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Jonas Yuan
Proposal: Liferay 6 and Semantic Web
May 10, 2010 11:03 AM
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Jonas Yuan

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Thanks to Jorge, who commented the blog Liferay 6 and Semantic Web. It would be better to use the message boards, instead of blog posts, as a way to share ideas, since that will allow everybody to share their ideas so that we could come up with the best design possible. Thus I posted the same using the message boards.

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Liferay 6 and Semantic Web

The Semantic Web is an evolving development of the World Wide Web in which the meaning (that is, semantics) of information and services on the web is defined, making it possible for the web to understand and satisfy the requests of people and machines to use the web content.

Liferay goes Semantic Web! See ticket: Support RDF - Semantic Web.

The portal tagging system allows us to tag web content, documents, message board threads, and more and dynamically publish assets by tags. Tags provide a way of organizing and aggregating content. Basically, the tag administration determines which tags are available for use. The users use these tags on their content. Any content that is tagged can be grouped or aggregated.

The following figure depicts an overview of tags, categories, and assets:



Abstracted from the book: Liferay Portal 6 Enterprise Intranets

Folksonomies

Folksonomies are a user-driven approach to organizing content through tags, cooperative classification, and communication through shared metadata. The portal implements folksonomies through tags. A tag may be associated with many assets, whereas an asset may have many tags associated with it. This is what we called tagging content. Also, a tag may have many properties. Each property is made up of name-value pair.

A tag may be associated with content. Using tags, you can tag almost anything: Bookmarks' entries, Blogs' entries, Wiki articles, Document Library documents, Image Gallery images, Journal articles and Message Board threads, and so on. You can also use these tags to pull content within the Asset Publisher portlet.

Taxonomies

Taxonomies are a hierarchical structure used in scientific classification schemes. Although taxonomies are common, it can be difficult to implement them. The portal implements taxonomies as "vocabularies and category tree" in order to tag contents and classify them.

You can have more than one vocabulary, which forms a top-level item of the hierarchy. Each vocabulary may have many categories. That is, a category cannot be a top-level item of the hierarchy. However, a category can have other categories as its child or siblings. Therefore, vocabulary and categories form a hierarchical tree structure.

In the same way, a category may have many properties. Each property is made up of a name and a value.

In addition, a predefined category will be applied to any asset. In a word, assets could be managed and grouped by categories.

Category Tree

It is very useful that parent categories can have multiple child categories. This parent-child relationship forms a hierarchical structure. However, categories don't have siblings, for example, left-side category and right-side category. Parent-child relationship plus left-side category and right-side category form a tree called Category Tree. This feature will come out soon.

Why it doesn't merge both kinds of tags using ontology

As you can see, there are two kinds of tags: taxonomies and folksonomies. Both of them can be used as a way of organizing and aggregating content. Folksonomy is a way of classification, creating, and managing tags to annotate and categorize content, whereas taxonomy is a hierarchical structure only for classification.

In fact, taxonomies and folksonomies are different. Taxonomies are a closed set of categories (also called tags) and the vocabulary, created and organized in a hierarchical structure. It helps standardization, especially when you store it in the Shared Global group to standardize categorization through all of the organizations. In a word, folksonomies are an open set of tags, which are extended by the end user.

Why can't we merge both of them through ontology? Ontology—the study of entities and their relations—is less concerned with what "is" than with what is possible. The answer would be "yes".

What's next?

  • Ontology support

Merge tags and categories through ontology.

  • RDF - Sematic Web (Web 3.0) - support

RDF is a standard model for data interchange on the Web. RDF has features that facilitate data merging even if the underlying schemas differ, and it specifically supports the evolution of schemas over time without requiring all the data consumers to be changed.

RDF extends the linking structure of the Web to use URIs to name the relationship between things as well as the two ends of the link (this is usually referred to as a "triple"). Using this simple model, it allows structured and semi-structured data to be mixed, exposed, and shared across different applications.

This linking structure forms a directed, labeled graph, where the edges represent the named link between two resources, represented by the graph nodes. This graph view is the easiest possible mental model for RDF and is often used in easy-to-understand visual explanations.

See details of RDF at http://www.w3.org/RDF

Your suggestions or comments or vision?

Jonas Yuan
---------------------------
The Author of Liferay Books:
Liferay Portal 6 Enterprise Intranets
Liferay Portal 5.2 Systems Development
Liferay Portal Enterprise Intranets
Jorge Ferrer
RE: Proposal: Liferay 6 and Semantic Web
May 12, 2010 5:08 AM
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Jorge Ferrer

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Hi Jonas,

The Semantic Web is certainly a set of technologies that make a lot of sense for Liferay Portal. As you know Liferay already supports some microformats and I think it would be a good idea to extend this support, most probably through RDFa (or maybe microdata?).

Our current support for categories is certainly part of that, but the whole concept of the Semantic Web and Linked Data is much more than that.

BTW, Bryan posted in his blog recently about a Linked Data module for Liferay that seems very promising: http://www.liferay.com/web/bryan.cheung/blog/-/blogs/4354309
Jonas Yuan
RE: Proposal: Liferay 6 and Semantic Web
May 12, 2010 11:25 AM
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Jonas Yuan

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Thank you, Jorge,

Linked Data module would be good to bring Liferay into Web 3.0 - Semantic Web ....

Tobias Hofmann just mentioned Ontopia to integrate Liferay with a topic map.
http://ontopia.wordpress.com/2010/01/12/ontopialiferay-integration/

at http://www.liferay.com/web/jonas.yuan/blog/-/blogs/liferay-6-and-semantic-web

Your suggestions?
Dave Weitzel
RE: Proposal: Liferay 6 and Semantic Web
July 9, 2010 8:23 AM
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Dave Weitzel

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I love the direction Liferay is going with Semantic web and RDF, however there are two areas that I would like to know if you are covering in your plans any time soon.

a) DUBLIN CORE META tags - I have seen posts about this but cant see how it is implemented if at all. (that is web 1.0 I know!)

b) Tags are not synchronized across languages - items tagged "news" in English should be found when searching the equivalent tag in other languages. This probably relies on the Tag creator making links but would really help multi language sites.

Dave
Jeff Zhuk
RE: Proposal: Liferay 6 and Semantic Web
July 11, 2010 5:57 PM
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Jeff Zhuk

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Jonas,

First of all thank you for starting this thread. Usually such discussions bring brilliant ideas from developers inside and outside of the Liferay team. Here are several thoughts to share:

It's great that Liferay is turning into one of the first semantic portals [1]. But what are the main goals for a semantic portal?

1. The most obvious goal might be enabling semantic search or adding content-understanding skills to a portal.
2. Another goal can be to globally connect distributed knowledge resources [2].

Resource Description Framework (RDF) is a perfect instrument to connect distributed data of multiple domains into a global data cloud [3] but there are better mechanisms to express knowledge. For example, Topic Maps, although very similar to RDF, goes further in representing content topics and their relationships [4] . And even more powerful in expressing knowledge is Ontology Web Language (originally DARPA+OIL, later adapted by W3C as OWL standard) or Cyc Language [5].

3. Even more ambitious goal is to automatically act upon knowledge or in other words transform knowledge into application services [6].
OWL was specifically designed as a common way to process ontology by computer systems.
There are multiple tools around this standard. In the open source space, I'd recommend to look at the family of Protege tools by Stanford University [7].

But to successfully move towards these goals, we need a comprehensive ontology model. This model must describe generic common concepts, so it is possible for multiple business domains to add their specifics and still be able to connect to knowledge outside of this specific domain. While multiple specific ontologies are created today by thousands of companies, only Cycorp, Inc. [8] offers a comprehensive generic common sense ontology with hundreds of thousands concepts and millions relationships. Cycorp encoded this knowledge into bits and bytes during the last 30 years and I'd prefer to reuse this work rather than repeat it (available free in OWL and CycL formats as well as their OpenCyc product).

4. Provide ontology portlet that would help to build and sync ontologies.
Yes, there are many of tools specifically designed for this purpose, but take a close look on these tools and you'll see that they are designed by technical people for technical people. The portal and portlet (like wiki) is more natural environment for such task. A subject matter expert (SME), not necessary an IT person, is the one to capture her/his knowledge as business rules and scenarios [9]. Ontology portlet would hide its complexity while helping the SME and making sure that any additions and changes are in sync with the common model. Taking into account that about 70% of the working population will be eligible for retirement in the next 7 years, capturing people's expertise is becoming one of the most important tasks.

Related Links:
1.Semantic Portals Requirements - http://www.w3.org/2001/sw/Europe/reports/requirements_demo_2/
2.Distributed Active Knowledge and Process - http://www.freepatentsonline.com/7032006.html
3.Linked Data - http://linkeddata.org
4.RDF and Topic Maps comparison – http://www.ontopia.net/topicmaps/materials/tmrdf.html
5.Knowledge technologies – http://javaschool.com/EA/5/KnowledgeTechnologies.pdf
6.Knowledge-driven architecture - http://www.freepatentsonline.com/y2005/0149558.html
7.Protege family of OWL tools - http://protegewiki.stanford.edu/wiki/Main_Page
8.Cycorp, Inc., a leader in common sense reasoning – http://cyc.com
9.Capture knowledge with Rules Collector - http://www.freepatentsonline.com/y2009/0144219.html
Jorge Ferrer
RE: Proposal: Liferay 6 and Semantic Web
July 19, 2010 3:55 AM
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Jorge Ferrer

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Hi Dave,

Dave Weitzel:

a) DUBLIN CORE META tags - I have seen posts about this but cant see how it is implemented if at all. (that is web 1.0 I know!)


That's interesting. Do you have a more detailed proposal for how to add support for Dublin Core in Liferay?
For example:
  • For which portlets (or asset types) would you apply it
  • How would the dublin core information be used? Do we need to allow exporting it as XML or RDF?
  • What would be the use cases for the functionality?


Dave Weitzel:

b) Tags are not synchronized across languages - items tagged "news" in English should be found when searching the equivalent tag in other languages. This probably relies on the Tag creator making links but would really help multi language sites.


I tend to think that most times that people need this type of functionality the should really be using categories (that is categorization hierarchies defined by experts). For categories it makes a lot of sense to be able to enter the name in several languages (we have it partly done but will be fully finished for 6.1).

Having said that, for advanced usage of tags it certainly also makes sense to associated them. I think that such relationships should be a bit more generic supporting several types of links. For example I would include the ability to specify that a tag is a synonym of another tag. But I'm not an expert in this topic, so I'd appreciate feedback about it and links to websites or other open source products that have similar features.
Jorge Ferrer
RE: Proposal: Liferay 6 and Semantic Web
July 19, 2010 4:45 AM
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Jorge Ferrer

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Hi Jeff,

Thanks for your feedback. Your post gave me a great excuse to refresh my knowledge of the semantic web, it's certainly been a while since I read about OWL and the associated tooling.

Since we are in the process of defining the roadmap for 6.1, this is the perfect time to try to define out of all the semantic web technologies which would be most useful for Liferay's users. The easiest way to do that is IMHO to try to define specific use cases so that they can be prioritized.

From this use cases we should be able to identify which ontologies we want to support (FOAF, DC, SIOC, SKOS, ...) or even if it would be useful to define some new terms specific to Liferay (for example for the asset framework).

Related to this we need to decide which of the competing technologies we want to invest on. A few versions ago we added support for hCal and had plans to add support for other microformats. Unfortunately microformats seem to be on decline right now. The focus seems to have shifted back to RDFa, but HTML 5 introduces a new alternative: microdata. Which one is best for the goals of a portal platform such as Liferay? Do we have to choose or can we use both?

All feedback about this topic is greatly appreciated. Also, I'd welcome descriptions of use cases or benefits of adding specific semantic features either to the core or to the out of the box portlets.
Jeff Zhuk
RE: Proposal: Liferay 6 and Semantic Web
July 19, 2010 8:39 PM
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Jeff Zhuk

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Jorge,

>try to define specific use cases so that they can be prioritized.

You are right, the best approach is to “define specific use cases”.

I would think the most common use cases are:
- improving content search in Liferay by adding Semantic Search ability
- providing Liferay cloud with Distributed Semantic Search across multiple Liferay installations around the world

Both cases are about the content, not just data.
The standard to express the content is RDF/OWL. OWL is the richer form, based on RDF.
If Liferay can understand OWL it will understand RDF too, but opposite is not necessary true.

While RDF is an early bird and might be more popular and more present today, OWL with its supporting tools and ontologies is growing fast and will probably dominant in the content world.

>which ontologies we want to support (FOAF, DC, SIOC, SKOS, …)

Most of these ontologies are based on RDF/OWL. If RDF/OWL (especially OWL) is selected as a technology for Liferay, you can help Liferay users to easily connect to these ontologies.

So, another use case is:
- providing semantic connections to existing ontologies and creating knowledge cloud.

We would also need initial ontology, so we don't force everyone create their own from scratch.
Such foundation ontology with generic common sence model and vocabulary in hundreds thousands words and relationships is free downloadable from http://OpenCyc.org.

In all these cases we'll need some kind of Triple Store (to store the model and the content in 3 words: Object-verb-Object or noun-predicate-subject). I'd recommend the http://4Store.org open source solution.

This might be a new business line for Liferay – offer a hosting solution for a common Liferay semantic model storage and distributed semantic search (similar but different from openrdf.org).

There are many pieces of this puzzle that could be inherited from the open source community, like RDF/OWL tools from Stanford University: http://protegewiki.stanford.edu/wiki/Main_Page

I'd think about the use case of transforming content, like business process descriptions or application scenarios, directly into application services or into a working application. Not sure if it is a strong case for Liferay.

Thank you for the opportunity to participate in your brainstorming,

Jeff
Jorge Ferrer
RE: Proposal: Liferay 6 and Semantic Web
September 1, 2010 4:27 AM
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Jorge Ferrer

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Hi Jeff,

Sorry that I didn't answer you before. I just wanted to thank you for your suggestions, we'll keep all of them in mind as we start working on semantic web technologies for the next versions and we'll keep you on the loop as we progress.
Tobias Hofmann
RE: Proposal: Liferay 6 and Semantic Web
February 22, 2011 5:30 AM
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Tobias Hofmann

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Hi,

any news on semantics in Liferay? I'm looking at LR 6.1 and trying to emulate a semantic relationship by using categories and tags, while the category is the topic and the tag defines the relationship between them. But of course that is not a real semantic solution.

br,
Tobias
Jorge Ferrer
RE: Proposal: Liferay 6 and Semantic Web
March 4, 2011 9:11 AM
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Jorge Ferrer

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Hi Tobias,

There hasn't been much progress on this area yet due to the lack of time and contributors. Would you like to help?
Chris Buckley
RE: Proposal: Liferay 6 and Semantic Web
May 22, 2011 10:02 AM
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Chris Buckley

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Hi Jorge,

I'm interested as well in the developments of the semantic and how it's going to fit into Liferay. I've been looking at the UIM project at Apache http://uima.apache.org/index.html and starting to think about how this could be put into Liferay. The project has strong support for RDF already and leverages other 3rd party open source systems. My company and myself would VERY much like to contribute on this effort.

thanks,

Chris
Jorge Ferrer
RE: Proposal: Liferay 6 and Semantic Web
May 30, 2011 2:40 AM
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Jorge Ferrer

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Hi Chris,

That's great, it will be great to count with all ideas and contributions that you guys can provide. Feel free to use this thread to follow the conversation and we can later split it into different topics as needed.
Asier Del Pozo
RE: Proposal: Liferay 6 and Semantic Web
June 19, 2011 5:05 AM
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Asier Del Pozo

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Hi,

We are very interested in work on Liferay and Semantic Web, and in order to join to the discussion about this topic, I would like to know your opinion about aplying RDFa or Microdata to Liferay.

Which one do you prefer (RDFa or Microdata)? Do you think that they can coexist in Liferay or we have to choose one of them?

And, do you think the fact that Google, Yahoo and Microsoft are sponsoring a site (http://schema.org), where they propose a Microdata schema for using it into a web page, could make it a standard? Similar to sitemap.org... tipping the balance in favor of Microdata...

Cheers,
Asier
Natasa Bulatovic
RE: Proposal: Liferay 6 and Semantic Web
June 28, 2011 9:01 AM
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Natasa Bulatovic

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Jorge Ferrer:
Hi Dave,

Dave Weitzel:

a) DUBLIN CORE META tags - I have seen posts about this but cant see how it is implemented if at all. (that is web 1.0 I know!)


That's interesting. Do you have a more detailed proposal for how to add support for Dublin Core in Liferay?
For example:
  • For which portlets (or asset types) would you apply it
  • How would the dublin core information be used? Do we need to allow exporting it as XML or RDF?
  • What would be the use cases for the functionality?


"Dublin Core META tags" is a bit strange term. These are known in the library community as metadata - as they are describing a resource - these are not tags. Metadata examples are title, author, date, etc..(see http://dublincore.org/documents/dcmi-terms/)
How they could be associated with a different types of resource, as an example one may check here http://dublincore.org/documents/usageguide/ and here http://dublincore.org/documents/profile-guidelines/
In general, as each term has a URI it can be easily expressed in both RDF/XML and XML (no RDF).

Metadata terms/profiles - may come from different namespaces, not only from Dublin Core .

- It could be applied for every portlet to define the portlet properties itself (e.g. portlet title, subject, creator, date, version of Liferay etc.)
-It could be applied to each resource used/produced in Liferay (web content, web page, document, image, bookmark, message etc..)
-Numerous use cases dealing with interoperability : export/import of resources in/from Liferay to other systems, showing metadata of a bookmarked resource coming from external system, could be made absolutely easier - by using standardized metadata terms to describe the resources - i.e. interoperability, knowledge discovery and sharing.. some links already were provided in this thread emoticon
-especially interesting could be the possiblity to re-use external concept vocabularies and ontologies (see as example: http://www.w3.org/2004/02/skos/ ) that could be applied to resources
-etc..
Natasa Bulatovic
RE: Proposal: Liferay 6 and Semantic Web
December 1, 2011 7:47 AM
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Natasa Bulatovic

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Have anybody checked this project so far? Any experiences?

Liferay Linked Data Module coming from IMC Technologies ( http://www.imc.com.gr )

Download from: http://sourceforge.net/projects/liferayldm/
Ravish Bhagdev
RE: Proposal: Liferay 6 and Semantic Web
July 3, 2012 12:24 PM
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Ravish Bhagdev

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I landed on the same IMC project from years ago when I tried to find what was out there. It doesn't look like much has happened since this discussion was started?

I have good grounding in semantic web technologies but lack Liferay skills to be able to make contributions. I might come back here once I have better understanding of Liferay's code base.