wp-arc-1.1: new version

wp-arc bug fixes and improvements

HTML entities are now handled correctly and some extra code was included to remove the slashes automatically added to queries during form processing. The plugin can be viewed on my new blog. Just go to the “wp-arc demo” page and click on the submit button. Download wp-arc from here.

As an example, the following query will work when input as is, or after being run through an html entity encoder. You might like to try the entity encoder pointed to by this url.

PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX : <http://dbpedia.org/resource/>
PREFIX dbpedia2: <http://dbpedia.org/property/>
PREFIX dbpedia: <http://dbpedia.org/>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX dbo: <http://dbpedia.org/ontology/>

SELECT ?name ?birth ?death ?person WHERE {
?person dbpedia2:birthPlace
           <http://dbpedia.org/resource/Berlin> .
?person dbo:birthdate ?birth .
?person foaf:name ?name .
?person dbo:deathdate ?death
FILTER (?birth < "1900-01-01"^^xsd:date) .
}

Here are some example shortcode commands:

1) Shortcode command for form processing:

[sparql input='form']
[/sparql]

2) Shortcode command to query a SPARQL endpoint

[sparql input='inline' endpoint='http://dbpedia.org/sparql'
      display='name']
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX : <http://dbpedia.org/resource/>
PREFIX dbpedia2: <http://dbpedia.org/property/>
PREFIX dbpedia: <http://dbpedia.org/>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX dbo: <http://dbpedia.org/ontology/>

SELECT ?name ?birth ?death ?person WHERE {
?person dbpedia2:birthPlace
            <http://dbpedia.org/resource/Berlin> .
?person dbo:birthdate ?birth .
?person foaf:name ?name .
?person dbo:deathdate ?death
FILTER (?birth < "1900-01-01"^^xsd:date) .
}
[/sparql]

3) shortcode command to query an RDF file

[sparql input='file'
rdf='http://foafbuilder.qdos.com/people/
andrew.ritz.myopenid.com/foaf.rdf']
[/sparql]

WordPress plugin: wp-arc

While reading about SPARQL I developed a wordpress plugin (wp-arc) which I’ve decided to release into the public domain. The plugin implements a shortcode interface to the ARC RDF system. To use the plugin you’ll need to install my forms library first. Both plugins can be found here: wp-forms, wp-arc. The lastest verison, wp-arc-latest.zip, contains a few improvements. There was an extra line at the end of the old version of wp-arc.php, which may have caused compilation problems. Also the processing of HTML entities and backslashes has been improved. If you have any problems installing them please let me know because I’ve only tested them on my local installation running wordpress 2.7.1. The interface is minimal but OK for building on.

The shortcode command has four options:

• input = ”form”, “inline” or “file”
• endpoint = ”the SPARQL endpoint”
• rdf = “an rdf filename”
• display = “the query variable to display” – only one variable can be input at present

To display a form for inputing SPARQL queries just create a page containing the following shotcode with the input option set to ‘form’:

    [sparql input='form']
    [/sparql]

When the form loads you will be presented with a “submit” button and three text fields for inputting the “endpoint”, the “sparql query” and the “variable” to display.

If you don’t want to use the form interface then just input the same shortcode with the options shown below. The SPARQL query should be enclosed between the opening and closing shortcode tags.

[sparql input='inline' endpoint='http://dbpedia.org/sparql'
          display='name']
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX : <http://dbpedia.org/resource/>
PREFIX dbpedia2: <http://dbpedia.org/property/>
PREFIX dbpedia: <http://dbpedia.org/>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX dbo: <http://dbpedia.org/ontology/>

SELECT ?name ?birth ?death ?person WHERE {
     ?person dbpedia2:birthPlace <http://dbpedia.org/resource/Berlin> .
     ?person dbo:birthdate ?birth .
     ?person foaf:name ?name .

     ?person dbo:deathdate ?death
     FILTER (?birth < '1900-01-01'^^xsd:date) .
}
[/sparql]

The triples in an RDF file can be displayed by inputting the following shortcode and options.

    [sparql input='file' rdf='http://foafbuilder.qdos.com/people/andrew.ritz.myopenid.com/foaf.rdf']
    [/sparql]

Sorry about the lack of documentation for these plugins. I promise to rectify the situation when time permits. I also intend to increase the number of options.

One last thing, you may need to encode the HTML entities within your sparql queries that you quote with shorcode tags. You can do that here.

WordPress & Dokuwiki on a Slitaz LiveCD

You can download a Slitaz LiveCD with Dokuwiki and WordPress already installed from here. To get started just boot Slitaz and start Firefox. Once you have started Firefox you will find links to three of my favourite plugins for blog post enrichment.

Slitaz 2.0, Protégé and Prolog

This month’s LiveCD contains Protégé, Prolog and the PrologTab. Protégé is a nice lightweight tool for creating customised knowledge-based applications. The LiveCD contains one such application – a rule based system (RBS) for training assessment.

Get started by booting Slitaz from the LiveCD and logging in as ‘tux’ with no password. A brief description of the demo RBS can be found by viewing Dokuwiki’s start page. The fasted way to start Dokuwiki is by clicking on the Firefox icon at the bottom of the screen. The description of the system is rather terse but should suffice. To run the Protégé ontology editor and knowledge acquisition system just double click on the relevant desktop icon.

POPLOG V15.62 is also installed. These days I tend to use POLOG as a scripting language (POPSH) so the version I have shipped with the LiveCD is compiled without the XWindows system. To start POPLOG just click on the desktop item.

In summary the Slitaz LiveCD contains the following:

• Protégé
• PrologTab
• Demo RBS
• Dokuwiki
• POPLOG
• POPSH

April’s flavour was delayed slightly because I decided to switch to Slitaz 2.0 at the last minute.

SliTaz and the Semantic Web

Recently I’ve started to become interested in small linux distributions such as SliTaz, which boots from a CDROM or pendrive and resides in computer memory.

So far I’ve managed to port the following semantic web toolkits to SliTaz:

• Twinkle
• Protege
• RDF123
• ThManager
• JRDF
• Graphl
• GrOWL/OntoBrowser
• Kaon
• Smore
• Swoop
• Mulgara
• Swi Prolog
• POPLOG

Each month Langtech plans to release a LiveCD with a selection of these tools on. This month you can download a LiveCD containing the Redland RDF Libraries and Twinkle. The LiveCD can be downloaded from ifile

LiveCD: the Redland RDF libraries with a little twinkle

This month’s flavour is the SPARQL query language for searching RDF-based websites for semantic content. Information on the Semantic Web is stored in RDF files which can be converted into triples – SUBJECT PREDICATE OBJECT. With the tools on the LiveCD, you can extract all the triples in an RDF file and write SPARQL queries asking for specific information. For instance, “find me the names of all the elements in the periodic table”.

Two query tools are introduced for accessing the data in an RDF file. The first tool is called, ROQET, which is distributed with the Redland libraries. The second tool is called, TWINKLE, and is a GUI interface that wraps the ARQ sparql query engine. The tool for finding all the triples in an RDF file is called RAPPER. In addtion you will also find a tool called LQRAPS, for reconstructing RDF from tabular data.

The LiveCD can be downloaded from here. Once you have booted the LiveCD and logged in (username: hacker, no password), you should start firefox and read the contents of the start page.

In summary the LiveCD contains the following:

• The Redland RDF libraries
• TWINKLE
• LQRAPS
• Dokuwiki

If you have any queries do not hesitate to contact me (aemr@tlen.pl).

The Semantic Web and Change

Recently I’ve been reading a lot of articles about the failure of the semantic web. What intrigues me about such discussions is that not one of them addresses these issues:

* how/who transforms a large dynamic information network like the WWW into something else?
* how does one measure change on the web?
* over what timescale does/should change take place?

I would not like to answer these questions now, but just make a few comments.

A few years ago I was interested in the semantic web but did not spend too much time trying to use any of the emerging technologies myself. The main reason for this was that I did not have the computing power at my disposal. Over the years, as I read more about the web, I eventually decided to upgrade my computing facilities so that I could experiment with some of the available technologies. Now I’m in the position where I can use many of the available tools when building my own applications and also port them to, by today’s standards, moderate sized computer systems. This possibility has been brought about by the availability of tools such as VMware and small LINUX distributions which enable developers to explore the robustness and applicability of available software in a reasonable amount of time. Therefore from my point of view the Semantic Web is already here and I’m using it. In fact I’m making more use of web 3.0 technologies in my applications than I ever did of web 2.0. That’s because web 3.0 technologies allow me to seamlessly integrate the storage, transformation and display of data.

Before I could change the way I worked there had to be alternatives. Surely that is what the web is about. Unless alternatives exist change will never happen. At present the semantic web is the only real alternative for future development. If there are others I’m not aware of them. I chose to start using Semantic Web Technologies and I’m sure that lots of others will follow. Individual users have a lot of power on the web but it takes a long time for users to mobilize their resources and effect change. Also without a well defined set of development alternatives change is not possible. Therefore the Semantic Web is a success because it does present people like myself with a real alternative which makes computational sense.

One result of my explorations into Semantic Web Technologies are the LiveCDs that I will be releasing every month. These CDs are designed to demonstrate a particular aspect of Semantic Web Technologies. This month you can download SLiTaz/POPLOG, a multi language programming environment which I’ve been using for years and quite like. While, POPLOG, does not come with any Semantic Web Tools, it does come with PROLOG, POP11 and a foreign function interface. I plan to use POPLOG to develop a high level language interface to the Redland libraries.

The semantic web may not be the future of the web but at present it is the only coherent development path that I’m aware of and for that I’m very grateful.

Semantic Web Languages

The second webinar, transmitted by Semantic Universe, finally got underway after some production problems. This seminar gave a nice overview of RDF, RDFS and OWL. The event recording can be found here.

Why are we here?

I’ve just finished listening to a webinar hosted by Eric Franzon and given by James Hendler (Rensselaer Polytechnic Institute) and Dean Allemang (TopQuadrant). The Webinar focussed primarily on the uses of the semantic web and as a result touched on database technology. I enjoyed the talk which was at just the right level for me because I’m not a database guy and try to avoid them as much as possible. Now I know that an RDF triple store will help me do the latter I like the semantic web even more! For more information about future seminars and event recordings visit this site.

Semantic Wave 2008 Report

A 31 page executive summary of the “Semantic Wave Report” is available for download. The report is published by Project10X and is purported to be a comprehensive, ground-breaking 400 page study of semantic technologies and their market impact.