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.