What
is the OpenLink Data Explorer Extension?
The
OpenLink Data Explorer
is a browser extension (currently available for Firefox with
additional browser support to follow) that adds a new option to the Web User Agent functionality realm in
the form of new main and context menu options for viewing Data Sources associated with Web Pages.
Why is the OpenLink Data Explorer Extension Important?
It allows Web users to explore the raw data and data relationships that underly a Web page.
The extension enables users to switch between Hypertext
and Hyperdata link traversal of Web data.
What is Linked Data?
The term "Linked Data", coined by Tim
Berners-Lee in a 2006 Design Issue note, describes an entity level
"Data
Access by Reference" mechanism for the Web, courtesy of dereferenceable URIs.
Why is Linked Data Important?
It provides direct access to the raw data entities within (or behind) Web pages; thereby enabling the construction of powerful "data meshups" across heterogeneous data source collections, without any programming.
How Does Linked Data Work?
By incorporating HTTP into the resource naming schemes of Web accessible resources, so that the same linking mechanism used for retrieving a Web Page (and other information resources) also extends to the process of retrieving a structured description of a resource. This process is quite similar to accessing a SQL
recordset via an ODBC or JDBC data source name (DSN). The fundamental differences between Linked Data and SQL CLI based data access are:
- Linked Data URIs name / identify individual records while SQL data access DSNs are scoped to record containers such as Database, Table, View, or Stored Procedure names
- Linked Data URIs facilitate untethered data access that transcends database vendor, database engine, operating system, programming language, application server, application development framework, and other infrastructural confines, unlike ODBC, JDBC, and other data access mechanisms.
The illustration below, highlights Linked Data's parallels with ODBC in relation to DSN based data access.
What is the Linked Data Web?
An evolution of the Web that places you a click away from a structured description of any Web accessible resource. A more granular Web where interaction focus moves away
from opaque compound documents to the entities they host.
What is the Linked Data Cloud?
As illustrated below, it's the moniker for the growing collection of Linked Data sources being injected into the Web by the Linking Open Data Community.
Each node in the above cloud represents a domain of knowledge or realm of information. Some are collections housed entirely within a
given site or service; others are formats used by many sites or services. As shown by the arrows, each is explicitly interlinked with at least one
other node in the cloud. More nodes and more links are being added all the time, leading to longer chains of interconnectedness, which in turn
lead to more discoveries of unexpected and interesting relationships.
There are several paths to materialized Linked Data.
- "On the fly" generation via RDF middleware, from
- Enterprise Data Sources, such as:
- Community Driven Extraction Efforts, such as:
Why is the Linked Data Web Important?
By providing bridges between areas of interest and knowledge, the Linked Data Web can reveal relationships where information
might otherwise be seen as unrelated. For instance, one might explore which industry and government leaders had previously been
classmates or were somehow connected by family.
The OpenLink Data Explorer enables a user to browse from one "thing" to another just as easily as they would click from one
page to another with standard hyperlinked document browsing, but with greater understanding and comprehension from the first click.
How can the OpenLink Data Explorer Extension help me exploit the Linked Data Web?
The best way to learn how this extension can help you is to install it, and follow along with the examples below. If you decide you can't
benefit by exploiting the Linked Data Web in this way, you can un-install the extension without harm.
Download
The OpenLink Data Explorer can be downloaded from one of the following locations
Installation
The loading of the OpenLink Data Explorer tool differs slightly depending on which method was using to download it.
- From the Mozilla Add-ons site, click on "Add to Firefox", Firefox will then install the Extension as an "Add-on".
- From the OpenLink Web Site, download the "ode.xpi" file and load from the "Open File" menu item of the Firefox "File" menu.
- From the Amazon S3 Storage Site, you will immediately be presented with the option to install the ODE add-on.
- From the Softpedia Web Site, download the "ode.xpi" file and load from the "Open File" menu item of the Firefox "File" menu.
The OpenLink Data Explorer Firefox Add-ons installation dialog will then be presented.
You will need to restart Firefox after it has finished installing.
Once it has finished restarting, you should see the extension in your add-ons list.
Configuration
To reach the preferences panel for the OpenLink Data Explorer Extension. Go to the "Tools" menu and
Click on "Add-ons". Then select "OpenLink Data Explorer" and click on the "Preferences" button.
There are two tabs for configuration:
- The "Viewers" tab
- The "RDF Services" tab
The Viewers Tab
The default "Viewer" option has the benefit of being built into the Browser Extension, and therefore provides
the smoothest browsing experience. It is possible to modify the RDF Browser (Viewer) and
SPARQL
Endpoint to use any available server which has the right capabilities. The image below shows the default
configuration which uses the OpenLink Data Explorer viewer hosted on the demo.openlinksw.com server.
A list of supported viewers is displayed in the "Viewer" drop down list box as shown below:
The Virtuoso default "SPARQL Endpoint" or a custom endpoint of the form "http://demo.openlinksw.com/sparql?query=" can be chosen from the drop down list box as indicated below:
The RDF Services Tab
The RDF Services tab is used for specifying the location of the RDF sponger cartridges to used for sponging the RDF available data from the request URL,
and by default uses the Virtuoso sponger cartridges hosted on the demo.openlinksw.com server or this can be changed to use a Virtuoso instance of ones choice
where the require sponger cartridges are loaded, as indicated in the diagram below:
The "RDFizer Service" drop down list box contains the entries below of supported RDF services that can be used for sponging data:
-
OpenLink Virtuoso (Sponger) - default sponger method used by the OpenLink Data Explorer
-
OpenLink Virtuoso (Sponger - Simple) - Alternative REST service that has similar pattern to Triplr.
-
Triplr
-
"Custom URL" of the form "
http://server:port/proxy?url="
Use
The steps to use the OpenLink Data Explorer are simple
- Open any web document
- Send it through to the OpenLink Data Explorer, either by:
- Under the View Menu in Firefox, click "View Linked Data Sources".
- Right-Click (or Ctrl-Click on Mac) the page or a link, then click "View Linked Data Sources".
- An OpenLink Data Explorer interface will load in a new tab and you will be able to seamlessly
browse through the Linked Data Web.
The examples page walks through some of the options and
functionalities of the OpenLink Data Explorer.