Databases Reference
In-Depth Information
Pingback-enabled resource is mentioned (i. e. linked to) by another party, its pingback
server is notified of the usage. Provided, the Semantic Pingback extension is enabled
all resources used in OntoWiki are pinged automatically and all resources defined in
OntoWiki are Pingback-enabled.
4.6
Exploration Interfaces
For exploring semantic content, OntoWiki provides several exploration interfaces that
range from generic views over search interfaces to sophisticated querying capabilities
for more RDF-knowledgable users. The subsequent paragraphs give an overview of
each of them.
Knowledge base as an information map.
The compromise between, on the one hand,
providing a generic user interface for arbitrary RDF knowledge bases and, on the other
hand, aiming at being as intuitive as possible is tackled by regarding knowledge bases
as
information maps
. Each node at the information map, i. e. RDF resource, is repre-
sented as a Web accessible page and interlinked to related digital resources. These Web
pages representing nodes in the information map are divided into three parts: a left side-
bar, a main content section and a right sidebar. The left sidebar o
ers the selection of
content to display in the main content section. Selection opportunities include the set of
available knowledge bases, a hierarchical browser and a full-text search.
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Full-text search.
The full-text search makes use of special indexes (mapped to propri-
etary extensions to the SPARQL syntax) if the underlying knowledge store provides
this feature, else, plain SPARQL string matching is used. In both cases, the resulting
SPARQL query is stored as an object which can later be modified (e. g. have its filter
clauses refined). Thus, full-text search is seamlessly integrated with faceted browsing
(see below).
Content specific browsing interfaces.
For domain-specific use cases, OntoWiki pro-
vides an easy-to-use extension interface that enables the integration of custom compo-
nents. By providing such a custom view, it is even possible to hide completely the fact
that an RDF knowledge base is worked on. This permits OntoWiki to be used as a data-
entry frontend for users with a less profound knowledge of Semantic Web technologies.
Faceted-browsing.
Via its faceted browsing, OntoWiki allows the construction of
complex concept definitions, with a pre-defined class as a starting point by means of
property value restrictions. These two views are su
cient for browsing and editing all
information contained in a knowledge base in a generic way.
Query-builder.
OntoWiki serves as a SPARQL endpoint, however, it quickly turned out
that formulating SPARQL queries is too tedious for end users. In order to simplify the
creation of queries, we developed the
Visual Query Builder
9
(VQB) as an OntoWiki
extension, which is implemented in JavaScript and communicates with the triple store
