Re: [xsl] XSLT 2.0: Schema-aware processor: What are the compelling advantages over a non-SA processor?

[Abel Braaksma <abel.online@xxxxxxxxx>]

Justin Johansson wrote:
> Hello again,
>
> Per my previous post, I've made a significant personal investment in
> learning XSLT 2.0.  I use Michael Kay's Saxon 8b (non-SA) processor and
> think it absolutely rocks.
>
> To continue on my journey of XSLT enlightenment, I'd like to know what the
> compelling reasons are to use an XSLT 2.0 schema-aware processor.  Is Dr.
> Kay's/Saxonica'a the only one out there?
>   

Do you have a background in general programming? Remember the time that 
GOTO was declared dead and procedural programming came along? Remember 
when around 1993 (smalltalk addicts will give an earlier date I am sure) 
the discussion about OO really hit the market? Remember the quite 
current discussions about the mess that is made by people (often 
self-taught non-programmers trying to program) using untyped languages 
such as Perl, PHP and VB?

It is like many of those discussions: a more structured language will 
help a poor programmer, whereas a less structured language will work 
against him/her. A good programmer can still make a rather good program 
with a poor or weakly typed language, but this same good programmer will 
know how to benefit from the added features that a strongly typed 
language brings.

In terms of XSLT: when you use the Schema aware version, it is closely 
(?) equivalent to a typed language. A typed language will give you 
compile time errors when you use incompatible variables or data without 
the proper handling. The same is true for XSLT. In addition, you can 
validate both input and output (and any other complex type you use 
during processing) right from your xslt processor.

However, note that with non schema aware processors, you can still use 
the the basic schema types, as in:

<xsl:template match="field" as="xs:string*">
   <xsl:sequence select="tokenize(., ',')" />
</xsl:template>

> Probably I'll purchase a copy anyway, even if for no other reason other
> than to show my appreciation for his excellent work and kind open sourcing
> of Saxon non-SA.  Unfortunately the last few XSLT contracts I've had have
> been on MSXML/XSLT 1.0 shops so I haven't had the benefit of employer
> support for XSLT 2.0 let alone a schema-aware processor.

Most of the time, a project the uses XSLT 1.0 can easily be upgraded to 
XSLT 2.0. You can tell your employers that all it takes is a .NET 
library in their projects. Perhaps they already use .NET in which case 
it is even easier. Sticking to XSLT 1.0 in any given project, unless 
locked in by a vendor, is ludicrous, I think.


Cheers,
-- Abel Braaksma