RDFa Versus Microformats
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RDFa versus Microformats: Exploring the Potential for Semantic Interoperability of Mash-up Personal Learning Environments
Vladimir Tomberg, Mart Laanpere Tallinn University, Narva mnt. 25, 10120 Tallinn, [email protected], [email protected]
A Course as dynamic process
Mash-up PLE have become a fast developing trend
Course is not just a syllabus, it also involves various dynamic processes
These processes can be described by way of metadata using
Which Metadata we need? Course has:
Learning goals
Schedule of learning activities (assignments, discussions)
Registered participants (teachers, students)
Different types of resources
We usually can extract such information from LMS, but how it is possible in case of PLE?
Formats for PLE metadata
(X)HTML is a main format for PLE
(X)HTML syntaxes are not designed for carrying the semantic data
Different technologies were introduced in the past
Microformats and RDFa are two most widespread
Scenario
Teacher publishes a Course’s information by using a web application — blog, wiki, forum or personal web site
Information by means of mash-ups is delivered to learners
Scenario: Data
The Course can contain:
(meta)data about the course syllabus,
pre-requisite and target competencies,
amount of credits,
dates for start and end of the course,
the criteria and form of a final assessment,
contact information of teachers and other participants
Scenario: Features
Teacher can constantly update the course information during time
Teacher assigns lectures, announces an assessment and evaluates learners
Learners thus constantly have the fresh information on everything that happens on a course
Microformats
HTML code:
<a href = "http://creativecommons.org/licenses/by/2.0/" rel="license">cc by 2.0</a>
In browser:
cc by 2.0
Microformats
Standard (X)HTML attributes 'class', 'rel' and 'rev' are used for metadata storing purpose
Not standardized, but well specified and widely known
Endless development
Have no ontologies, formal descriptions or schemes
RDFa
HTML code:
<a rel="cc:license" href="http://creativecommons.org/ licenses/by-nc-nd/3.0/"> Creative Commons License </a>
In browser:
Creative Commons License
RDFa
Standardized by W3C
Uses 10 reserved tags, 5 of them from XHTML2
Can be applied for RDFa only to XHTML2, not for HTML, XHTML1
Mixing different namespaces in one document is possible, for example 'dc:' and 'cc:' simultaneously
Hard to suppose prospect because of end of XHTML 2 support from W3C
Technological Comparison
Microformats
RDFa
Can be applied to HTML, XHTML In current state for XHTML 2 and limited for XHTML 1
Have useful implementations for end user today
Yes, different add-ons for browsers allow that
Not very useful for end user directly today
Can be used in mash-ups Yes Yes
Practice using for semantic indexing examples
Google and Yahoo now indexing such microformats as hCard and hReview
Google, US Government Website and Slideshare use RDFa
Standardized No W3C Recommendation
Drawbacks One limited dictionary for all purposes.Because of absence of standards support from developers is more enthusiastic than industrial
Because of finishing of XHTML2 development the perspectives of RDFa are very unclear at the current moment
Semantic Comparison
Microformats
RDFa
Vocabulary Only one Unlimited amount is possible
Vocabulary can be extended
Yes, but only through community
Yes, freely
Interoperability level High Interoperability is possible only if known vocabularies are used
Possibilities to add semantic value to data
Average High
Application for educational needsMicroformats RDFa
Course’s membership via hCardLearner and Teacher information via hCardMembers relations via XFNCourse events via hCalendar
Can use any semantic vocabulary that suitable for course description
Implementation on Wordpress
Vladimir Tomberg, Mart Laanpere
Towards Lightweight LMS 2.0: A Blog-based Approach to Online Assessment,
EC-TEL 2008 Maastricht, The Netherlands
Under development at present
Conclusion
Which technology is more suitable?
Microformats
Good simplicity of adaptation to web;
Limited vocabulary for educational needs;
RDFa
More flexible and semantically rich;
Unclear prospect because XHTML2 developing is stopped