Some days ago I was checking how I could use the SIOC (Semantically Interlinked Online Communities) ontology to broadcast/share Talk Digger’s content in a meaningful way. (read more: Using SIOC ontology to connect Talk Digger with other online communities)

 

The implementation using RDF

Now it’s time to implement it by formatting that content using RDF/XML following the ontology’s guideline.

To create a good ontology you have to process by iteration: refining the ontology with testing and peer reviews.

Implementing an existing ontology in a system (such as Talk Digger) also has that process: generating a RDF file accordingly to the ontology and then trying to figure out how to link everything together (defining URI classes, defining resources, linking to resources, etc.) to optimize the graph (optimizing the relations betweens the resources to have as much meaning (easy to query) as possible).

 

Visualizing the RDF graph using IsaViz

The tool I used to implement the SIOC and the FOAF ontologies in Talk Digger is a RDF editor/visualization tool called IsaViz.

My procedure was simple:

1. Generating the RDF/XML files (accordingly to SIOC and FOAF) with Talk Digger’s content database.
2. Importing the RDF/XML file in IsaViz.
3. Visualizing and analyzing the resulting graph.
4. I checked all the relations between the resources and tried to figure out if it was possible to cut/add some of them to simplify/optimize the resulting graph.
5. I checked all the anonymous nodes (bNodes) of the graph and checked if it was possible to relate them to an existing resource.
6. I performed these 5 steps until I was satisfied by the resulting graph.

 

Playing with URIs and xml:base

What is great is that I can distribute Talk Digger’s content anywhere on the Web (with different URLs) and a crawler can download all these snipped of content (FOAF profiles, conversations content, etc.), aggregate them and merge them in a unique RDF graph. That way they can have their hands on all the relations that exist in the Talk Digger system and then querying it(the RDF graph) in useful and meaningful ways.

All that magic is possible by the fact that we can define a different URI for a given RDF/XML document using the xml:base attribute. That way I can:

 

• Host a RDF/XML document at the URL http://talkdigger.com.com/a.php
• Define the xml:base with the URI “http://talkdigger.com.com/db/”

• Host a RDF/XML document at the URL http://talkdigger.com.com/b.php
• Also Defining the xml:base with the URI “http://talkdigger.com.com/db/”

 

Then if a crawler downloads both RDF documents “a.php” and “b.php”, it can merge them to recreate the single RDF document defined at “http://talkdigger.com.com/db/”. By example, this merged RDF document would be the graph of all relations defined between Talk Digger’s content.

 

Talk Digger’s URI classes

I refer to a “URI class” when I talk about a “part” of a URI that is general to many URI “instances”. I refer to an “URI instance” when I talk about a URI that refer to a resource.

By example, the “URI class” of Talk Digger subscribed users is:

http://www.talkdigger.com/…/user.php?nick=

But an “instance” of that “URI class” would be the URI that describe a particular Talk Digger user:

http://www.talkdigger.com/…/user.php?nick=fgiasson

In that example, this “instance” refers to a resource that is the Talk Digger subscribed user called “fgiasson”.

There are the “URI classes” defined in Talk Digger:

• URI class referring to a conversation container (work as a container for the conversation components)

http://www.talkdigger.com/…/conversation.php?url=[$url]

• URI class referring to a conversation

http://www.talkdigger.com/…/conversation.php?url=[$url]#conversation

• URI class referring to a usergroup (a group of users tracking that conversation)

http://www.talkdigger.com/…/conversation.php?url=[$url]#usergroup

• URI class referring to a subscribed user

http://www.talkdigger.com/…/foaf.php?nick=[$nick]

 

SIOC and FOAF instances generated with Talk Digger content

In the next sections I will show you how Talk Digger will use the SIOC and FOAF ontologies to broadcast/share its content.

I’ll use 3 RDF documents for my presentation:

1. sioc-fgiasson.rdf. This file describe the conversation evolving around my personal website [fgiasson.com] (in fact it is only a snippet for the example’s sake).
2. foaf-fgiasson.rdf. This file is the FOAF profile of my Talk Digger user [fgiasson].
3. sioc-blogspot.rdf. This file describe the conversation evolving around a specific blog post on a Blogspot blog called “Guilty of being…”. This blog post refers to an article I wrote on my blog.

All the RDF graphs have been exported in SVG files from IsaViz. Many mainstream applications like Visio or CorelDraw can read these files. If you don’t have access to one of these software you can refer to that list of tools to read SVG files (I am unfortunately not able to find any tool to convert a SVG file into a huge JPEG or GIF file).

Note: the path of the interesting results I found in these graphs are highlighted in red.

 

The SIOC document describing the conversation evolving around fgiasson.com

You can download the RDF document here: sioc-fgiasson.rdf.

The resulting RDF graph of this document is available here: fgiasson-conversation.svg

What is interesting in that graph is the interaction between

-a sioc:User
-[http://www.talkdigger.com/…/user.php?nick=fgiasson]

-a sioc:Usergroup
-[http://www.talkdigger.com/…/conversation.php?url=fgiasson.com#usergroup]

-some sioc: Post
-[http://www.talkdigger.com/…/conversation.php?url=fgiasson.com#comment-1]

-a sioc:Site
-[http://talkdigger.com]

-a sioc:Forum
-[http://www.talkdigger.com/…/conversation.php?url=fgiasson.com#conversation]

 

Merging a FOAF document with this SIOC document

Now I merged the FOAF document that describe more in deep my sioc:User fgiasson.

You can download these RDF documents here: sioc-fgiasson.rdf, foaf-fgiasson.rdf

The resulting RDF graph of these documents is available here: fgiasson-conversation-foaf.svg

The link between the FOAF to the SIOC document is made using the foaf:holdsAccount property. The result is:

[http://www.talkdigger.com/…/foaf/foaf.php?nick=fgiasson]
— foaf:holdsAccount —>
[http://www.talkdigger.com/…/user.php?nick=fgiasson]

The link between the SIOC to the FOAF document is made using the rdfs:seeAlso property. The result is:

[http://www.talkdigger.com/…/user.php?nick=fgiasson]
— rdfs:seeAlso —>
[http://www.talkdigger.com/…/foaf/foaf.php?nick=fgiasson]

If you take a closer look at the resulting RDF graph, you will see that I highlighted a “loop” in red. This is one of the really interesting results when you merge different ontologies.

What is happening here? By merging the FOAF document of the “fgiasson” user with the SIOC document of the “fgiasson.com” conversation, I uncovered some interesting relations.

In fact, the sioc:User “fgiasson” is a friend of “dgiasson” another sioc:User. However, it was impossible to know that fact before merging the two documents because that information is held in the FOAF document and not the SIOC one! At the same time, we know that “fgiasson” and “dgiasson” also belong to the same sioc:Usergroup
[www.talkdigger.com/…/conversation.php?url=fgiasson.com#usergroup].

That way we are able to extend the power of our queries because we are able to know who are the people that belongs to a sioc:Usergroup and that are also friends. We could possibly even extend that feature by using the “relationship” ontology and then developing some type of trust networks by analyzing the relationships between people belonging to a same group.

 

Merging a new SIOC document to that RDF graph

Finally I merged another SIOC document that describes a conversation evolving around a blog post that link-back to the conversation about “fgiasson.com”.

You can download these RDF documents here: sioc-fgiasson.rdf, foaf-fgiasson.rdf, sioc-blogspot.rdf

The resulting RDF graph of these documents is available here: fgiasson-conversation-foaf-other-conversation.svg

In this graph I highlighted in red the fact that a sioc:User “fgiasson” is a member of two different sioc:Usergroup and that a sioc:Forum is the parent of another sioc:Forum.

 

Conclusion

In this blog post I described how I would use the SIOC and the FOAF ontologies to share the content available on Talk Digger.

There are probably some glitches, errors, or best-practices (I don’t follow) in the way I handle some classes and/or properties of these ontologies (specially about how to relate a sioc:User and a foaf: Person). Considering this it would be really appreciated to report any glitch/errors/best-practices you find to help me improving this implementation in Talk Digger.

Technorati: sioc | foaf | semantic | web | rdf | talkdigger | xml | svg | ontology | online | communities | conversation |

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.

 

[Click on the schemas for the Full View]

 

Description of the schemas

• The sioc:Site instance is Talk Digger’s web site (talkdigger.com)
• 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.

 

Conclusion

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.

 

Technorati: sioc | online | communities | semantic | web | talkdigger | rdf | xml | owl |