Semantic Web : Concept vs Document

October 21, 2006

With feedback and help from the blogosphere we have updated the geonames ontology and fixed some flaws in the corresponding web service. The ontology now includes linked data such as contains (administrative divisions), neighbours (for features with a boundary) or nearby features. The web service is using two URIs to clearly distinguish between Concept (the thing as is) and Document (the document about it).

Concept vs Document

In the Semantic Web an URL is not just an URL. Four uses of an URL can be identified : the name of the URL, the concept the URL stands for (the thing as is), the web location and the document instance. It is important to clearly distinguish between the concept and the document instance about it. In the Geonames Semantic Web we use these URIs for Berlin:

[1] http://sws.geonames.org/2950159/
[2] http://sws.geonames.org/2950159/about.rdf

If you want to express the fact that you are living in Berlin you use the first URI [1], if you want to make a remark about the information geonames has about Berlin then you use the latter [2].

The geonames web server is configured to return a 303 (See Other) redirection response for a request of [1] the URI for the concept and give [2] as the new location of the document. This is one way how the Technical Architecture Group (TAG) of the W3C has decided to resolve the ambiguity between concept and document and this is also how Tim Berners-Lee has asked us to resolve it. The other accepted way to remove the ambiguity is the use of hashes in the URI.

Future Work

Wit the new linked data (contains,neighbours,nearby) the toponyms are now interlinked with each other and the geonames semantic web has become a real Web. With over 6 million toponyms there are over 6 million ways to enter the Geonames Semantic Web. However, there is currently not a single way to leave it once you have entered it. It has become a huge “Black Hole“.
A next step will be to add links to other resources in the geospatial semantic web domain. Bernard is involved in the design and development of a Semantic Web implementation for the French National Institute of Statistics (INSEE) and we will link the Geonames Resources with their corresponding resources in the INSEE Semantic Web. It will thus be possible to follow the link from the Geonames toponym to the INSEE.
What other Geospatial Semantic Web Resources should Geonames link to? We are looking forward to your comments.

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11 Responses to “Semantic Web : Concept vs Document”


  1. [...] For additional information about Geonames ontology v1.2, see Marc’s post at the Geonames blog. Sharing is Good.These icons link to social bookmarking sites where readers can share and discover new web pages. [...]

  2. ReLuc Says:

    I would like to submit the idea to have a root element in the contains.rdf file or neighbours.rdf file. this root element could be :

    This give use the possibility to fusion easily the information between:
    http://sws.geonames.org/6295630/
    and
    http://sws.geonames.org/6295630/contains.rdf

  3. ReLuc Says:

    the root could be like this:
    rdf:Bag
    rdf:type=”http://www.geonames.org/ontology#childrenFeatures”
    rdf:about=”http://sws.geonames.org/6295630/contains.rdf”

  4. marc Says:

    Hi ReLuc

    We noticed the flaw ourselfs and had deployed a fix with a backlink to the root item in every Feature moments after you have posted your comments. What do you think about this solution?
    Bernard, our RDF expert, is unexpectedly tied up with his day job. We will discuss other options as soon as he has more time available.

    For neighbours and children it is more a Collection than a Bag, as we have all neighbours and all children not only some of them in the list. With nearby it is different, here have the first x Features within a radius of y.

    Marc

  5. ReLuc Says:

    Hi Marc,

    I think the backlink to the root feature is not the solution because if we made the request on the feature we have the information on the parent feature.

    In Mozilla, we can made a datasource collection which is a datasource with all the resource of the datasources added. For example if I want to have geonames world information, features contained by the world and information about europa, I have to add in a collection datasource http://sws.geonames.org/6295630/ , http://sws.geonames.org/6295630/contains.rdf and http://sws.geonames.org/6255148/ . All the triplets of these 3 datasources are in only one datasource.
    If the resource http://sws.geonames.org/6295630/contains.rdf is not the container of the other resources of the file at this URL there are no link in my collection datasource between the resource world and europa.
    It’s why I proposed to made this type of root resource.

    In RDF a collection is a Bag if they are no order, a Seq if they are an order, Alt if they are an alternative and only one is selected.

    René-Luc

  6. Robert Says:

    Which kink of URL we have to use for FOAF profiles? /geonameid/about.rdf or /geonameid/ ?
    Thank you

  7. marc Says:

    In a FOAF profile you want to express where someone is living. This means you will use the concept URL /geonameid/
    The document URL /geonameid/about.rdf is just a description with some information about the place, but in order to refer to the geographical location the concept URL should be used.

    Hope this helps.

    Marc


  8. [...] has three objects, Map, RDF Data and Wikipedia Article. From what I understand from this article http://geonames.wordpress.com/2006/10/21/semantic-web-concept-vs-document/, the difference between the Concept and it’s associated features vs the Document is that the [...]

  9. jhonathan Says:

    Good afternoon. I wonder where I can get a list of the geonames ontology of properties. I’m looking for a lot, and not found.

    Thank you.


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