xml:id RE: [sc34wg3] Compact syntax requirement question

Lars Marius Garshol sc34wg3@isotopicmaps.org
Tue, 19 Jul 2005 17:56:06 +0200

* Lars Marius Garshol
| However, the use case that clinched this for us at the meeting, and
| which every person who has contributed to this thread has ignored so
| far is that we need CTM for TMQL. And TMQL is not going to have an
| XML syntax, which means that whoever is writing TMQL will already be
| writing a plain text syntax.

* Patrick Durusau
| Not so much ignored as thought to be yet another claim that needs
| further explanation. ;-)

If you wanted an explanation it would have been a lot more efficient
to ask for one straight away. Anyway, see my reply to Bernard.

| [scope statement of 18048]
| I took that to mean (perhaps incorrectly) that TMQL was defining a
| formal language for querying topic maps and not a concrete syntax
| (of which there might be several) for querying topic maps.

It says we're providing "a syntax". What's unclear about that?

| Any concrete syntax and its processor would have to follow the
| strictures defined by the formal language defined by TMQL.

Well, the whole point of making TMQL a standard is that there will be
only a single syntax, so that you can take your query from
implementation A to implementation B without changing it. If A and B
use different syntaxes (like we had with HyTM) then you can't do that,
and you might as well not have a standard in the first place.
| In further support of that reading, which I admit may be incorrect, I
| note that 3.1 Notation and Syntax says:
| > The syntax of TMQL is defined using the EBNF formalism defined in
| > [XML 1.0].
| So TMQL is being defined using EBNF, which I didn't take to mean a
| standard syntax in the sense that most users understand the term.

Why not? Why would we write "the syntax" and mean something other than
how the term is usually understood?
| BTW, I am curious why the reference here is not to the standard EBNF
| formalism rather than that of XML. I have not checked but is there a
| difference? EBNF was not defined by XML 1.0 as I recall. ;-)

We decided on the XML 1.0 EBNF because it's the most readable version
that's widely used out there. ISO has one, but, well, I don't like it,
and the IETF also has one, but I really don't like that, either.
Further, the XML 1.0 EBNF is used in almost all W3C specs that use
BNF, so it's pretty widely known.
| Sure, one could write queries using the EBNF as specified in TMQL,
| but I am not sure that assumption is a transparent as some may have
| thought.

Patrick, it really is difficult to see what other way it could have
been understood. I'm sorry, but what EBNF is usually used for is to
define concrete syntax. The one exception I'm aware of is SGML, and
that really is an anomaly that took a lot of flak for being an
| It would also be possible to write an equivalent query language that
| following the rules as specified without being limited to the
| spareness of the EBNF grammar as given.

Yes, it's possible for someone to define another syntax for that maps
to the same underlying query structures, but we didn't write that we
were going to have any kind of machinery of this type, and so it seems
a fair assumption that we weren't going to create one without telling
| BTW, compact syntax fans, don't take these questions as being
| unsympathetic to a compact syntax or even one in plain text. I don't
| think one size fits all in almost all circumstances and the better
| we identify the concerns of the communities to be served, the faster
| the adoption will be of the solutions we offer them.

Okay, but that makes me wonder why we are having this discussion at
all. What's the point?

Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >