Tag Archives: lod2stack

Virtuoso and LODRefine – more vicious than virtuous pair (part 2)

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First…

there was a big black hole (BBH). And then it got bigger. Seriously. At this point in my life I realized that more I learn more is there to learn.

Failure is success if we live to learn from it.
(Malcolm Forbes and me)

Second…

Chewing through the virtuoso documentation made me realize that using /sparql endpoint for updating graphs (i.e. inserting triples into it) is not  a particularly good idea. One has to have some security, right? I said to the SPARQL user that it has the right to return error on any non-SELECT demand. I found out that there are three possibilities of securing your virtuoso endpoint:

There is good news…

Implementing  digest authentication into LODRefine was easy peasy (after I found the right library that is). I used Apache HTTP Client for this:


...
import org.apache.http.client.params.AuthPolicy;
import org.apache.http.NameValuePair;
import org.apache.http.auth.AuthScope;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.auth.UsernamePasswordCredentials;
...
...
...
  DefaultHttpClient client = new DefaultHttpClient();
  client.getCredentialsProvider().setCredentials(
	new AuthScope(endpoint.getHost(),endpoint.getPort()),
		      new UsernamePasswordCredentials(properties.get("username"), properties.get("password"))
		     );
  client.getParams().setParameter(AuthPNames.PROXY_AUTH_PREF, AuthPolicy.DIGEST);
  HttpPost httpPost = new HttpPost(endpoint.toURI());  try {
        List  nvps = new ArrayList ();
        nvps.add(new BasicNameValuePair("query", query));
        httpPost.setEntity(new UrlEncodedFormEntity(nvps));
        HttpResponse response = client.execute(httpPost);
        ...
      }
  ...
  ...

Nice and simple, if only the virtuoso endpoint you are trying to use supports this kind of authentication – if it does, it is accessible at /sparql-auth. I had to enable it on my local virtuoso instance. I also created a new user with SPARQL UPDATE rights. For more details see Virtuoso guide.

… and there is oh-not-so-good news …

In LOD2 we decided to use WebID authentication. This will definitely not be a walk in the park. You’ll have to wait for part 3 to see, whether I survived this dangerous endeavor.

Avoiding danger is no safer in the long run than outright exposure. The fearful are caught as often as the bold. Especially if they don’t run fast enough.
(Hellen Keller and me)

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2nd release of LOD2 technology stack

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LOD2 project consortium announced new LOD2 technology stack release – a set of free tools, services and activities  serving one common purpose: creating knowledge out of interlinked data.

Linked Open Data Lifecycle

Linked Open Data Lifecycle (Photo credit: haschek)

The project coordinator Dr. Sören Auer states that “in a world of an emerging new data economy innovative and scalable mechanisms and technologies are needed to solve the arising data management problems – we see that lots of organisations are seeking for state-of-the-art data publishing and integration technologies along the whole data value chain to be able to efficiently use this growing amount of data. The efficient handling of data – available inside of organisations as well as on the internet – becomes more and more important to reach competitive advantage.”

LOD2 tool stack at your service: supporting every step in the Linked Open Data Lifecycle.

This 2nd release of the stack contains updates to the components:

  • Ontowiki,
  • Silk,
  • SigmaEE and
  • Virtuoso,

but also some new components:

  • SPARQLED (by DERI),
  • LOD enabled OpenRefine (by Zemanta),
  • extended version of Silk (University of Mannheim) with link suggestion management from LATC (by DERI),
  • rdfAuthor library (by ULEI) and
  • SPARQLPROXY (by ULEI)

LOD2 stack is organized as a Debian package repository and can be relatively easy installed on any Debian-based system (yes, Ubuntu is one of them) or you can try it in an online demo or experiment with it on a virtual machine (you’ll need free VMware player).  In case you need some help with installation, you can also check How-to document with more details and instructions.

Hold on, there’s more.

Next webinar is all about this 2nd release of the LOD2 Stack on December 12, 2012 at 4pm CET. More information and registration are available here.
Join us and the may the LOD force will be with you.

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Exploring the land of links: meet LIMES in the next LOD2 webinar

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It’s been a while since I last posted about LOD2. This doesn’t mean nothing is going on… on the contrary! We are working hard to make a life LOD users a bit easier. I could go on and on about this, but I won’t… not yet. This time I’d like to announce the 5th free LOD2 webinar about the tools in LOD2 Stack. Missed previous ones? You can find info about them on the LOD webpage.

Interested? Continue reading (the official text).

——

LOD2 Webinar: LIMES

The 1st version of the LOD2 Stack has been published in September 2011 in the form of a LOD2 Stack demo and the downloadable LOD2 Stack virtual machine image – additional details and the instructions on installing the LOD2 Stack from scratch are available in the HOWTO Start document.
Born from the wish to make linking tractable, the (LIMES) is tailored towards the time-efficient and lossless discovery of links across knowledge bases. LIMES is an extensible declarative framework that encapsulates manifold algorithms dedicated to the processing of structured data of any sort. Built with extensibility and easy integration in mind, LIMES allows implementing applications that integrate, consume and/or generate Linked Data. Within LOD2, it will be used for discovering links between knowledge bases.

LIMES dashboard (image from their official page)

This webinar will be presented by the LOD2 Partner: University of Leipzig (ULEI), Germany.
The LOD2 webinar series is powered by the LOD2 project organised and produced by the Semantic Web Company(Austria). If you are interested in Linked (Open) Data principles and mechanisms, LOD tools & services and concrete use cases that can be realised using LOD then join us in the LOD2 webinar series! The LOD2 team is looking forward to meeting you at the webinar!!

When : 27.03. 2012, 04.00pm – 05.00pm CET
Information & Registration: https://www2.gotomeeting.com/register/369667514
The LOD2 team is looking forward to meeting you at the webinar!!
——

About the LOD2 Stack

The LOD2 stack is an integrated distribution of aligned tools which support the life-cycle of Linked Data from extraction, authoring/creation over enrichment, interlinking, fusing to visualization and maintenance. The stack comprises new and substantially extended existing tools from the LOD2 partners and third parties. The LOD2 stack is organized as a Debian package repository making the tool stack easy to install on any Debian-based system (e.g. Ubuntu). The first release of the LOD2 stack contains the following components (available as Debian packages):

  • LOD2 demonstrator, the root package (LOD2)
  • Virtuoso, RDF storage and data management platform (Openlink)
  • OntoWiki, semantic data wiki authoring tool (ULEI)
  • Silk, interlinking engine (FUB)
  • D2R, RDF wrapper for SQL databases (FUB)
  • ORE, ontology repair and enrichment toolkit (ULEI)

As online services were integrated into the LOD2 Stack: PoolParty (taxonomy manager by SWCG) and Spotlight (annotating texts w.r.t. DBpedia by FUB). The LOD2 Stack also makes use of dataset metadata repositories such as thedatahub.org and http://publicdata.eu. A selection of the datasets has been packaged and are available in the LOD2 stack repository.
The LOD2 stack is an open platform for Linked Data components. We are happy to welcome new components. Detailed instructions how to integrate your component into the LOD2 Stack as Debian package are available in the HOW-TO-CONTRIBUTE. For assistance or any questions related to the LOD2-stack contact support-stack@lod2.eu. From now on we will regularly release improved and extended versions of the LOD2 Stack. Major releases are expected for Fall 2012 and 2013.

More information about the LOD2 Stack
Demo: http://demo.lod2.eu/lod2demo
Virtual Machine Image: http://stack.lod2.eu/VirtualMachines/
How To Document: How to Start.

What’s next – the LOD2 webinar series

The LOD2 webinar series offers several (one per month) free webinars about Linked Open Data tools and services around the LOD2 project, the LOD2 Stack and the Linked Open Data Life Cycle, also in the form of 3rd party tools.
The next 2 dates of the LOD2 webinar series are already fixed as follows:

About LOD2 – Creating Knowledge out of Interlinked Data
LOD2 is a large-scale integrating project co-funded by the European Commission within the FP7 Information and Communication Technologies Work Programme (Grant Agreement No. 257943). Commencing in September 2010, this 4-year project comprises leading Linked Open Data technology researchers, companies, and service providers (15 partners) from across 11 European countries (and 1 associated partner from KOREA) and is coordinated by the AKSW research group at the University of Leipzig, Germany.
LOD2 will integrate and syndicate linked data with large-scale, existing applications and showcase the benefits in the three application scenarios of media and publishing, corporate data intranets and eGovernment. The resulting tools, methods and data sets have the potential to change the Web as we know it today.
More information about LOD2
Web: http://lod2.eu
Blog: http://blog.lod2.eu
Slideshare: http://www.slideshare.net/lod2project
Twitter: @lod2project , #lod2
flickR: http://www.flickr.com/photos/lod2/

 

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What has LOD2 to do with OntoWiki … and me?

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English: The following diagram visualizes the ...

Image via Wikipedia

It is time to announce (another) webinar from LOD2 webinar series, this time about OntoWiki.

But first things first…

In September last year I joined Zemanta (allright!) as a researcher… and Zemanta is a partner in a FP7 project called Linked Open Data 2 – Creating Knowledge out of interlinked Data. I already wrote about LOD2 in one of the posts on our blog (you can check it out here).

Upcoming webinar is just one of the webinars in the series describing tools released as LOD2 Stack – tools that will help you (and us) create, enrich, interlink and visualize open data. First webinar (November 2011) was in an introduction to LOD2 Stack, while second one  (December 2011) presented Virtuoso universal server for linked open data.

If you think this has nothing to do with you, think again. :) We all can contribute in this way or another to create new knowledge, better data and share it with others. There are already a bunch of cool projects related to Open data (ever heard about Freebase? Or DBpedia?) and contributing to “open things” it’s a good idea. :)

Back to announcement…

On January 24, 2012 @ 4p.m. you can participate in third free LOD2 webinar about OntoWiki. OntoWiki is a tool providing support for agile, distributed knowledge engineering scenarios. It enables intuitive authoring of semantic content, it supports RDF, it fosters social collaboration and much more.

Date: 24.01. 2012, 04.00pm – 05.00pm CET
Information & Registration: https://www2.gotomeeting.com/register/772475346

More information about webinar and registration: LOD2 webinar page.

It’ll only take one hour but it might change the way you see data for ever… ok, for now :)

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