implemented on top of SPARQL or via another platform and does not have
to be a web service, although web services offer a platform neutral
capability (potentially available as an external, third party service). 

Al (Dan) mentioned issues as to whether any API functionality might be
hard to realise efficiently in SPARQL, eg text-based query or iterative
cost-based concept expansion. Other reasons for a specialised API (or
program library) could be if some developers, making use of SKOS, prefer
not to be constrained to SPARQL for any reason (eg security issues in
exposing the database, skillset issues or existing platform
constraints), or if the API functions correspond to common use cases
that can be provided at a higher level. 


1. Background on KOS services and user interface patterns - 
Binding C., Tudhope D. 2004. KOS at your Service: Programmatic Access to
knowledge Organisation Systems. Journal of Digital Information, 4(4)

2. Concept based query expansion paper
Tudhope D., Binding C., Blocks D., Cunliffe D. 2006. Query expansion via
conceptual distance in thesaurus indexed collections. Journal of
Documentation, 62 (4), 509-533. Emerald.

3. STAR - Semantic Technologies for Archaeological Resources

Douglas Tudhope
Professor, Faculty of Advanced Technology
University of Glamorgan
Pontypridd CF37 1DL
Wales, UK
Tel +44 (0) 1443-483609
Fax +44 (0) 1443-482715
Editor : The New Review of Hypermedia and Multimedia

-----Original Message-----
From: public-esw-thes-request@w3.org
[mailto:public-esw-thes-request@w3.org] On Behalf Of Alistair Miles
Sent: 14 April 2009 12:47
To: Johan De Smedt
Cc: public-esw-thes@w3.org; public-swd-wg@w3.org
Subject: Re: SKOS API and web-service

hi johan

On Wed, Apr 08, 2009 at 08:42:32AM +0200, Johan De Smedt wrote:
> Dear,
> Following the new CR for SKOS,
> is there an update planned for
> http://www.w3.org/2001/sw/Europe/reports/thes/skosapi.html ?

no, this wasn't in scope for the swdwg. if folks would like to use
this list to discuss a community-led update to the skos web service
api that would be great.

i know doug tudhope and ceri binding at glamorgan have worked on this
fairly recently, they use concept expansion methods to support
information retrieval. 

adding to what dan said, the skos ws api was written before there was
sparql. it would be nice to look again at the skos ws api, in light of
sparql, and to ask which methods really add something over sparql,
either in terms of convenience or functionality. e.g. you can't do
cost-based expansions with sparql, at least not easily. you also can't
do very efficient text-based queries. some stuff you can do tho,
e.g. see [1].




> Thanks for information or advice.
> Kind Regards,
>    Johan De Smedt
> =================
> johan.de-smedt@tenforce.com
> mobile: +32 477 475 934
> =================

Alistair Miles
Senior Computing Officer
Image Bioinformatics Research Group
Department of Zoology
The Tinbergen Building
University of Oxford
South Parks Road
United Kingdom
Web: http://purl.org/net/aliman
Email: alistair.miles@zoo.ox.ac.uk
Tel: +44 (0)1865 281993
Received on Monday, 20 April 2009 17:48:17 UTC

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