Re: [Springframework-developer] Include/import directive in XML bean definition files

[Timo V. <sic...@gm...>]

Alef, J=FCrgen,=20

I've done some research. The XInclude spec is quite short (in terms of=20
the W3C), http://www.w3.org/TR/xinclude/ . Digest:

XInclude transforms the infoset, thus happens after parsing. XInclude=20
defines only two elements: include and fallback. Include uses IRIs=20
(Internationalized Resource Identifiers, essentially URIs) to reference=20
resources. It can import those resources as xml or text. In case of xml=20
it can use XPointer to include only portions of the resource.=20

> How does the XInclude stuff retrieve the resources. Will it allow us
> to specify resources in somewhat the same way as we do now
> (classpath:, etcetera) and is it possible to integrate this with the
> resource package we have?

AFAIK, IRIs/URIs can have application specific form. The XInclude spec=20
explicitly says=20

"The specifics of how an infoset is created are intentionally=20
unspecified, to allow for flexibility by implementations and to avoid=20
defining a particular processing model for components of the XML=20
architecture. Particulars of whether DTD or XML schema validation are=20
performed, for example, are not constrained by this specification."

> > Sounds plausible. I'm no XML expert, though: How could we make this
> > work?

We "only" need a simple layer, which processes all XInclude elements of=20
the infoset (the parsed XML). I couldn't find a simple black box=20
solution, only this:

=2D XIncluder, http://xincluder.sourceforge.net/ : Seems to be=20
unmaintained, not feature complete; nevertheless it's the basis for=20
some other projects (XOM, e.g.).

=2D GNU JAXP, http://www.gnu.org/software/classpathx/jaxp/ : "includes a=20
SAX filter that resolves XIncludes, provided no XPointers are used"

=2D Cocoon XInclude transformer,=20
http://cocoon.apache.org/2.1/userdocs/transformers/xinclude-transformer.htm=
l :=20
Seems to be feature complete, but written for use in cocoon

The Cocoon stuff might be worth reviewing.

BTW, using DTDs for validation has a little drawback: DTDs are not=20
namespace aware. Thus an updated Spring DTD for XInclude would force=20
the user to use a fixed prefix (xi, e.g.). The example I posted was=20
"incorrect", since it defined a namespace in the <beans> tag. FYI, the=20
XInclude spec provides DTD templates (and an XML schema) for XInclude=20
usage:

<!ELEMENT xi:include (xi:fallback?)>
<!ATTLIST xi:include
    xmlns:xi        CDATA       #FIXED   =20
"http://www.w3.org/2001/XInclude"
    href            CDATA       #IMPLIED
    parse           (xml|text)  "xml"
    xpointer        CDATA       #IMPLIED
    encoding        CDATA       #IMPLIED
    accept          CDATA       #IMPLIED
    accept-language CDATA       #IMPLIED
>

<!ELEMENT xi:fallback ANY>
<!ATTLIST xi:fallback
    xmlns:xi   CDATA   #FIXED   "http://www.w3.org/2001/XInclude"
>


Regards,

Timo