Re: [xml] New user, evaluating XML libraries

[Boris Kolpackov <boris codesynthesis com>]

Hi Daniel,


Daniel Veillard <veillard redhat com> writes:

>   Le'ts be frank, it's a bit of FUD, Schemas is being implemented, it's
> not fully implemented because the spec is basically broken beyond recovery.

I thought it is because Kasimier is missing in action ;-). But, I agree,
XML Schema is not the easiest spec to read.


> ... SAX not formerly defined except for Java. On the other hand the
> XMLTextReader from C# is part of the ECMA C# spec, and is a good API.

You mean SAX, which is only defined for Java, is a bad thing but
XMLTextReader, which is only define for C#, is good? ;-)


>   Also DOM *requires* UTF-16 for all strings. This means that in general
> 1/ you will loose time, most content around is UTF-8
> 2/ you will loose memory space/cache efficiency as the converted output is
>    way larger in average
> 3/ you will looose CPU efficiency as breaking cache is #1 performance
>    problem in modern computers

I think it largely depends on what kind of data one is handling. If there
are a lot of non-latin characters then UTF-8 will waste at leaset as much
and normally a lot more (4-byte surrogate pairs) space than UTF-16.


>   There is no functional XSD validator. Go to the xmlschemas-dev
> archive at W3C, check the last 5 questions from Michael Kay (who is
> a Schemas implementor and one of the W3C spec writers), they are unanswered
> for weeks now, nobody can tell what it is supposed to do. Trying to use
> XSD to promote interoperability or validation of data is kind of a joke.
> Relax-NG on the other hand is an ISO standard, has a formal specification
> and can be read and understood by most programmers in a matter of a couple
> of days.

While what you say could be true, most XML parsers these days support
XML Schema while there is hardly any that support Relax-NG. Also there
are a lot of industry standards organizations that managed to define
interoperable schemas that describe fairly complex XML vocabularies.
Finally, one last thing, that a lot of people tend to overlook, is that
it is fairly straightforward (in most cases) to provide XML data
binding (generated types in a programming language that represent the
given vocabulary) from XML Schema. I do not think it will be anywhere
as easy or at all possible to do the same with Relax-NG.


hth,
-boris


-- 
Boris Kolpackov
Code Synthesis Tools CC
http://www.codesynthesis.com
Open-Source, Cross-Platform C++ XML Data Binding