Academic journal article Library Philosophy and Practice

Embedding Semantic Markup in Web Pages

Academic journal article Library Philosophy and Practice

Embedding Semantic Markup in Web Pages

Article excerpt

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Introduction

The World Wide Web first revolutionized the presentation of text and data. People thousands of miles away from each other could suddenly see the same exact text or data at the same time in the same format. The second wave of data handling has come with the collaboration technologies: social tagging, networking websites like Facebook and the interactivity of Wikis and blogs. Both of these technology sea changes have been aimed at making data accessible to people. Both have improved a person's ability to read the text or data presented and interpret meaning from it, for good or for ill. The next wave of technology will make data accessible to computers as well as people. Instead of undifferentiated text presented on a web page, each data point will be coded in a way that computer programs will be able to understand and interpret. This next wave of technology change will lead us into the semantic web.

Web pages are generally coded using either HTML or the stricter XHTML markup languages (collectively known as X/HTML). However, these languages only tag data on the web page for presentation purposes (i.e. they say things like "make this word bold"), not for the actual meaning delivered by the content (they don't say "this word is the name of a city"). Using markup languages that code for meaning in addition to presentation will allow software to find and use specific bits of information on the web page, such as a date or a person's name, rather than just understanding everything on the page as one gigantic mass of text. Each bit becomes a separate piece of information with its own individual meaning. In some ways, the concept is like taking everything on the Internet and putting it into a gigantic database.

The real power of semantic markup, however, is that implicit relationships between bits of data can be established by the computer. People can read the text of two different web pages, for example, and be able to interpret implicit relationships between the data in each one. A computer cannot do this. If on one web page, a city is stated to be in a particular country and on another separate web page, a person is stated to be in that same city, then the implicit statement that the person is located in that same country can be understood easily by a person. Semantic markup will allow that implicit relationship to be also understood by a computer.

Underpinning the concept of the semantic web is the Resource Description Framework (RDF). RDF provides a structure to define an explicit connection between any two things. Currently, there are two basic methods to make RDF data available on the Internet. The first method is to create an external RDF document written typically as XML and that can be accessed and read by RDF-aware software. The second method is to extend the existing X/HTML coding of a web page using semantic tag attributes defined by one or more profiles, such as eRDF, RDFa or Microformats, and one or more descriptive vocabularies, such as Dublin Core (DC) or Friend Of A Friend (FOAF).

A software package designed to "understand" what the markup means will then be able to extract and use this tagged information. For example, a search engine designed to "read" the tags that indicate a person's name versus those that indicate a corporate entity will be able to distinguish between a web page containing biographical information about the person Abraham Lincoln and a web page for an elementary school named Abraham Lincoln. The embedded semantic markup is not visible to the naked eye. The person reading the marked up pages still sees just the text. The only way to see the semantic markup is to look at the source code for the web page. \

Semantic markup technology is still in its infancy. At this time, semantic markup of web resources is typically undertaken for a particular purpose and meeting particular requirements, such as a project to make specific resources available to OAIster. …

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