This paper is a follow-on from the broader paper presented at the XML Europe 2003 conference entitled "The emergence of ASN.1 as an XML schema notation". That paper described the use of ASN.1 as an XML schema notation, and briefly mentioned a standardised mapping from XSD into ASN.1 notation.

ASN.1 is a mature notation for specifying the content of messages and their encoding which was first standardised by ITU-T and ISO in the early 1980s. It concentrates on the specification of the information content of a document, not on its syntax. It has recently been extended by the standardization of a mapping from W3C XML Schema (and with XML encoding rules). This was presented in outline in the earlier paper.

The standardization of the mapping from XSD (and the emergence of supporting tools) enables the mature and standardised (in ISO and in ITU-T) ASN.1 binary encoding rules to be applied to XML documents defined using XSD (as well as to those defined using ASN.1 directly as the XML Schema notation).

The ASN.1 encoding rules include canonical encodings that are suitable for use in security work such as digital signatures. The "Distinguished Encoding Rules" are used in X.509 Certificates, but there are Canonical Packed Encoding Rules also available with the same canonical properties, but providing greater compression.

The presentation will describe the pieces of standardization that are involved and their relationship, and will include a demonstration of the use of standards-based tools to:

- Take as input an (arbitrary) XSD specification and generate a complete XML-binary-conversion application.

- Input to the application an XML document conforming to the XSD specification, producing output which is a compact binary representation of the information content of the XML document using a standardised encoding, and suitable for transmission over a low-bandwidth carrier such as a wireless network.

- Input to the application of the compact binary representation to reproduce the original XML document.

Figures will be provided for the amount of compaction that is achieved for a range of test cases, together with comparisons of the compactness of the ASN.1 binary encoding of the XML content with other means of providing binary encoding of XML, for example binXML.

The presentation will be of interest to a technical audience that is concerned with efficient transmission of XSD-defined XML documents over low-bandwidth carriers such as radio networks, although the level of presentation will attempt to avoid technical details of the actual encoding.