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About


PingtheSemanticWeb.com is a web service archiving the location of recently created/updated RDF documents on the Web. If one of those documents is created or updated, its author can notify PTSW that the document has been created or updated by pinging the service with the URL of the document.

PingtheSemanticWeb.com is used by crawlers or other types of software agents to know when and where the latest updated RDF documents can be found. So they request a list of recently updated documents as a starting location to crawl the Semantic Web.

  1. How does it work?
  2. How to link a RDF document from a HTML file?
  3. How to deliver a RDF document using content negotiation?
  4. How to get the list of latest pings from PTSW?


How does it work?


You can use the URL of an HTML or RDF document when pinging PingtheSemanticWeb.com web service. If the service finds that the URL points to an HTML document, it will check if it can find one or more links to RDF documents. If it finds one, it will follow the link and check the RDF document to see if the document is valid. If the service found that the RDF document is valid, it will archive the ping and make it available to crawlers in the export files. If it is not, then PTSW will simply discard the file. Also, for each URL, PTSW will try to do content negotiation with the remote web server to try to find RDF/XML, RDF/N3 or RDF/Turtle by this method. The Accept header parameter sent by PTSW is the following one:

Accept: text/html, html/xml, application/rdf+xml;q=0.9, text/rdf+n3;q=0.9, application/turtle;q=0.9, application/rdf+n3;q=0.9, */*;q=0.8

If the Web server returned a text/html document, then PTSW will send a second query to try to get a RDF document too with the following Accept header parameter:

Accept: application/rdf+xml, text/rdf+n3, application/turtle, application/rdf+n3


How to link a RDF document from a HTML file?


You can tell to PingtheSemanticWeb.com that a RDF document is available from that page by adding this <link> element into the <head> element of your HTML document:
  • RDF: <link rel="meta" type="application/rdf+xml" title="name-of-the-ontology-used" href="[url]" />
where [url] is the URL of RDF document that is linked from the HTML document.


How to deliver a RDF document using content negotiation?


You can tell to PingtheSemanticWeb.com that a RDF document is available from a URL using content negotiation.

The idea is to check the "Accept" HTTP header parameter sent by the requester. If the users wants a RDF document, you application should send back the RDF document of the information available at that URL. In our case, PTSW understand and can receive the following mime types:
  • application/rdf+xml
  • text/rdf+n3
  • application/turtle
  • application/rdf+n3

Any of these document types will be processed equally by PTSW.

Just make sure that when your web server send one of these documents to the requester, to change the "Content-Type:" parameter of the HTTP answer and to put the same mime as the requester requested.

 

How to get the list of latest pings from PTSW?

 

First you have to register an account on PTSW. When registering this new user, you have to put the IP of the server that will request the list. This step will register your server with the PTSW web service.

Once the account is created, and the IP registered, the server can start downloading the xml file describing all the latest pings here available at this URL: http://pingthesemanticweb.com/export/

The data format used to export the list of pings is explained here.

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