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The specification for esXML has been updated significantly. The current
specification includes the ability to be tuned for processing,
compactness, and processing+compactness optimized application
scenarios. Several innovative ideas are included, especially the
MetaStructure Instance (MSI) representation of information that is
"externalized" from a "complete" instance of a data object.
esXML supports documents or objects that are any place on a spectrum
from self-contained and self-describing (a la text-based XML, with or
without a schema) to a fully-externalized data representation. The
latter externalizes various typing, structure, and metadata into an MSI,
leaving a highly compact and optionally compressed instance, similar to
PER encoding. One ore more MSIs + a referring instance are equivalent
to a self-contained, self-describing instance. This mechanism helps
unify the various styles of data encoding under a theoretical framework,
referred to as "externalization", for thinking about what is or is not
present in an instance. In many legacy cases, for instance, knowledge
about the structure of an instance is embedded in the actual code that
knows how to interpret it. This is important when comparing various
approaches to general purpose data representation.
The MSI is designed to allow any template, schema language, or automated
encoding design process to produce metadata that any encoder and decoder
can use to access or convert data. This allows both the specification
and codecs to be simplified while allowing the use of schema-based
encoding that can evolve independently.
Comments, discussion, and collaborative development are welcome.
Stephen D. Williams
http://sdw.st firstname.lastname@example.org email@example.com