Archive for the 'Ping the Semantic Web' Category

A New Home for UMBEL Web Services

umbel_wsEight months ago we announced the dissolution of Zitgist LLC. This event led to the creation of a sandbox to keep alive all the online assets of the company. Since this sandbox server was not owned by Structured Dynamics, it was becoming hard for us to update UMBEL and its online services. It is why we took the time to move the services back on to our new servers.

A New Home

sd_logo_260Structured Dynamics LLC now hosts a new version for the UMBEL Web services. From the main menu at the SD Web site you can access these services under the “umbel ws” menu option (you can also bookmark the Web services site at or

This move of UMBEL’s Web services to a new home will make the future upgrade of UMBEL easier, and this will make the maintenance of the Web services endpoints easier as well. With this move, I am pleased to announce the release of five initial Web services and one visualization tool:

Lookup Web Services:

Inference Engine Web Services:

SPARQL endpoint Web Service:

Visual Tool:

Note that the visual tool is using Moritz Stefaner’s Relation Browser.

Ping the Semantic Web

ptswlogo160.gifAdditionally, the Ping the Semantic Web RDF pinging service is now the property of OpenLink Software Inc. OpenLink is now hosting, maintaining and developing the service.

Ping the Semantic Web version 3: a brand new system!

ptswlogo160.gif Pinging and receiving list of newly created and updated RDF resources has never been easier! I am pleased to announce the release of the latest version of Ping the Semantic Web.

In this brand new system you have access to a:

  1. Validated RDF resources
  2. Simplified pings list export system
  3. Faster pinging infrastructure
  4. Brand new user interface
  5. New statistics

1. Validated RDF resources

In the version 2.0, PTSW was doing a pseudo validation of RDF files. In the version 3.0, it fully validates RDF documents. This means that all pings the service export are valid RDF documents.

This is a major upgrade to the system since now all agents requesting pings from PTSW will know that each of them are valid RDF documents. That way, they will save time and bandwidth since they won’t try to process bad RDF documents.

2. Simplified pings list export system

Now all ping consumers need to be registered to the PTSW web service. This simple registration greatly helps consuming pings coming from PTSW. There are the steps to follow to get pings from the server:

  1. The user have to register an account on
  2. He has to register the IP address of the server that will download the xml file listing all the latest pings received from the system
  3. Additionally, he has to setup his pings retrieval preferences in the user account section.
  4. The registered web server has to request the xml file at:

What improved is the way applications get pings. Now a web server only has to request the xml file, and PTSW will take care to created the xml file according to the user’s preferences.

Finally, PTSW is archiving the time of the latest request of the user. Next time the user’s server will request this document, it will receive the xml file with all the pings received by PTSW since its last request.

This is a major improvement since if the user’s web server was down for 2 days, for some reason, it won’t lose any pings since PTSW will send him all the pings received by the service in the last 2 days.

Note: all current Ping the Semantic Web ping consumers have to create an account and change their application accordingly.

3. Faster pinging infrastructure

The web service is now hosted on a much bigger server. We also switched from MySQL to Virtuoso. These changes result in a more powerful service that I estimate to be able to handle up to 5 million pings per day (in the best of the World with fast remote web server delivering the RDF content). In any case, it is probably enough for the next year’s expansion.

4. Brand new user interface

We also spent some time refreshing the user interface of the web service. This new interface will help us to easily integrate new features and sections to the service’s web site along with keeping it appealing to users.

5. New statistics

New statistics on the state of the service are now available.

  1. All stats about Namespaces. This is the list of namespaces used to describe entities in RDF. For example, if a RDF document has an entity types as a sioc:Post, then the SIOC namespace will be added and its stat counter will be incremented by one. There is currently 347 used namespaces know by PTSW.
  2. All stats about Types. This is the number of typed entities defined in each RDF document know by PTSW. For example, if a RDF document has four foaf:Person defined, then four will be added to the counter. If the same entity (URI) is defined in two different RDF documents, the type of the entity will be calculated twice. So take these numbers as a good approximation, but not as an absolute truth. There is currently 2773 types know by PTSW.

Some people will notice that the current numbers in the sidebar are completely different from the ones that were on the old website of the service. They are right, and there is the reason: I pruned the and pings from PTSW.

In fact, when I started the web service, I added these two RDF data dumps to PTSW. At that time, initiatives such as the Linking Open Data Community didn’t exist and people didn’t know how to export their RDF data dumps. So I choose to include them in the PTSW system. Since then, methods improved and things changed. Now RDF data dumps are available directly from these web sites, data dump repository exists, and people don’t use PTSW for that reason. In fact, they use the PTSW exportation feature to synch their service, and not to get complete datasets from them. This said, I pruned all these 7 000 000 documents from the system leaving about 845 000 “wild” RDF documents in the system.

It is the inclusion of these complete data sources that were increasing the stats compared to today’s stats.


When I created Ping the Semantic Web more than one year ago, I hoped developers would use the service to easily find RDF data without crawling the entire. I hoped that this web service would be a vector of semantic web application development. I think that it succeeded in some ways when I think about services such as SIndice and DOAPStore that emerged from the PTSW initiative.

This new version of Ping the Semantic Web tries to go further in that directing: making thinks even simpler for RDF data consumer and giving them a more powerful RDF discovery service.

Note: make sure to refresh the DNS cache of your desktops and servers so that you see the new, and not the old, PTSW web site. now available in DOAP: 43 000 new DOAP projects

Three weeks ago, Rob Cakebread contacted me vis-à-vis some possible issues with the web service. Rob is involved with the development of Gentoo Linux and he wanted to come-up with a method to let their development teams know when new packages are released for some projects. Since the RSS feeds of are limited in length, and that they do not support DOAP, he started to think about a way to convert’s data projects into RDF using the DOAP ontology. That way, he could easily create services to track the release of new packages and then increasing the effectiveness of their development teams.

Rob wrote:

I came across when trying to determine how many package indexes are using DOAP right now (so far I’ve only found Python Package Index and O’Reilly’s Code Zoo).

I’m a developer for Gentoo Linux. A website I created (Meatoo) checks Freshmeat twice a day and finds packages that have new releases available. We have a database of all our maintainers grouped into ‘herds’, a Python herd, desktop herd, PHP herd etc. The developers in the herds can query my website by a command-line client that uses XML-RPC, or subscribe to RSS feeds by herd or package name, or read the website itself and see which packages have new releases.

DOAP fits into this because I was thinking about creating DOAP records for each release from each package index and making this available so people can write tools to find out information about software packages easily.

Its how we got in contact. Rob had a practical problem, then he tried to find a way to resolve it and to help other people to resolve it too; and its how he found and other semantic web related projects and communities (such as the Linked Open Data). in DOAP

Then a couple of days ago, Rob re-contacted me to let me know that the’s 43 000 projects description is now available in RDF.

He created a prototype service that converts the data he has aggregated from into DOAP. Its project is called DOAPSpace. The idea is to make available the projects into DOAP, then to ping to ultimately make them available on that is feeded by PTSW.

People can get the DOAP description of each project by going to:<project_name>

There are some examples of URIs:

RDF dump

I was really pleased to see how Rob managed to generate that data. Then I asked him if a RDF dump of that precious data would eventually be available for download? It is exactly what he is doing at the moment, and as soon as he send me the dump, I will make it available via Then, it will be ready to be integrated into the Linking Open Data project.

Content Negotiation

At the same time, Rob added a new feature to its service; a user only has to append the “?zg=1″ parameter to the URL to get redirected to the Zitgist Browser. It was really nice from him to think about that; I really appreciated.

However, I introduced him at how he could use content-negotiation to do that and to make its service compatible with other tools such as other RDF browsers. So I pointed him to the How to Publish Linked Data on the Web draft document so that he can have a better understanding of the content-negotiation process.

Linking Open Data Community and Early Developers

Rob is certainly an early adopter of the Semantic Web. He is a developer that wants to solve problems with methods and technologies. He had the intuition that the DOAP ontology and other semantic web principles and technologies could help him to solve one of its problems. This intuition leaded him to discover what the semantic web community could do to help him.

It’s the kind of user we have to take care of; and that we have to help to release their projects. Its people like Rob that will make the Semantic Web a reality. Without such early adopters, from outside of the Semantic Web Community, the semantic web is probably doomed. We are there now; ready to help developers to integrate semantic web technologies into their projects; to generate their data into RDF and to link it with other data sources. It’s the goal of communities like the Linking Open Data Community and its what we are about to do.

This blog is a regularly updated collection of my thoughts, tips, tricks and ideas about my semantic Web researches and related software development.

RSS Twitter LinkedIN


Get every new post on this blog delivered to your Inbox.

Join 69 other followers:

Or subscribe to the RSS feed by clicking on the counter:

RSS Twitter LinkedIN