Prepress Technology March 2000
I never metadata I didn't like: Speaking the language of digital assets
By Sebastian Holst
Special to Newspapers & Technology
There is now a wealth of information on every subject available on the Internet. For many, however, the true excitement of the Web is in the services that you can access from your home or office. Users can purchase books, computers, and any number of other items.
The possible uses of the Web seem endless, but today the Web is still missing a crucial piece. Missing is a part of the Web that contains information about information -- labeling, cataloging and descriptive information that allows Web pages to be properly searched and processed in particular by any computer anywhere in the world. In a word, the Web needs metadata.
Metadata and its use in computing is not new, but its use in the emerging digital society deserves close inspection. When you're done reading this article, you should understand what metadata is, how it is being used, why, and finally, how Internet standards like XML are simplifying all of the above.
Metadata is easily defined as "data that describes data." For example, a library catalog contains information (metadata) about publications (data) and a file system maintains permissions (metadata) about files (data).
There are many metadata initiatives on the Web. The Wireless Application Protocol is metadata that will make it easier for you to use your cellular phone as a portal onto the Internet. The Information Content and Exchange protocol is metadata that defines the roles and responsibilities of syndicates and subscribers and their shared content. These are examples of special-interest metadata. In other words, this is metadata that is only understood by a community with common interests, e.g. the wireless and publishing industries.
Other metadata initiatives include the World Wide Web Consortium's Resource Description Framework and its relative Platform for Internet Content Selection. These are metadata frameworks designed to provide more generic information about information. In theory, all programs working over the Web could interpret and process PICS- and RDF-compliant metadata.
How is a program to know which metadata model it is processing? The answer -- hopefully -- is XML (eXstensible Markup Language).
XML is not your typical computer language. It is a metalanguage. Recall that metadata is data that describes data. A metalanguage is a language that describes other languages. As a metalanguage, XML is used to describe other languages. The forums and consortia that are developing metadata for the Web are almost universally using XML to define their metadata. This provides a common platform for programs to "sniff out" what metadata framework is being used before interpreting specific data values. Voila! Interoperability is at hand.
In summary, metadata tells a program about data. This is important for searching and processing diverse kinds of data. The Web's ubiquity has escalated the need for metadata. Sometimes the need is very specialized and relevant to a specific community and sometimes metadata is used to homogenize and integrate vast amounts of "generic" data.
While not required, the use of a broadly understood metalanguage, like XML, speeds adoption of metadata and reduces the possibility for confusion and unexpected behaviors.
The Web may be the reason you are being forced to confront these concepts today, but the difficulties of describing information have been debated for thousands of years, as Aristotle himself confirms: "A real man and a figure in a picture can both lay claim to the name ëanimal'; yet, though they have a common name, the definition corresponding with the name differs for each."
Sebastian Holst is the vice president of marketing for Artesia Technologies -- supplier of the TEAMS enterprise digital asset management solution. He also serves as Artesia Technologies' representative to the W3C's Advisory Committee. He can be reached at sebastian.holst@artesiatech.com.