Advanced Semantic Technologies Project: S2S Publication
Eric Rozell*
Tetherless World Constellation, Rensselaer Polytechnic Institute, Troy, New York, USA
AST_2011_Rozell_Eric_Week6
ABSTRACT
During Summer 2010, I researched at Woods Hole Oceanographic Institution (WHOI) under the Summer Student Fellowship Program. My project involved the design and implementation of a customizable and extensible dashboard
interface for searching and analyzing various kinds of
oceanographic data. The outcome of the project was S2S, a
web application and framework for building advanced search
interfaces for web services described by semantic annotations. During the Advanced Semantic Technologies class, I
plan to write up a publication for submission to the Earth
Science Informatics journal about this project.
1
PROJECT SUMMARY
During my summer fellowship, I worked closely with
oceanographers, data managers, and IT specialists at WHOI
in the development of a dashboard interface for searching
and analyzing oceanographic data. Interviews with oceanographers were used to develop scientific use cases that
would refine the scope of the summer project and to establish reputable resources for oceanographic data on the Web.
Interviews with data managers were held to learn more
about data services at WHOI, and to identify a project that
would be useful to the data management community.
Oceanographers identified the potential utility of a uniform
interface for searching over data across oceanographic disciplines, claiming that they were often unaware of reputable
sources outside their own disciplines, and experienced a
learning curve when they found and needed access to such
sources. Data managers identified the need to develop
standardized web services, but noted that there was little
internal benefit to such practices, other than visibility in a
larger project or web portal. S2S was designed to suit the
needs of the broad oceanographic community, including
both scientists and data managers.
Oceanography covers a broad range of scientific disciplines (e.g., physics, chemistry, biology, engineering), and
as such the data products found throughout the domain are
highly heterogeneous. Thus, identifying a metadata model
that suited the broad needs of the oceanographic community
was beyond the scope of a summer project. Rather, S2S
*
takes a service-oriented approach. S2S uses the Resource
Description Framework (RDF) and the OWL Web Ontology
Language to organize metadata about web services and user
interface components. The purpose of these semantics is to
enable community development from different perspectives
(i.e., scientists’, service developers’, and user interface developers’), and to support a greater degree of extensibility
and customizability than traditional object-oriented approaches. S2S can be used to search and analyze data from
web services that comply with select web service standards
supporting semantic annotation (e.g., OpenSearch,
SAWSDL) and also SPARQL-enabled services. Search and
analysis tools for S2S can be created and stored at distributed locations on the Web.
2
HOW IT WORKS
There are two primary components to the S2S framework:
the S2S ontology and knowledge base, and the S2S server.
The S2S ontology and (potentially distributed) knowledge
base contains information relevant to the discovery of web
services and user interface components. Scientists can use
the contextual metadata provided by the knowledge base to
assist in their selection of a web service. Scientists can also
interchange user interface components based on usability
preferences or prior experience (i.e., they can customize the
interface). The ontology model associates user interface
components with particular service output formats and
search parameters they support, so that components can be
reused across a variety of services.
As an example, in oceanography, a geographic bounding
box is a commonplace search parameter used across many
data services. A user interface developer could design a
map “widget” that could be used to enable bounding box
input. This semantic metadata for the map widget would
associate it to the geo:box search parameter (a URI representative of a geographic bounding box input). Thus, when
a search interface for a particular web service is being constructed, when it is detected that the service uses the
geo:box parameter, the user would be presented with the
choice to use the map widget, among other user interface
components that support searching over the geo:box parameter.
To whom correspondence should be addressed.
1
Rozell, E.
The second component to the S2S framework is the S2S
server. The server handles requests for metadata from the
knowledge base and acts as a proxy to distributed web services. The S2S server has an object-oriented interface for
accessing information about web services that need not (or
cannot) be encoded within the knowledge base (e.g., information that is represented in an XML document such as a
SAWSDL, or OpenSearch description document). To enable a web service standard, a PHP class can be created that
implements the S2S search service interface and extracts
important information from the web service or its description.
The intent of the framework is to support the development
of web portals for federating search across standard web
services and to enable the development of customizable,
extensible uniform interfaces. A prototype web application
has been built for searching OpenSearch services using
jQuery.
3
ADVANCED SEMANTIC TECHNOLOGIES
PROJECT
The overall design of S2S is starting to converge, and, as
such, I would like to use the Advanced Semantic Technologies class to write a paper summarizing the current results. I
plan to submit to the Earth Science Informatics journal, and
there are two alternatives to the kind of paper I could write,
a research paper and a methodology paper.
3.1
Research Paper
In order to write a research paper I have to come up with a
research question that is addressed by the S2S application
and framework. Following the methods of The Craft of
Research, I need to identify a research topic and research
question. The research problem that will be used to answer
the question, of course, would be to design and implement
S2S.
The topic I originally set out to work in was data integration, but as I started designing use cases, I discovered that I
was mostly interested in web service and application integration due to the diversity of data products in oceanography. Thus, my research topic of interest is data and application integration.
I had planned from the beginning of the project to apply
Semantic Web technologies. Since I was working primarily
at the web service layer, and I was aware of existing approaches to apply semantics in the description of web services, I chose to apply Semantic Web technologies for the
development of a data and application integration framework. Alternatively, I could have used solely objectoriented programming techniques in the implementation of
the framework. Thus, the potential research question that
I’ve identified is: “Can employing Semantic Web technologies in the implementation of a web application framework
2
AST_2011_Rozell_Eric_Week6
provide additional flexibility beyond a traditional objectoriented approach?” I think the research answer here is yes;
using Semantic Web technologies can enable the development of web application frameworks that take advantage of
the distributed nature of the web. Rather than requiring a
centralized code repository for all framework components,
framework component metadata can be encoded in RDF and
placed anywhere on the Web. The semantics of the application framework can be encoded using OWL, and the framework components can link to each other using these semantics.
3.2
Methodology Paper
Alternatively, this paper can be written as a methodology
paper. As Prof. McGuinness stated, methodology papers
are not usually considered as significant as research papers,
but this work does present an interesting combination of two
methodologies for web systems development. One of these
methodologies is the Semantic Web Methodology & Technology Development Process, which has been used extensively by Prof. McGuinness and Prof. Fox in the design and
implementation of virtual observatories and eSciencerelated projects. The other methodology is that of Steve
Lerner and Andrew Maffei in developing interfaces for heterogeneous oceanographic data, including imagery and realtime data, and designing reusable software. This paper
would focus mostly on the details of implementing S2S and
how these two methodologies were successfully combined.