Deployment and Support of XML 1.1

The XML Protocol Working Group would like to call the attention of the 
TAG and XML Co-ordination Group to the issues we've encountered 
regarding the use of XML 1.1.

Recently, the Working Group decided to limit the payload of SOAP 1.2 
envelopes to those XML Infosets that can be serialised using XML 1.0. 
In other words, while a binding can use XML 1.1 to transport a SOAP 1.2 
envelope, no SOAP 1.2 envelope can take advantage of any of the parts 
of XML 1.1 that mandate a change in the Infoset (e.g., 
internationalised element and attribute names, extra characters).

The primary reason for this difficult decision was XML Schema's 
inability to describe XML 1.1 constructs; because there are normative 
constraints reflected in our Schema, we felt it unwise to make it 

In the Working Group's view, this highlights a growing misalignment in 
the XML architecture. Until the advent of XML 1.1, XML 1.0 was a single 
point of constraint in the XML stack, with all of the benefits (e.g., 
interoperability, simplicity) that implies. Because XML 1.1 has 
introduced variability where before there was only one choice, other 
standards now need to explicitly identify what versions of XML they are 
compatible with. This may lead to a chicken-and-egg problem; until 
there is a complete stack of XML 1.1-capable standards available, it is 
problematic to use it.

Furthermore, XML-based applications will likewise need to identify 
their capabilities and constraints; unfortunately, there is no 
consistent way to do this in the Web architecture (e.g., RFC3023 does 
not provide a means of specifying XML versions in media types).

As a result, we urge the TAG and XML Co-ordination group to carefully 
consider what mechanisms are necessary to support XML 1.1, how XML 
1.1-based standards should be packaged and presented by the W3C, and 
whether the benefits of a single point of constraint on the XML 
architecture can be re-introduced.

On behalf of the XML Protocol Working Group,

Mark Nottingham   Principal Technologist
Office of the CTO   BEA Systems

Received on Wednesday, 19 May 2004 13:23:48 UTC