Subject: RelaxNG examples

From: Simon Leinen <[email-masked]>
Date: Wed, 8 Nov 2006 02:20:56 +0100

On the ad-hoc meeting on data modeling issues, the possibility of
using RelaxNG for data modeling work was raised, and some people asked
for examples.  Here are some that are somehow related to network
management.

The Compact RelaxNG Schema for NETCONF's protocol operations (at the
time) that Rob Enns posted to the list in November 2004:

  http://ops.ietf.org/lists/netconf/netconf.2004/msg00597.html

The (Expired) draft-schoenw-nmrg-snmp-measure-01.txt contains a
RelaxNG schema for a set of information from SNMP packet traces:

  http://bgp.potaroo.net/ietf/all-ids/draft-schoenw-nrmg-snmp-measure-01.txt
-- 
Simon.

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---

From: Hideki Okita <[email-masked]>
Date: Thu, 09 Nov 2006 01:44:23 +0900

From implementors' viewpoint,
RelaxNG as the schema is not a good choice.

Major development environments such as Java (Apache),
Visual Studio and others has no support for RelaxNG.

Surely RelaxNG make it easy to read "directly" the NETCONF schema.
However, finally, it can decrease the development efficiency.

I do not object to use RelaxNG as the optional means.
However, XSD should remain as the default schema in NETCONF drafts.

Best regards,

Hideki Okita
Hitachi, Ltd.

References:

RelaxNG Homepage:
http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=relax-ng

Apache Xerces2 Java Parser Homepage:
http://xerces.apache.org/xerces2-j/

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From: "David T. Perkins" <[email-masked]>
Date: Wed, 8 Nov 2006 09:02:21 -0800 (PST)

HI,

Aren't there tools that can convert a RelaxNG document to
an XSD document? If so, would this satisfy your needs?

Regards
/david t. perkins

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From: Yoshifumi Atarashi <[email-masked]>
Date: Thu, 09 Nov 2006 02:25:05 +0900

I think there are a few style decision points.

1) expression ability
2) easy to understanding
3) programming language/tool/library support
4) capability

In my understanding,
RelaxNG
1) good
2) good
3) not good
4) not good, because RelaxNG is not mainstream in XML tool developer.
   (Our XML expert told us.)

xsd
1) good (a little limited)
2) good (a little limited)
3) very good
4) good

So I think we choice "xsd", for operator who can make netconf tools and
NMS programmers.
-------
   Yoshifumi Atarashi

---

From: Hideki Okita <[email-masked]>
Date: Thu, 09 Nov 2006 02:57:46 +0900

David,

Thanks for your comment.

I know that there is some tool to convert a RelaxNG schema to a W3C XML 
Schema.
For example, "relaxer" (http://www.relaxer.org/) may have this function.

However, such conversion function does not support full features of 
RelaxNG and XSD.
Implementors should adjust the gap and check its consistency by themselves.
It increases development costs.

Regards,

Hideki Okita

---

From: Juergen Schoenwaelder <[email-masked]>
Date: Wed, 8 Nov 2006 20:55:10 +0100

> So I think we choice "xsd", for operator who can make netconf tools and

I assume that all sensible developers will use some other input format
to generate the XSD. And I doubt the IETF has enough people who can
really read and judge the correctness of XSDs - at least this WG seems
to have proven that bugs in the XSD usually stay around for a long
time undetected (even though there are all these great tools out
there).

/js

-- 
Juergen Schoenwaelder		    International University Bremen
<http://www.eecs.iu-bremen.de/>	    P.O. Box 750 561, 28725 Bremen, Germany

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From: Andy Bierman <[email-masked]>
Date: Wed, 08 Nov 2006 12:25:57 -0800

> 2) good (a little limited)

I do not rate XSD ease-of-understanding as good.
I rate it as awful, even unacceptable.
Human factors are very important here because humans, not machines,
need to understand the data models that are being proposed and
developed for standardization in IETF WGs.

IMO, most of the humans working in the NETCONF WG do not understand XSD
well enough to throw down hill 5 feet.  This is a significant
process problem, since it is difficult to reach consensus
on complex technical details if very few people actually
understand what they are reading.

A comment was made at the data modeling meeting that W3C is now
doing development in RelaxNGc, and converting it to XSD for normative
reference in the final standard.  How clueful.  How about if we do
the same thing?  We don't care if the conversion isn't pretty.
(Nothing about XSD is pretty, so it's a non-issue. ;-)

Note that there is no guarantee that people will understand
RelaxNG either, but most people find it more readable and writable
than XSD.

Andy

---

From: Yoshifumi Atarashi <[email-masked]>
Date: Thu, 09 Nov 2006 07:09:42 +0900

> time undetected (even though there are all these great tools out

I think so. Developers usually use tools(eclipse and so on).
--------------
  Yoshifumi Atarashi

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From: Hideki Okita <[email-masked]>
Date: Thu, 09 Nov 2006 07:35:13 +0900

Andy,

Thanks for your comment.

As I said in the first mail, I agree that XSD is difficult
to read "directly".

Normally, to develop applications using XML data, developers
at first construct classes and generate XSD description from
these classes by some XSD generation tool.
In addition, they use GUI to draw classes and XSDs.

And, when they include and validate the XML schema like the
NETCONF protocol schema, they use integrated development
environment (IDE). They do not read directly the XML schema.

Which expression is best for the WG documents?
Do not we need to write drafts more visually?

Best regards,

Hideki Okita

---

From: Andy Bierman <[email-masked]>
Date: Wed, 08 Nov 2006 15:06:07 -0800

> Do not we need to write drafts more visually?

I am not comfortable with the idea of standardizing text that
many people to not "directly" understand, and just trust that
all toolmakers will get everything exactly right and exactly
the same.  I don't use a GUI tool to write XSDs. Is the IETF
going to mandate that I use some tool, just like it is
effectively mandated that xml2rfc be used to produce an
Internet draft?

Andy

---

From: Juergen Schoenwaelder <[email-masked]>
Date: Thu, 9 Nov 2006 01:46:46 +0100

> environment (IDE). They do not read directly the XML schema.

So why tend our schemas to be buggy?

And how does party A who uses tool X effectively communicate with
party B who uses tool Y? Standards establish a common language and
therefore the artefacts must be human readable. The IETF works by
exchanging text fragments, not screen shots.

/js

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From: Andy Bierman <[email-masked]>
Date: Wed, 08 Nov 2006 17:35:55 -0800

> exchanging text fragments, not screen shots.

Even if there was a magic perfect tool that could be relied
on for decades to come, that only solves part of the problem.

It's one thing to validate a schema for XML correctness.
It's quite another to validate that the schema actually
represents what the protocol designers intended it to represent.
We've been having difficulty with both types of errors.
In the latter stages, we saw mostly the latter type,
but some type 1 errors were found in IESG review
(the last place errors like that should be detected in our process).

This isn't just about the XML.
This is about an ongoing and evolving standardization process.
It's a much harder problem.

Andy

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From: Balazs Lengyel <[email-masked]>
Date: Thu, 09 Nov 2006 09:35:19 +0100

Hello,
As I heard the mainstream tool converting relax to xsd is trang which is freeware.
http://www.thaiopensource.com/relaxng/trang.html
Balazs

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From: "tom.petch" <[email-masked]>
Date: Thu, 9 Nov 2006 14:38:28 +0100

----- Original Message ----- 
From: "Juergen Schoenwaelder" <[email-masked]>
To: "Yoshifumi Atarashi" <[email-masked]>
Cc: <[email-masked]>; "Hideki Okita" <[email-masked]>
Sent: Wednesday, November 08, 2006 8:55 PM
Subject: Re: RelaxNG examples

> time undetected (even though there are all these great tools out
Is there a publicly available tool for XSD like
  [email-masked]
or its successor is for SMIv2?

Tom Petch

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From: Phil Shafer <[email-masked]>
Date: Thu, 09 Nov 2006 11:05:51 -0500

>time undetected (even though there are all these great tools out

Amen to that.  The value of tools that grok XSD is eclipsed by the
hardship humans have grokking it.  And the availability of tools
doesn't guarantee to their use.  I know Rob pulled out the XSD
snippets from the spec and validated them, but the presence of bugs
shows this wasn't enough to guarantee correctness.

Thanks,
 Phil

---

From: "David B Harrington" <[email-masked]>
Date: Wed, 15 Nov 2006 19:16:44 -0500

Hi Simon,

There was discussion at the ad-hoc meeting about testing the
readability of RelaxNG by having a "contest" to develop a model for a
portion the Diffserv management model. Are you going to asnnounce this
"contest" to the netconf WG mailing list? I forget just what portion
of Diffserv was chosen for the work.

Will any minutes be published about what transpired at the ad-hoc
meeting?

dbh

> -----Original Message-----
> From: [email-masked] 
> [mailto:[email-masked]] On Behalf Of Simon Leinen
> Sent: Tuesday, November 07, 2006 8:21 PM
> To: [email-masked]
> Subject: RelaxNG examples
>

---

From: Simon Leinen <[email-masked]>
Date: Thu, 16 Nov 2006 15:16:17 +0100

David B Harrington writes:
> readability of RelaxNG by having a "contest" to develop a model for
> a portion the Diffserv management model. Are you going to asnnounce
> this "contest" to the netconf WG mailing list?

Yes and no... actually I was thinking that the new NGO mailing list
("Netconf Goes On") would be a better place for that announcement.

What do others think? Are all of you who are interested in data
modeling for NETCONF subscribed to <[email-masked]> yet?

> I forget just what portion of Diffserv was chosen for the work.

The suggestion was "Classifiers", i.e. section 4 of RFC 3290 (An
Informal Management Model for Diffserv Routers).

> Will any minutes be published about what transpired at the ad-hoc

I only took (Jabber) notes from the first part of the meeting - they
are on http://www.ietf.org/meetings/ietf-logs/netconf/2006-11-07.html.
Providing minutes is a challenge that I don't feel up to...
-- 
Simon.