Xml schema: how to achieve <!ENTITY x "y">

[Phil Jarvis]

I have an XML Schema with regular expressions.

e.g. <xsdattern value="[a-zA-Z]{1}[a-zA-Z0-9._=+-]*"/>

I have other patterns in the same schema document which share regular
expression substructure, like the string "[a-zA-Z0-9._=+-]"

I'd like to do something like:

<!ENTITY substring_pattern "[a-zA-Z0-9._=+-]">

And revise my xml schema to look like:

<xsdattern value="[a-zA-Z]{1}&substring_pattern;*"/>


I can't figure out how to generate a reusable literal that can be
embedded in attribute values within an XML schema document.

<!ENTITY> isn't valid xml in an XML schema, at least not as far as my
tests have shown in attempting to validate with a schema using such
declarations.


HELP!


Signed,
cut-and-pasting-for-now-but-tired-of-it

 

[Richard Tobin]

I can't figure out how to generate a reusable literal that can be
embedded in attribute values within an XML schema document.

Schemas don't provide an entity-like mechanism: they just do the
validation bit of DTDs. if you want an entity, put a DTD on your
schema and define one in the usual way.

-- Richard

 

[Phil Jarvis]

I suspect that if I do what you suggest, presumably something like

<!DOCTYPE MySchema SYSTEM "MySchema.dtd">

for an XML schema document which otherwise looks like this:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
...

That both attempts to
(a) run it as input for schema validated xml content or
(b) run it as input for xml validation against the dted

would be a disaster. (I'd have to define the whole
XML Schema in the dtd, for starters, and XML Schema validators would
probably STILL choke on the <!DOCTYPE > statement).

DTD's and XML schema don't mix, I suspect, with the schema validation
tools I use. So I must be missing what you had in mind. Could you give
me an example?

(FYI: I'm just using Sun J2SE 1.4.2 tools)

 

[Toni Uusitalo]

see for example http://java.sun.com/dtd/jspxml.xsd
"View source" if you don't see the DOCTYPE etc.

with respect,
Toni Uusitalo

 

[Richard Tobin]

I suspect that if I do what you suggest, presumably something like

<!DOCTYPE MySchema SYSTEM "MySchema.dtd">

for an XML schema document which otherwise looks like this:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
...

That both attempts to
(a) run it as input for schema validated xml content or
(b) run it as input for xml validation against the dted

would be a disaster. (I'd have to define the whole
XML Schema in the dtd, for starters, and XML Schema validators would
probably STILL choke on the <!DOCTYPE > statement).

There's a DTD for schemas at http://www.w3.org/2001/XMLSchema.dtd, but
you don't need to use a complete DTD, just an internal subset with the
entity you want. Of course if you validate it against an incomplete
DTD it will be invalid, but you don't have to DTD-validate just to use
an entity declaration.

XML Schemas are XML documents, so no Schema validator should "choke"
on a DOCTYPE statement. All XML processors are required to process
the internal subset, so if you put your entity declaration there it
should work.

-- Richard

 

[Phil Jarvis]

Lots of good advice in these replies. I'll try it out.

Thanks!

 

[Phil Jarvis]

Just a followup, the answers (provided in replies) to my questions
worked just fine against schema validation tools and such when I tried them.

Thanks for your help.