More and more web services start to export some of their data archived in their databases using RDF. Some of them have a specific goal in mind, others only do it “in case of” that someone would need it (like livejournal.com does). In any case, these RDF documents are waiting here, somewhere on the Web, waiting to be read and used.

Ping the Semantic Web’s goal is to act as a central point in that environment: aggregating these RDF documents and then sending them to other services (softwares) that need them.

More and more people are starting to ping the service. It now gets about 5000 ping requests each day and its constantly growing.

In the last couple of days, I contacted some people that are developing systems that export RDF data. I asked them two things:

 

1. Would it be possible for you to make your system pinging Ping the Semantic Web each time it creates or updates a RDF document?
2. Would it is possible for you to send me a list of URLs where Ping the Semantic Web could find the existing RDF documents generated by your service?

 

Today I am asking your help:

If you know a web service that export RDF documents, would it be possible for you to contact me with the name of this service?

Then what I’ll do is contacting them to ask them the two questions. What I’ll also do is helping them (technically) to implement the feature into their system if they encounter any problem.

Currently the service know about 57 000 RDF documents. I predict you that in one year it will knows millions of RDF documents. And what I hope is that many of them will not be serialized using XML but using N3 instead (but I should certainly wait after a wider adoption of SPARQL before seeing that happening).

 

People I already contacted:

• D2R Server publishing the DBLP Bibliography Database (Richard sent me 1.2 million of URL to crawl and he should start to ping PTSW in January (yeah, this is partly why I said that I would had millions of RDF document 😉 )
• Revyu (Tom should start to ping PTSW soon)
• FOAFMap
• FOAFNaut
• Geonames (Just when I was about to publish this article, Marc contacted me telling me that Geonames now pings PTSW each time a geoname changes or is created. Also, he send me a list of 6.2 million of geonames to include).
• Tribe
• Semantic Media Wiki

 

Conclusion

Finally what I am requesting is help from people to try to find as many web services that export data using RDF as possible. That way everybody will benefit from it: they will increase the visibility of the data they are generating and PTSW will see its database of RDF document growing and growing for the benefit of the community.

Technorati: Pingthesemanticweb | semantic | web | web3.0 | rdf | xml | n3 | foaf | sioc | doap | rdfs | owl |

Soon enough I’ll add a SPARQL endpoint to the Ping the Semantic Web service. What it means?

It means that anybody will be able to send SPARQL queries (SPARQL look-like the SQL query language but is used to query RDF graphs) to retrieve information from the RDF documents know by the web service. As soon as someone ping pingthesemanticweb.com with a RDF document’s URL, other people will be able to search it using the SPARQL endpoint.

 

How it will work?

Users will have access web interface where they will be able to write and send SPARQL queries to the triple store (this is the name given to the type of database systems that archive RDF graphs)

For example, they will be able to send queries like:

 

SPARQL
PREFIX sioc: <http://rdfs.org/sioc/ns#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT *
WHERE
{
GRAPH ?graph
{
?s rdf:type sioc: Post
}
}

 

That query to the triple store will return all the resources (things) that have been described (type) as a sioc: Post (a blog post, a forum post, etc.)

 

How to visualize the triples store?

Creating this SPARQL endpoint will be somewhat easy to do. In fact, the structure will remain the same but we will add one new server: a SPARQL endpoint that gives access to a RDF triple store.

There is how one could imagine how triple store works:

 

Figure 1

 

 

 

Figure 2

 

If we take a look at the schemas, each RDF document is a graph in itself. A RDF graph is composed of the relations between resources <subject , verb, object>. For example a relation could be <peter , hair-color, brown> (so Peter’s air color is brown (so the resource “Peter” has the property “hair-color” brown)).

With the triple store, we have the possibility to merge two RDF graphs together. That way, we create a sort of meta-graph with all the relations between one graph and the other.

This is where things are getting interesting.

Ping the Semantic Web’s graph will be created by merging the graph of each RDF documents it knows (via pinging).

That way, users will have the possibility to search this sort of Meta-Graph of relationship between resources by querying it using SPARQL queries.

 

We could possibly talk about the semantic web in a nutshell.

 

Virtuoso to create the RDF triple store

I’ll use a database management system called Virtuoso to create this RDF triples store.

 

A first prototype version

Consider the first version of the triple store as a prototype. In fact, the RDF triple store feature of Virtuoso is relatively new. It is always in development and some things have to be created (to enhance the functionality) and upgraded. However, it is perfect for a couple of hundred of millions of triples (relations), but when we will reach the billion of triples, it is possible that some queries to the system will become unworkable. At that time, I’ll possibly be obligated to restrict users’ requests possibilities to ensure that the system will always be working at its full potential.

In any case, the triple store and the SPARQL endpoint will “live” on another server, so the performance of the current pinging system will not be affected by the performance of the endpoint, they are two totally different entities in our system.

 

Why a triple store with a SPARQL endpoint?

At first: for research and education purposes. People will have the possibility to query a system that aggregate RDF documents “from the wild”. Eventually, such initiative could lead to more interesting technologies development (user interface, anything) that could be used by a broader range of people.

Having this system in hands, one could search the triple store to extract statistics on the RDF documents it knows for research purposes.

Also, it is a way for OpenLink to debug, upgrade and enhance its service that will ultimately benefit to everyone (since an open source version of Virtuoso is available).

 

Conclusion

Keep me in touch if you have any thoughts about that new development with the Ping the Semantic Web service.

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