XML Editor
Sign up for a WebBoard account Sign Up Keyword Search Search More Options... Options
Chat Rooms Chat Help Help News News Log in to WebBoard Log in Not Logged in
Show tree view Topic
Topic Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Go to previous topicPrev TopicGo to next topicNext Topic
Postnext
Jeff CannizzoSubject: XML Mapping to SGML DTD
Author: Jeff Cannizzo
Date: 13 Sep 2002 07:46 PM
I am trying to map an XML DTD to an SGML DTD. Which is the 87269 DTD. The problem that I am having is, when selecting the 87269 DTD as the destination schema, no root elements are included. Is there any way to fix this?


Document87269.zip

Postnext
Alberto MassariSubject: Re: XML Mapping to SGML DTD
Author: Alberto Massari
Date: 14 Sep 2002 12:04 AM
Hi Jeff,
the file 87269.dtd is not a valid DTD according to the XML specs, and
Stylus Studio only supports DTDs as defined in
http://www.w3.org/TR/REC-xml. The file can be a valid DTD according to the
SGML specs, but XML has been defined as a subset of the SGML grammar,
removing features that made SGML quite unpractical to be handled/validated.

Looking at this file in particular, SGML allows the definition for an
external parameter entities like

<!ENTITY % dietmdb-a PUBLIC "-//USA-DOD//DTD Content Data Model Generic
Layer//EN" >

while the XML specs always require a "system id" to be specified, like in

<!ENTITY % dietmdb-a PUBLIC "-//USA-DOD//DTD Content Data Model Generic
Layer//EN" "dietmdb-a.ent">

****
the relevant BNF from the XML schema spec is
[70] EntityDecl ::= GEDecl | PEDecl
[72] PEDecl ::= '<!ENTITY' S '%' S Name S PEDef S? '>'
[74] PEDef ::= EntityValue | ExternalID
[75] ExternalID ::= 'SYSTEM' S SystemLiteral | 'PUBLIC' S PubidLiteral S
SystemLiteral
****

Also, you use a "- O" inside the definition of elements, but this is not
allowed inside an XML DTD.

****
[45] elementdecl ::= '<!ELEMENT' S Name S contentspec S? '>' [VC:
Unique Element Type Declaration]
[46] contentspec ::= 'EMPTY' | 'ANY' | Mixed | children
[47] children ::= (choice | seq) ('?' | '*' | '+')?
[48] cp ::= (Name | choice | seq) ('?' | '*' | '+')?
[49] choice ::= '(' S? cp ( S? '|' S? cp )+ S? ')'
[50] seq ::= '(' S? cp ( S? ',' S? cp )* S? ')'
[51] Mixed ::= '(' S? '#PCDATA' (S? '|' S? Name)* S? ')*' | '(' S?
'#PCDATA' S? ')'
****

Hope this helps,
Alberto

Postnext
Jeff CannizzoSubject: Re: XML Mapping to SGML DTD
Author: Jeff Cannizzo
Date: 21 Sep 2002 05:51 PM
So can I change these things in the DTD to make it work? Any help would be great!.

Thanks

Postnext
Alberto MassariSubject: Re: XML Mapping to SGML DTD
Author: Alberto Massari
Date: 23 Sep 2002 06:30 AM
Try the attached modified files; however, keep in mind that this DTD should only be used as an input for Mapper and not to validate XML files, as it's not equivalent to the one you posted.
This because the DTD syntax, as defined by the XML spec, does not have the same expressive power of the one defined by the SGML spec, so this version enforces less constraints on the data.

Hope this helps,
Alberto

Postnext
Alberto MassariSubject: Re: XML Mapping to SGML DTD
Author: Alberto Massari
Date: 23 Sep 2002 06:32 AM
Here is the attachment.

Alberto


Documentsgml.zip
Modified DTD files

Postnext
Jeff CannizzoSubject: Re: XML Mapping to SGML DTD
Author: Jeff Cannizzo
Date: 23 Sep 2002 08:49 PM
Thank you for the help! I would like to do this to other SGML DTD's for conversion that I am doing. Is there any guidance you can give me on what exactly you did?

Posttop
Alberto MassariSubject: Re: XML Mapping to SGML DTD
Author: Alberto Massari
Date: 24 Sep 2002 04:16 AM
Hi Jeff,
here is a list of the conversions I did; please note that the DTD obtained
by running these steps is not strictly equivalent to the source SGML. The
XML specs have greatly reduced the expressivity of DTDs with the aim of
making them less complex, so the result DTD would validate data files that
the original DTD would reject as invalid.

1) definition of external parameter entities in SGML doesn't have the
"system ID". So, you need to add the location of the file to be included

ENTITY % dietmdb-a PUBLIC "-//USA-DOD//DTD Content Data Model Generic
Layer//EN"

must become

ENTITY % dietmdb-a PUBLIC "-//USA-DOD//DTD Content Data Model Generic
Layer//EN" "ietmdba"

2) element definition has a couple of character chosen between "-", "O" and
"o" between the name and the children model, that you need to remove.
For example,

ELEMENT techinfo - - ( version+, (%system;)+ )

must become

ELEMENT techinfo ( version+, (%system;)+ )

3) SGML allows to put comments inside the definitions of entities and
element, between "--" markers, that you need to remove.
For example,

ENTITY alpha "[alpha ]" --Greek letter lowercase alpha --

must become

ENTITY alpha "[alpha ]"

4) in SGML you can define multiple elements in the same declaration, like in

ELEMENT (sup | sub) (%f.text; | %f.oper;)+

You need to create one ELEMENT definition for each element

ELEMENT sup (%f.text; | %f.oper;)+
ELEMENT sub (%f.text; | %f.oper;)+

5) DTD introduced the restriction that, when an element has #PCDATA nodes
as children, the definition for this element must be in the form (#PCDATA |
child1 | child2 ....)*
So, every time the SGML definition involves a #PCDATA element, you need to
rearrange it so that it has this form. BTW, this new form is less
restrictive, like in this example

ENTITY % f.text "#PCDATA | roman | italic | ov"
ENTITY % f.oper "mark | markref | break | sup | sub | sum | integral |
product | plex | frac | diff | sqrt | root | square | power | pile |
matrix | fence | middle | tensor | mfn | box | vec"

ELEMENT mfn ((fname , of) | (%f.text; | %f.oper;)+)>

that must be changed into

ELEMENT mfn (%f.text; | fname | of | %f.oper;)*>

6) SGML has more attribute types, e.g. NUTOKEN, NUTOKENS, NAME, NAMES; the
first two should be mapped to NMTOKEN and NMTOKENS, the last ones should be
changed into plain CDATA. It also has a modifier, #CONREF, that should be
changed into #IMPLIED. Also, the default value for enumerated values should
be placed between quotes.

Hope this helps,
Alberto

 
Topic Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Go to previous topicPrev TopicGo to next topicNext Topic
Download A Free Trial of Stylus Studio 6 XML Professional Edition Today! Powered by Stylus Studio, the world's leading XML IDE for XML, XSLT, XQuery, XML Schema, DTD, XPath, WSDL, XHTML, SQL/XML, and XML Mapping!  
go

Log In Options

Site Map | Privacy Policy | Terms of Use | Trademarks
Stylus Scoop XML Newsletter:
W3C Member
Stylus Studio® and DataDirect XQuery ™are from DataDirect Technologies, is a registered trademark of Progress Software Corporation, in the U.S. and other countries. © 2004-2016 All Rights Reserved.