COMMITTEE T1 – TELECOMMUNICATIONS
Committee T1M1.5   
T1M1.5/2001-034

Phoenix AZ; February 26 to March 2, 2001

 

Contribution

 

TITLE:                           ASN.1 use of XML, Encoding Control Notation, Tools and books on ASN.1

SOURCE*:                   ITU-T SG7, WorldCom

PROJECT:                  

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ABSTRACT

 

The ASN.1 standards group has made much progress in enhancing ASN.1 to allow its use in support of legacy applications, and to allow XML browsers to be used to easily display values of types defined using ASN.1.  Work is also underway to allow messages described using XML to be converted to ASN.1, thereby circumventing the verbosity of XML encodings and allowing them to be encoded very compactly.  In conjunction with this work, ASN.1 tools are under development to support these new notations

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*See contacts below

Uploaded by Ed White, WorldCom, +1.972.729.5509, ed.white@wcom.com
ITU - Telecommunication Standardization Sector
   Temporary Document 2017/Rev.2

STUDY GROUP 7     

 

Geneva, 29 January - 2 February 2001

 

 

Question(s): 9/7

 

 

SOURCE*:            Q.9/7 RAPPORTEUR

 

TITLE:            ASN.1 use of XML, Encoding Control Notation, Tools and books on ASN.1

_____________

 

LIAISON STATEMENT

TO:             ALL ITU-T SGs,
BOS (Business Object Summit),
T1M1 (Internetwork, Operations, Administration, Maintenance, and Provisioning)

 

APPROVAL:          ITU-T Study Group 7

 

FOR:          Information

 

*CONTACT:                        Olivier Dubuisson                        Tel:                        +33 2 96 05 38 50

France Télécom R&D          Fax:          +33 2 96 05 39 45

          Email:          Olivier.Dubuisson@francetelecom.com


The ASN.1 standards group has made much progress in enhancing ASN.1 to allow its use in support of legacy applications, and to allow XML browsers to be used to easily display values of types defined using ASN.1.  Work is also underway to allow messages described using XML to be converted to ASN.1, thereby circumventing the verbosity of XML encodings and allowing them to be encoded very compactly.  In conjunction with this work, ASN.1 tools are under development to support these new notations.

 

 

1                   Displaying ASN.1 messages using XML browsers

 

The ASN.1 standard is being enhanced to provide a standard mapping of values of types defined using ASN.1 into XML markup format, making it possible for such values to be easily displayed using common XML browsers regardless of which encoding rules (e.g., BER, PER) such messages were encoded in.  This is being achieved by using ASN.1 as the schema of the messages, and XML markup as the display format. 

 

In addition to the enhancements to the ASN.1 standard, a new encoding rules document, ITU-T Rec. X.693 | ISO/IEC 8825-4, titled "Encoding using XML or basic ASN.1 value notation", is being created.  This document specifies how to encode values of ASN.1 types in XML markup format for the purpose of transmission (as opposed to using XML markup as value notation within an ASN.1 module).  Also specified in this document is how to encode values of ASN.1 types using ordinary ASN.1 value notation for the purposes of transmission.

 

Some benefits of this work are:

 

–                     Applications will be able to easily display BER-encoded or PER-encoded messages (for example) using XML browsers.

–                     It makes possible the creation of tools that allow applications to encode messages in XML markup format, BER format, PER format, etc., without the need to know the details of how to encode values in any of these formats.

–                     It will be possible for application protocols to exploit the ASN.1 value notation as an ordinary set of encoding rules in those cases where textual encodings are desired but there is no interest in using XML markup.

–                     Used in conjunction with the ECN support (explained in Section 3), this also enables legacy protocols to have their values displayed using XML.

 

A free ASN.1 syntax checker which supports XML markup will be made available at http://www.oss.com in the September 2001 timeframe.  Commercial versions of ASN.1 products with XML markup support will start to become available in the same timeframe.

 

 

2                   Encoding XML-defined messages using ASN.1

 

An additional encoding rules document, ITU-T Rec. X.694 | ISO/IEC 8825-5, titled "Encoding XML-defined data using ASN.1", is being created.  This document specifies a standard mapping of XML Schemas into ASN.1, exploiting ASN.1 to produce much more compact messages than what is produced by XML markups.  The main benefit of this is that applications such as WAP, SyncML, VoiceXML, etc, that use XML to describe their messages will be able to encode them much more compactly than is possible with current binary XML encodings.

 

 

3                   Use of ASN.1 to support legacy protocols

 

A new notation defined in ITU-T Rec. X.692 | ISO/IEC 8825-3, titled "Specification of Encoding Control Notation (ECN)", has been defined to:

 

–                     allow ASN.1 types to be defined for established ("legacy") protocols where the encoding is already determined and differs from any standardized encoding rules (e.g., BER, PER), and

–                     allow protocol specifiers to create encodings that are minor variations on standardized encoding rules.

 

Since both ASN.1 and ECN specifications are machine processable, encoders and decoders can be automatically generated from them.  This is a significant factor in reducing both the amount of work and the possibility of errors in making interoperable systems.  Another advantage is the ability to provide automatic tool support for testing.

 

A free ASN.1+ECN syntax checker will be made available at http://www.oss.com in the September 2001 timeframe.  Commercial versions of ASN.1+ECN toolkits will become available in the same timeframe.  More information on ECN, including a tutorial, can be found at http://asn1.elibel.tm.fr/ecn.

 

 

4                   Assistance on ASN.1 and ECN

 

Members of the ASN.1 standards group frequently assist application standards groups in their use of ASN.1 and ECN.  Such assistance ranges from review of ASN.1 specifications for correctness and recommendations on best use practice, to teleconference or in-person participation in application standards meetings.  If you require assistance in use of ASN.1, ECN or XML issues related to ASN.1, please contact the ITU-T ASN.1 Rapporteur, Olivier Dubuisson <Olivier.Dubuisson@francetelecom.com> or the ISO/IEC ASN.1 Rapporteur, John Larmouth <J.Larmouth@salford.ac.uk>.

 

Study Groups that might be interested in this support include those whose experts are:

–           Existing or new users of "traditional" ASN.1 (no ECN, no XML).

–           Maintaining or extending protocols that are not currently defined using ASN.1, but that want to enhance tool support for their protocols by using ASN.1+ECN.

–           Defining new protocols that wish to use ASN.1, but that wish to use ECN to provide control over the encoding of some parts of the protocol, or of extensibility mechanism.

–           Wish to provide XML documents from existing ASN.1 definitions.

–           Are defining their protocols as the transfer of XML documents (defined using XML schema), but wish to allow more efficient transfer of XML data using ASN.1 encoding rules.

 

5                   Free books and tools on ASN.1

 

You can obtain free copies of electronic books on ASN.1:1997 and free copies of ASN.1:1997 validation tools from the http://asn1.elibel.tm.fr and http://www.oss.com web sites.  Additionally, a list of commercial and freeware ASN.1 products can be found at http://asn1.elibel.tm.fr and http://www.asn-1.com.