Re: Representation of OIDs as URIs

Karl Scheibelhofer wrote:
> 
> in the last ETSI ESI meeting we discussed how we could represent OID (ASN.1)
> as URIs. i proposed two schemes that seem reasonable. we would also like to
> hear other opinions.
> these two approaches are as follows:
> 
> One encodes the OID as an URL and the other encodes it as an URN:
> 
> ·       Encoding as URL:
> fix a base URL and append the OID in an appropriate format (human readable)
> e.g.,
> http://www.etsi.org/oid/itu-t(0)/identified-organization(4)/etsi(0)/electron
> ic-signature-standard(1733)/part1(1)/idupMechanism(4)/etsiESv1(1)

You should only use the number form such as in:
http://www.etsi.org/oid/0/4/0/1733/1/4/1
because the name form is not mandatory and synonyms can sometimes exist.

Of course, this is not readible but you could define aliases at each level of
the registration tree as I did on the ASN.1 website
<http://asn1.elibel.tm.fr/oid/>. This would allow you to write things like:
http://www.etsi.org/oid/itu-t/identified-organization/etsi/electronic-signature-standard/part1/idupMechanism/etsiESv1

> The generated URL must be persistent! This means that the resulting URL must
> not be used to identify anything else than this OID. And this should be the
> case, at least as long as this URL is used to identify this OID.
> Advantages and disadvantages of this approach that we are aware of by now,
> are as follows.
> Advantages:
> +       Uses the widely know schema of URLs.
> +       The owner of the OID can place a specification document at the place on
> his web server this URL refers to.
> +       If there is no resource (e.g. a specification) at the given URL, then it
> is just a unique name like an OID is.
> +       Every company can use its own base URL. Some people also mentioned the
> idea to use one base URL for all OIDs (e.g. http://www.w3.org/oid/,
> http://www.oid.int or http://www.iso.org/oid).

You could also use http://asn1.elibel.tm.fr/oid/

> This would have the advantage
> to have always the same base URL. The disadvantages would be: If the owners
> want to place a specification on the web server, the owning company would
> have to maintain web space for all OID owners (perhaps a redirection
> mechanism would solve this?).

The ASN.1 website allow people to add their arc (identifier + number) to
the view of the registration tree that is provided. Of course, the material
is validated before appearing on the website to avoid bad use of the tool,
but we tried to provide an easy-to-use feature (when filling the form,
you can indicate URLs where other information/spec./documents can be
found).

> Additionally, if a company wants to use this
> base URL for internal (or even secret) purposes, it might not want to use
> the fixed base URL (perhaps, it could just use anyone, if it is just for
> internal use?)

This company can at least register its arc by using its number form (but not
using its name form if the company thinks that it is confidential).

> Disadvantages:
> -       The company owning the domain name of the base URL must ensure that the
> base URL is persistent. It needs to be persistent as long as there is one or
> more URLs in use for identifying an OID using this base URL. Remind that the
> base URL includes the domain name and any additional directories.

Yes, and legal things should also be checked.

> -       If the URL is used just as a unique name without referring to any
> resource, it might confuse people.
> 
> ·       Encoding as URN:
> register a NID (see RFC 2141 and RFC 2611) through IANA
> (http://www.iana.org)
> e.g., register “oid” as an NID, define NSS to identify an ASN.1 OID. This
> could look like
> urn:oid:itu-t(0)/identified-organization(4)/etsi(0)/electronic-signature-sta
> ndard(1733)/part1(1)/idupMechanism(4)/etsiESv1(1)
> for instance.

There is a draft RFC (the author was Meallow if my memory serves me right)
that addresses the translation of OIDs into URNs. I sent comment to the
authors and proposed him to implement an OID-to-URN translator on the
ASN.1 web site, but I don't know what is the status of is document now.
-- 
Olivier DUBUISSON
france telecom R&D
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Received on Friday, 24 November 2000 12:01:52 UTC