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Metadata
Registry
Registry is very important to the Metadata
mapping. To perform the mapping from one metadata to another,
both the names (or values) of elements should be contained
in a controlled vocabulary, where those values already
have been defined. The process of predefine the value
of all elements of one Metadata is called registration,
and the place (dictionary or authority file) to hold these
definitions is registry.
The registry describes the semantics, the
structure and the syntax of a Metadata element set it
holds. It may also include policies or recommended practice
for using the defined terms. By the use of registry, all
the Metadata schemas in the system are identified and
specified. It avoids the ambiguity of words existing in
different metadata, and provides the best mapping between
two types of Metadata. UKOLN Website contains several
Metadata Registries from different projects, such as DESIRE
Metadata Registry, ROADS,
and Dublin
Core Registry. Metadata.net
also collects nearly ten Metadata Schema Registries.
ROADS stands for Resource Organisation And
Discovery in Subject-based Services. The ROADS project
has several purposes:
- To produce a software package which can be used to
set up subject-specific gateways
- To investigate methods of cross-searching and interoperability
within and between gateways
- To participate in the development of standards for
the indexing, cataloguing and searching of subject-specific
resources
All Internet resources with different types
of format under one subject domain can be described by
different types of Metadata. Those Metadata are created
by ROADS templates. These templates consist of a set of
simple attribute-value pairs. ROADS use the WHOIS++
protocol to simultaneously search several databases. All
the templates ROADS uses are included in Metadata Registry,
and each template element is defined inside. Those Metadata
cover different types of data objects such as document,
dataset, image, and even another Metadata schema, e.g.
Dublin Core.
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