OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.


Help: OASIS Mailing Lists Help | MarkMail Help



   Re: XML encoding ASN.1 (was Re: Another Question)

[ Lists Home | Date Index | Thread Index ]
  • From: "Peter Jacobi" <pj@walter-graphtek.com>
  • To: Olivier.Dubuisson@francetelecom.fr
  • Date: Thu, 22 Jun 2000 16:09:33 +0200

Olivier, All,

> > a) use the tags as element names ("A17" for [APPLICATION 17]),
> > use fixed attributes for identifiers and data type names.
> Tags are historical "residues" in ASN.1. They are only used by the
> BER encoding rules.
> It is now recommended to add the "AUTOMATIC TAGS" clause in the
> module headers and to not take core of the tags any more.

Even when AUTOMATIC TAGS  is used, each element has a tag. 
And there seems to be an argument for tags, as can be seen by the wide 
selection of file formats using some sort of tagging, to be extensible (e.g. 

> > b) use the identifiers as element names, use fixed attributes for tags
> > and data type names.
> What's the need to keep the tags and type names? It seems to me that
> this verbosity is useless.

In the normal case, no verbosity is involved, as fixed attributes aren't 
transmitted in the document instances.

> Do you make the assumption that both sides (i.e., the encoder and the
> decoder) are generated from the same ASN.1 module? 

Yes, but I want to be prepared for extensions. That's the main reason 
you cannot drop the tag, as that would prohibit round-tripping BER-

The original sender may use a special tag value to insert an element into 
a SEQUENCE. You must keep this tag value in the XML encoding for the 
sahe of re-producing a BER encoded version.

Peter Jacobi

This is xml-dev, the mailing list for XML developers.
To unsubscribe, mailto:majordomo@xml.org&BODY=unsubscribe%20xml-dev
List archives are available at http://xml.org/archives/xml-dev/


News | XML in Industry | Calendar | XML Registry
Marketplace | Resources | MyXML.org | Sponsors | Privacy Statement

Copyright 2001 XML.org. This site is hosted by OASIS