Meta Data

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Metadata is structured data about data. Metadata usually describes some object or resource with the aim of improving a machine's understanding of it.

Metadata standards

A number of different metadata proposals and standards have arisen, which reflect ongoing research in this area and the various and diverse applications of metadata.

Attribute based metadata standards provide a method of assigning attributes (or properties) to a resource.

Attribute-based metadata allows simple statements to be made about resources. Object-based metadata provides more flexibility.

Where is Metadata stored?

Metadata is usually associated with a resource using one of two methods:

  1. Distributed: metadata is stored alongside the resource it describes. Metadata standards such as HtmlMetaTags may even require the metadata to be embedded within the resource.

    • Advantage: Each resource (and its metadata) is a self-contained unit.

    • Disadvantage: Increased maintenance overheads - metadata has to be collected from many locations, and any changes to the representation must be made to all effected metadata.

  2. Centralised: metadata is stored separatly from the resource it describes, in a central repository.

    • Advantages:

      • A central repository offers greater maintainability than a distributed approach.

      • Easier for search engines and indexers to process the metadata - all in one place.

      • All metadata represented using same standard.

    • Disadvantages:

      • If repository is overlooked by search engines and indexers, large loss.

      • In an environment with a large collection of unrelated metadata authored by many users, the successful integration of diverse users and metadata representations into a single repository is likely to fail. A community-driven distributed approach may be more practical.

See Also:

  • SemanticWeb

  • W3C Metadata Activity [1] (now superceded by the W3C Semantic Web Activity [2])


-- Last edited October 27, 2002

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