W3C Search, PICS

Catalogs: Resource Description and Discovery

Information retrieval techniques span a spectrum from full-text search, which is a high-recall technique which makes little demand on the information representation, to knowledge-base query, which is a high-precision technique, which depends on a rich information representation.

Catalogs are databases structured for the purpose of browsing, searching, and generally organizing large volumes of related data, or more often: metadata. see also: design issues, where TimBL is writing about metadata again. 97-02-07 connolly

Metadata has two main functions:
WAIS through the Web - About Metadata

A catalog records is generally not a primary resource, but rather a surrogate, excerpt, abstract, or description giving some attributes of another resource. The question arises: whence comes the list of attributes? What's the expressive capability, structure, and meaning of attribute values?

A PICS label represents a set of category/value pairs, where the categories are part of a globally unique rating system. (While PICS 1.1 allows only for floating point values, an enhancement to accomodate string values is expected.)

PICS categories can serve as metadata attributes. Their meaning is given in the rating system. The structure of a PICS label is similar to:

Describing and Linking Web Resources for an architectural description of this metadata structure.

More complex structures can be accomodated by PICS extensions:

Resource Description in HTML


Related Resources

At W3C

Catalog Numbers: URNs
along with payment and copyright enforcement mechanisms, these can be used to meet Engelbart's Library requirement
Applying Harvest in the Davenport Group
an example of using domain experts to increase link reliability

On the Web

CIT's Work on Smart Catalogs and Virtual Catalogs.
Universal Resource Characteristics (URCs)
HyperNews collection by Michael Shapiro and Dan LaLiberte
The Harvest Information Discovery and Access System
A Format for E-mailing Bibliographic Records
KQML - Knowledge Query and Manipulation Language
ARPA Knowledge Sharing Effort public library

Research Notes

WEBDAV Meeting Notes:

Comment:  So you will have to encode binary data? This is

          Response: Focus on the object-model. Is it complete? Consistent?
                    Web Collections are just a convenient vehicle for
                    expressing the object model; if there is a better way
                    of expressing the model, we'll use it.
          Question: Who manages the link "types" (e.g., registration)?
          Answer:   Core link types ("core" to implementing WEBDAV) are
                    defined in the specification. Other "types" owned and
                    managed various groups (e.g., Dublin Core). Namespace
                    convention for link types is schema.(schema.type).
          Response: Take care! Define namespace requirements for links so
                    that WEBDAV complies with the "Schema" work group
                    (Chris Weider, Chair).

          Comment:  Why be non-extensible w.r.t. the link definition? Allow
                    other fields to be added to the core fields (source,
                    dest, type).
          Comment:  PICS is doing meta-data. The authors would be well
                    advised to look at the PICS effort.


Consumers of metadata collections

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