XPackage: RDF/XLink-based packaging format

["Garret Wilson" <garret@globalmentor.com>]

xml-dev Members (and www-xml-packaging members, who have seen very early
versions of this specification),

As a member of the Open eBook Forum (OEBF) ( www.openebook.org ), my company
has been working on ways to package eBook material such as XML documents,
stylesheets, metadata, images, sound files, etc. The original OEB packaging
method, introduced in the Open eBook Publication Structure 1.0, was very
specific to eBooks. As the OEBF works on OEBPS 2.0, we're realizing that a
more generalized packaging mechanism is necessary. This is consistent with
the aims of the W3C Packaging Working Group formed several years ago, which
never received enough interest to be able to sustain its work.

The use cases of an XML-based packaging format include:

* Specifying which resources might be bundled and transported together.

* Specifying which resources are stylesheets of XML documents, and doing so
*outside* the actual XML document to which the style is being applied.

* Specifying metadata of a resource.

* Indicating alternate resources for fallbacks (i.e. different image
resolutions, unsupported types).

* Specifying how resources should be relationally organized for later
retrieval.

* Specifying the content type, Unicode code points, and other information
about a resource.

The OEB Publication Structure Working Group has decided to create a new
packaging format for use in OEBPS 2.0. Instead of simply extending our old
package format, we're creating a new generalized packaging format, currently
named XPackage. The OEBPS 2.0 package will be an application of the more
general XPackage.

Realizing that many items that need to be specified in a package are in
essence metadata, we were able to leverage the W3C Resource Definition
Framework for a package description. The current XPackage draft uses a
subset of the RDF model and syntax. This means that an RDF processor can
process an XPackage instance in the same way it processes RDF/XML Dublin
Core and other RDF-based metadata, resulting in a consistent interlinking
graph of all package resources and their properties.

The current XPackage draft, which I'll be attaching to a separate e-mail, is
nearing feature-completeness but has not been through a rigorous round of
editing and wordsmithing. The OEB PS WG is only now beginning to discuss the
specific property and serialization aspects of XPackage, but we expect it to
follow the framework present in the current draft.

The OEB Publication Structure Working group values any comments you may have
about our current XPackage draft, and we would welcome anyone who wants to
participate more closely with the OEBF as we complete this specification.

Sincerely,

Garret Wilson
President, GlobalMentor, Inc.
Member, Open eBook Forum