W3C has acknowledged receipt of a member submission entitled XML Schema API. The technology was submitted by from IBM Corporation and X-Hive Corporation B.V. and provides API access to properties of the XML Information Set.

Specifically, the document "defines an XML Schema API, a platform- and language-neutral interface that allows programs and scripts to dynamically access and query the post-schema-validation infoset (PSVI) defined in the Normative Appendix C (Outcome Tabulations) of the W3C Recommendation XML Schema Part 1: Structures, "C.2 Contributions to the post-schema-validation infoset." The specification is implemented in Apache Xerces2 Java Parser; there is also a C++ binding and implementation for this specification in Apache Xerces C++ Parser."

Section 1.2 defines interfaces which allow developers to access the XML Schema components which follow as a consequence of validation and/or assessment; Section 1.3 defines a set of interfaces for accessing the PSVI from an instance document; Section 1.4 defines a set of interfaces for loading XML Schema documents.

The W3C Staff comment on the XML Schema API notes that the proposal "provides a substantial and useful addition to the DOM API, or to other existing event/pull parsing APIs such SAX/XNI. However, the XML Query and XSL Working Groups have been working on extending the work of XML Schema and adding more properties, and are working on a new version of XML Schema 1.1; therefore, while the proposal addresses today's needs, it should be noted that future extensions will still be needed to follow additions to the XML Architecture."

Bibliographic Information

XML Schema API. W3C Member Submission. 22-January-2004. Submitted by IBM and X-Hive on 9-December-2003. Published on 22-January-2004. By Elena Litani (IBM). Version URL: http://www.w3.org/Submission/2004/SUBM-xmlschema-api-20040122/. Latest version URL: http://www.w3.org/Submission/xmlschema-api/. Copyright (c) 2002-2003 International Business Machines Corporation.

From the W3C Staff Comment

"The XML Schema API allows applications to access:

• the representation of the XML Schema Components represented into a set of XML Schema documents, as defined in Schema Component Details (XML Schema Part 1: Structures, Section 3). This also includes access to the data types, defined in XML Schema Part 2: Datatypes
• the information resulting from the processing of a set of XML Schema documents against an XML document. Applications can therefore access the XML Schema extensions of the XML Information Set (Infoset), called Post-Schema Validation Infoset (PSVI), as defined in "Contributions to the post-schema-validation infoset" ([XML Schema Part 1: Structures], Appendix C.2).

The PSVI interfaces proposed take advantages from an interface listed in the DOM Level 3 Core specification (DOMConfiguration). They can be accessed when manipulating DOM nodes... or streaming or pull oriented solutions such as SAX or XNI. Finally, the design on the API follows the path of the DOM API and uses the OMG IDL to remain language and platform neutral.

While DOM Level 3 Core does provide better access than DOM Level 1 or 2 to the properties of the XML Information Set, it does not provide access to the extension defined in the XML Schema specification. Given the wide use of XML Schema, the proposal provides a substantial and useful addition to the DOM API (or other existing event/pull parsing APIs such SAX/XNI). However, the XML Query and XSL Working Groups have been working on extending the work of XML Schema and adding more properties. The XML Schema Working Group is also working on a new version of XML Schema 1.1; see Requirements for XML Schema 1.1. Therefore, while the proposal addresses today's needs, it should be noted that future extensions will still be needed to follow additions to the XML Architecture. Alternative approaches to the problem of Infoset extensions are possible, each of them having their pros and cons..."

The submission will be brought to the attention of the XML Schema Working Group, W3C's AC and the community at large. Past discussions failed to bring consensus around a common solution for an API for XML Schema, and it is not clear that the efforts would gain interest from a significant portion of the XML Schema companies and their users.