Talk Digger, Semantic Web, Web

Using SIOC ontology to connect Talk Digger with other online communities

Talk Digger: “Semantic Web Ready”

As you probably know, I am currently working on a new version of Talk Digger since a couple of months. One of the features I wanted for this new version was to make Talk Digger “Semantic Web Ready”. I wanted to be able to broadcast its content data in such a way that people could create new services above it.


SIOC ontology to describe Talk Digger’s online community

Since, I mostly finished developing the infrastructure, the features and the user interface of the next version of Talk Digger. Then I started to think about this problem. At first I was thinking to develop an ontology to describe what is a “conversation evolving on the Web”. Then started to refresh my memory on the best practices to develop an ontology. One of the first steps was to search for ontologies I could re-use in the one I was expecting to develop. I have done my research using Swoogle. I finally found the SIOC ontology (Semantically-Interlinked Online Communities). I started to read their publications, the specification, and the forums and then I found exactly what I needed.

At a first glance, when you read the class and property names, you can’t do any correlation between that ontology and Talk Digger. However, when you start reading their descriptions and start to map the SIOC terms with the Talk Digger functionalities, you start to see emerging how Talk Digger is becoming an online community.

After I realized that the SIOC ontology is exactly the ontology I wanted to develop for Talk Digger (even if the names are not really relevant with Talk Digger’s). Also, using existing ontologies is always better than creating new ones. For these reasons I choose to use SIOC to share Talk Digger’s content to the world and making it “Semantic Web Ready”

First of all, I would suggest you to check back these screenshots of the new version of Talk Digger before continuing to read this post:

Some screenshots of the next generation of Talk Digger


Mapping SIOC classes and properties to Talk Digger functionalities

The first step if to map the SIOC ontology terms to the Talk Digger’s web site functionalities. Take a look at the schemas bellow to check that mapping. At the left you have the SIOC ontology classes and properties (I only put the properties that create relations between classes. Properties like sioc:topic, sioc:description, etc. are not on that schemas for clarity’s sake). At the left you have the Talk Digger system. In the middle you have the relations between the SIOC ontology and Talk Digger.


Update [15 June 2006]:

This schemas changed since its first publication. I added the sioc:topic property to the sioc:Forum and sioc: Post classes. I use the tags defined by Talk Digger users to find the topics of the Forum and the Posts. The 3 most tagged words are used as conversation topics.

Additional Note:
These changes are not reflected in the RDF and SVG documents(RDF graphs) bellow.

[Click on the schemas for the Full View]


Description of the schemas

  • The sioc:Site instance is Talk Digger’s web site (
  • A sioc:Forum is a Talk Digger conversation page. I consider that a conversation page is a forum. The topic is in relation with the web document that started the conversation. So each time that a new URL is tracked by Talk Digger, then a new “forum” is also created. Forums are interlinked together, so if a url A and B are tracked by the system and that the web document at the url B link to the url A we will have: sioc:Forum(A ) – sioc: parent_of –> sioc:Forum(B ) AND sioc:Forum(B ) — sioc:has_parent –> sioc:Forum(A )
  • A sioc: Post is a comment wrote by a Talk Digger user on a conversation page. So each time a user write a comment, a sioc: Post is created in the sioc:Forum.
  • A sioc:User is a Talk Digger user. A Talk Digger user is defined by his internal and unique username. The personal description of the sioc:User is related (via the rdfs:seeAlso property) to it’s FOAF profile (archived in the Talk Digger System).
  • Each time a conversation page is created in the system, a related sioc:Usergroup is also created. Each time a user start to track that conversation using Talk Digger, it also subscribe to the sioc:Usergroup. So: sioc:User(A) — sioc:member_of –> sioc:Usergroup(conversation)


Special case with sioc:Forum

As I said above, two sioc:Forum can be linked together if a url A and B are tracked by Talk Digger and that the web document at the url B link to the url A.

But what happen if the url A link to the url B too?



There is a circular loop in the model: both sioc:Forum are child and parent.

In the context of Talk Digger, it tells me that A is part of the conversation started by B and B is also part of the conversation started by A. It makes sense in that point of view.

However I am not sure that it semantically makes sense in the context of the SIOC ontology.


sioc:reply_of and sioc:has_reply to recreate the course of events

The sioc:reply_to and sioc:has_reply of the sioc: Post class are really great in the context of Talk Digger (and blog comments) because systems will be able re-create the course of events, without needing dates, only by following the graph created by these relations.



In the next days I will implement the SIOC ontology in Talk Digger and then I will post a snippet of the generated code for peer review.

I am pretty sure that using the SIOC ontology in Talk Digger will give the possibility to other people to use its content in a pretty and novel way.

I could even make Talk Digger a SIOC data warehouse that could crawl SIOC content sites and add them into Talk Digger conversations.


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4 thoughts on “Using SIOC ontology to connect Talk Digger with other online communities

  1. Wow – a really cool application of the SIOC ontology…

    That circular reference thing with Forums may be unique to TalkDigger, but I see what you’re getting at… We haven’t introduced a child_of yet anyway, we just used has_parent for the inverse…

  2. Hi John,

    Heheheh, I am thinking: how the hell my mind worked on that one? What probably happened is that I read the description of has_parent (the two last words are “child of”) a then my mind stick with these two terms and I used child_of instead of has_parent. However I done this mistake only in that schemas and I just fixed it, so everything is fine by now.

    Thanks for reporting it!



  3. hi
    please notice that “sioc:reply_to” is not the correct property!
    the correct property is “sioc:reply_of” with an F not a T.
    i know the wordpress exporter currently does the T mistake, but let’s make sure the mistake doesn’t spread.

    have a ball

  4. another thing:
    adding dcterms:created could be cool – add some time and date to the posts.
    changing dc:title with sioc:

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