LISTSERV mailing list manager LISTSERV 16.0

Help for XML-L Archives


XML-L Archives

XML-L Archives


XML-L@LISTSERV.HEANET.IE


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

XML-L Home

XML-L Home

XML-L  May 2000

XML-L May 2000

Subject:

Re: XML and inheritence (reuse DTDs)

From:

Daryl Luk <[log in to unmask]>

Reply-To:

General discussion of Extensible Markup Language <[log in to unmask]>

Date:

Thu, 4 May 2000 15:07:08 +0100

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (115 lines)

Hi Ron,

Your response to the reuse of dtd is very helpful.  But I
am still struggling with multi-level of DTDs reuse.  A simple
example is like that:

I have 4 DTDs and 1 xml file:
a.dtd - uses c.dtd (via parameter entity)
b.dtd - uses c.dtd also (via parameter entity)
c.dtd - standalone
d.dtd - uses a.dtd and b.dtd (as a result, reference
        c.dtd indirectly twice)

--------- a.dtd -------------
<?xml version="1.0" encoding="UTF-8"?>
<!ENTITY % c SYSTEM "c.dtd">
%c;
<!ELEMENT a (c*)>
--------- b.dtd -------------
<?xml version="1.0" encoding="UTF-8"?>
<!ENTITY % c SYSTEM "c.dtd">
%c;
<!ELEMENT b (c*)>
--------- c.dtd -------------
<?xml version="1.0" encoding="UTF-8"?>
<!ELEMENT c EMPTY>
--------- d.dtd -------------
<?xml version="1.0" encoding="UTF-8"?>
<!ENTITY % a SYSTEM "a.dtd">
%a;
<!ENTITY % b SYSTEM "b.dtd">
%b;
<!ELEMENT d (a*,b*)>
--------- d.xml -------------
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE d SYSTEM "d.dtd">
<d><a></a></d>

XML4J 2.0.15 and XML Spy 3.0 both correctly complain
duplicated element "c".  Do you know how to reuse a.dtd
and b.dtd in this case?  I don't think I want to remove
c element from a.dtd or b.dtd because people may use a.dtd
(or b.dtd) in some cases while others may use d.dtd in other
cases.

Does XML schema suppose to fix this kind of design? or I
have to look somewhere eles?

(Please see if you can cc your response to [log in to unmask] as
well, thanks)


Daryl Luk

On Thu, 23 Sep 1999 11:10:28 +0200, Ronald Bourret
<[log in to unmask]> wrote:

>Steven Williams wrote:
>
>> I was wondering if XML has the ability to incorporate one DTD into
>another? This
>> is a purely theoretical question so I do not have a concrete example to
>clarify
>> my question, but say, for instance, I have a DTD for a generic order and
>now
>> want to create a DTD for a book order that uses everything in the generic
>order
>> plus extra elements/attributes. Can I do this easily? Am I trying to do
>> something that shouldn't be done?
>
>Reusing one DTD in another is fairly easy -- you simply cut and paste or
>use an external entity. For example, suppose my order DTD is in a file
>called order.dtd and that the root element is Order. In my book order DTD I
>might do something like:
>
>   <!ELEMENT BookOrder (Title, Order)>
>   <!ELEMENT Title (#PCDATA)>
>   <!ENTITY % orderdtd SYSTEM "order.dtd">
>   %orderdtd;
>
>The ENTITY statement declares the order DTD as an external parameter entity
>and the %orderdtd; statement inserts it into the current DTD. Note that I
>needed to combine my DTD to the order DTD -- that is, I referred to the
>Order element in the order DTD in my BookOrder element. All that the
>external entity mechanism does is insert something -- you still have to
>pick up the pieces yourself.
>
>A second possibility -- if you only want to add attributes to the order DTD
>-- is to declare those attributes in the internal subset and refer to the
>order DTD as the external subset. This is possible because multiple ATTLIST
>statements are legal for a single element type. For example, if I wanted to
>reuse the order DTD but add a Title attribute to the Order element, I could
>do this as follows:
>
>   <!DOCTYPE Order SYSTEM "order.dtd" [
>      <!ATTLIST Order
>                Title CDATA #REQUIRED>
>   ]>
>
>But if what you really want is inheritance in the object-oriented sense --
>that is, to reuse the Order element but rename it as, say, BookOrder and
>change it's content model a bit -- you'll have to wait a bit. This can't be
>done in DTDs, but there are a number of proposals for how to do it in XML
>schema languages. For example, take a look at the Archetype element in the
>W3C's Schema Language or similar elements in SOX. The problem with all of
>this is that most XML software doesn't support schemas yet, so you probably
>won't be able to use it. (An exception might be XML Authority from
>Extensibility -- see http://www.extensibility.com).
>
>For more info:
>
>W3C Schemas: http://www.w3.org/TR/xmlschema-1/
>SOX: http://www.w3.org/TR/NOTE-SOX/
>
>-- Ron Bourret

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

March 2016
January 2016
July 2014
April 2014
January 2014
July 2013
February 2013
September 2012
August 2012
October 2011
August 2011
June 2011
January 2011
November 2010
October 2010
July 2010
June 2010
March 2010
February 2010
January 2010
November 2009
September 2009
August 2009
July 2009
May 2009
March 2009
December 2008
October 2008
August 2008
May 2008
March 2008
February 2008
January 2008
December 2007
October 2007
August 2007
June 2007
March 2007
January 2007
December 2006
September 2006
July 2006
June 2006
April 2006
February 2006
January 2006
November 2005
September 2005
August 2005
July 2005
June 2005
May 2005
March 2005
January 2005
October 2004
August 2004
July 2004
June 2004
May 2004
March 2004
February 2004
January 2004
December 2003
November 2003
October 2003
September 2003
August 2003
July 2003
June 2003
May 2003
April 2003
March 2003
February 2003
January 2003
December 2002
November 2002
October 2002
September 2002
August 2002
July 2002
June 2002
May 2002
April 2002
March 2002
February 2002
January 2002
December 2001
November 2001
October 2001
September 2001
August 2001
July 2001
June 2001
May 2001
April 2001
March 2001
February 2001
January 2001
December 2000
November 2000
October 2000
September 2000
August 2000
July 2000
June 2000
May 2000
April 2000
March 2000
February 2000
January 2000
December 1999
November 1999
October 1999
September 1999
August 1999
July 1999
June 1999
May 1999
April 1999
March 1999
February 1999
January 1999
December 1998
November 1998
October 1998
September 1998
August 1998
July 1998
June 1998
May 1998
April 1998
March 1998
February 1998
December 1997
November 1997
October 1997

ATOM RSS1 RSS2



LISTSERV.HEANET.IE

CataList Email List Search Powered by the LISTSERV Email List Manager