Terse RDF Triple Language (Turtle)

RDF is a general-purpose declarative language (based on XML) for representing information such as resources or entities on the web.

Proposed by Tim Berners-Lee and David Beckett, the Turtle syntax is aimed at providing a compact and more human-readable notation for RDF. It adds shorthand notation for common patterns and datatypes as well as being compatible with SPARQL syntax — actually SPARQL query syntax for WHERE clauses is very similar to Turtle.

All RDF written in Turtle should be usable inside SPARQL which uses a Turtle syntax for building RDF graphs in its CONSTRUCT clause.

Now we present a brief syntax summary:

In  Turtle, there are 3 types of RDF Terms: RDF URI References, literlas, and blank nodes.

A RDF term is a URI enclosed in brackets. For example:

<http://example.org/path/#fragment>

These are typically abbreviated using Turtle’s @prefix tag.

Literals are written in double quotes as such: “Mary” or “Daisy”. Alternatively, you can wrap the literal in ” ” ” long lone ” ” ” to indicate that the literal might contain line breaks. In addition, you can give literals a language suffix: “Disney World”@en or “El Mundo Disney”@es.

Blank nodes are written as _nodeId: or can also be made with [ ].

Comments in Turtle are created using the hash (#) symbol.

Every complete triple has a dot (.) at the end. A semi colon (;) is valid when the original subject is reused for two or more triples. A comma (,) can be used when reusing a common subject and predicate.

The following is an example Turtle document:

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix dc: <http://purl.org/dc/elements/1.1/> .
@prefix ex: <http://example.org/stuff/1.0/> .

<http://www.w3.org/TR/rdf-syntax-grammar>
  dc:title "RDF/XML Syntax Specification (Revised)" ;
  ex:editor [
    ex:fullname "Dave Beckett";
    ex:homePage <http://purl.org/net/dajobe/>
  ] .

Resources:

1. http://www.w3.org/TeamSubmission/turtle/

RDFa

RDFa stands for Resource Description Framework-in attributes and provides a set of XHTML attributes to enhance visual data with machine-readable hints. This standard originates to tackle today’s web which has been built predominantly for human consumption. Even as machine-readable data begins to appear on the web, it is typically distributed in a separate file, with a separate format, and very limited correspondence between the human and machine versions. As a result, web browsers can provide only minimal assistance to humans in parsing and processing web data: browsers only see presentation information.

With RDFa we can embed rich metadata within XHTML documents. This metadata has the form of RDF triples User-Predicate-Object. Some examples of RDFa attributes are the following:

  • about and src – a URI or curie specifying the resource the metadata is about
  • rel and rev – specifying a relationship or reverse-relationship with another resource
  • href and resource – specifying the partner resource
  • property – specifying a property for the content of an element
  • content – optional attribute that overrides the content of the element when using the property attribute
  • datatype – optional attribute that specifies the datatype of text specified for use with the property attribute
  • typeof – optional attribute that specifies the RDF type(s) of the subject (the resource that the metadata is about).

Users can easily combine there attributres with other schemas such as FOAF into web pages in order to build rich compelling social sites. For example,  an event on a web page can be directly imported into a user’s desktop calendar.  A photo’s creator, camera setting information, resolution, and topic can be published as easily as the original photo itself, enabling structured search and sharing. Geo location can be embedded so that users can easily track authors of articles.

RDFa has demonstrate quite an impressive growth in recent years. New research released by Yahoo! shows that RDFa demonstrated explosive growth in 2010 as the  fastest growing data markup format on the Web, and is used on more than 430 million web pages. It accounts for roughly 3.6% of the all of the Web pages on the Internet. How much did RDFa grow last year? 510% .

Resources:

1. http://rdfa.info/

2. http://www.w3.org/TR/xhtml-rdfa-scenarios/

3. http://en.wikipedia.org/wiki/RDFa

Using WADE in Eclipse using WOLF Plugin

WADE is a software platform based on JADE that provides support for the execution of tasks defined according to the workflow metaphor. The key component of the WADE platform is the WorkflowEngineAgent class that extends the basic Agent class of the JADE library embedding a small and lightweight workflow engine. Besides normal JADE behaviours, a WorkflowEngineAgent is therefore able to execute workflows represented according to a WADE specific formalism. This formalism is based on the Java language: a WADE workflow is actually a Java class with a well defined structure. This approach makes it possible to combine the expressiveness of the workflow metaphor with the power of a programming language such as Java, and enables the usage of workflows for system internal logics definition.

In principle WADE supports “notepad-programming” in the sense that there is no hidden stuff that developers can’t control. However, especially considering that one of the main advantages of the workflow approach is the possibility of representing processes in a friendly graphical form, WADE comes with a development environment called WOLF that facilitates the creation of WADE-based application. WOLF is an Eclipse plug-in and as a consequence allows WADE developers to exploit the full power of the Eclipse IDE plus additional WADE-specific features.

Go to the WADE Website to Download WADE & WOLF

To install WOLF in Eclipse…. download the zip files for the plugin to your local system.

You must register before you can download the files, if you already registered to download JADE you can use that account to login.

Extract the contents of the zip files into the Eclipse plugin directory where you installed Eclipse on your system. (Make sure to extract the actual plugin in the plugin folder of the zip file to the plugin folder inside of eclipse.) This needs to be done as a manual installation according to the instructions for installing WADE

Read Chapter 1.1: WADE Installation Tutorial or see below

WOLF
As mentioned WOLF is an Eclipse plugin and therefore it is necessary to have Eclipse version 3.3 (Europa) or later already installed. Actually versione 3.4 is suggested as it fixes some bugs that may create annoying problems when using WOLF. Furthermore WOLF makes use of the GEF (Graphical Editing Framework) plugin for graphic rendering version 3.3 or later that must be
installed too. Both Eclipse and GEF can be downloaded from the Eclipse website at http://www.eclipse.org.
At this point the easiest way to install WOLF is unzipping the WOLF distribution zip file (available for download from the WADE website at http://jade.tilab.com/wade) into the Eclipse home directory. Refer to the Eclipse documentation for more details about plugins installation.
If a previous version of WOLF is already installed, it is necessary to remove it from the Eclipse plugins directory (by simply deleting the subdirectory related to WOLF) before installing the new one. Both WADE and WOLF require Java 5 or later.

Additional  articles related to WADE:

Read about WADE: A software platform to develop mission critical applications exploiting agents and workflows

Read more about WADE and how it works

Open Graph Protocol

The Open Graph Protocol (hereafter just OGP) enables a web site to display rich content in a social graph. This is a very simple but powerful concept, one which sites like Facebook have pioneered and leveraged extensively.

In order for a web site to become part of a social graph, you must add a set of meta data to the page. The protocol implemented relies on RDFa. RDF is the Resource Description Framework, and it is basically a language for modeling different optimized for sharing and interchange of information. RDFa simply adds a set of extra attributes to the XHTML standard in order to support the extra meta needed for OGP.

Basic Metadata

  • og:title : The title of your object as it should appear within the graph.
  • og:type : The type of your object, e.g., “movie”. Depending on the type you specify, other properties may also be required.
  • og:image : An image URL which should represent your object within the graph.
  • og:url : The canonical URL of your object that will be used as its permanent ID in the graph.

With this basic information, your web site can be mapped in a social graph. In addition, there are other types of meta you can add including: location, audio, video, etc.

  • og:latitude – e.g., “37.416343″.
  • og:longitude – e.g., “-122.153013″.

If you wish to specify a human readable address, include the following five properties:

  • og:street-address – e.g., “1601 S California Ave”
  • og:locality – e.g, “Palo Alto”
  • og:region – e.g., “CA”
  • og:postal-code e.g., “94304″
  • og:country-name – e.g., “USA”

After you add all of the meta data of your choice, you can visit: http://www.opengraph.in/ and see how your site was parsed. Go ahead and try it with this site!

Resources:

1. http://ogp.me/
2. http://www.opengraph.in/

Stay Tuned! visit http://reflectivethought.net

SQLite Database Browser

SQLite Database Browser Website

What it is

SQLite Database Browser is a freeware, public domain, open source visual tool used to create, design and edit database files compatible with SQLite. It is meant to be used for users and developers that want to create databases, edit and search data using a familiar spreadsheet-like interface, without the need to learn complicated SQL commands. Controls and wizards are available for users to:

  • Create and compact database files
  • Create, define, modify and delete tables
  • Create, define and delete indexes
  • Browse, edit, add and delete records
  • Search records
  • Import and export records as text
  • Import and export tables from/to CSV files
  • Import and export databases from/to SQL dump files
  • Issue SQL queries and inspect the results
  • Examine a log of all SQL commands issued by the application

You can download the SQLite Database Browser Click here to download

JADE (Java Agent DEvelopment Framework)

JADE (Java Agent DEvelopment Framework) is a software Framework fully implemented in Java language. It simplifies the implementation of multi-agent systems through a middle-ware that complies with the FIPA specifications and through a set of graphical tools that supports the debugging and deployment phases. The agent platform can be distributed across machines (which not even need to share the same OS) and the configuration can be controlled via a remote GUI. The configuration can be even changed at run-time by moving agents from one machine to another one, as and when required. JADE is completely implemented in Java language and the minimal system requirement is the version 1.4 of JAVA (the run time environment or the JDK).

The synergy between the JADE platform and the LEAP libraries allows to obtain a FIPA-compliant agent platform with reduced footprint and compatibility with mobile Java environments down to J2ME-CLDC MIDP 1.0. The LEAP libraries have been developed with the collaboration of the LEAP project and can be downloaded as an add-on of JADE from this same Web site.

JADE is free software and is distributed by Telecom Italia, the copyright holder, in open source software under the terms of the LGPL ( Lesser General Public License Version 2). Since May 2003, a JADE Board has been created that supervisions the management of the JADE Project. Currently the JADE Board lists 5members: Telecom Italia, Motorola, Whitestein Technologies AG, Profactor GmbH, and France Telecom R&D.

The latest version of JADE is JADE 4.0.1 released on 07/07/2010

You must register first to download JADE here http://jade.tilab.com/

Semantic Radar for Firefox

Semantic Radar is a semantic metadata detector for Mozilla Firefox.

Available at Mozilla Add-ons site. It is a browser extension which inspects web pages for links to Semantic Web metadata and informs about presence of it by showing an icon in browser’s status bar. Currently it supports RDF autodiscovery (SIOC, FOAF, DOAP and any type) and RDFa metadata detection.

New: Semantic Radar can now ping the Semantic Web Ping Service when metadata are detected. This allows for a community based discovery of the Semantic Web data.



Jena – A Semantic Web Framework for Java

Jena is a Java framework for building Semantic Web applications. It provides a programmatic environment for RDF, RDFS and OWL, SPARQL and includes a rule-based inference engine.

Jena is open source and grown out of work with the HP Labs Semantic Web Programme.

The Jena Framework includes:

  • A RDF API
  • Reading and writing RDF in RDF/XML, N3 and N-Triples
  • An OWL API
  • In-memory and persistent storage
  • SPARQL query engine

Support is provided by the jena-users mailing list.

FAU Semantic Web Course

Welcome to the FAU Semantic Web Course Website. This is where we will be posting materials and tutorials from our class. Please check back often as we will be updating the website on a regular basis with new information and examples.