Ing. Tarin Gamberini

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Home > Java > How to validate DocBook 5.0 in Netbeans 7.0.1

How to validate DocBook 5.0 in Netbeans 7.0.1

Created Monday 19 September 2011

Table of Contents

• The problem
• Setting up a DocBook 5.0 local copy
• Investigating
• Tarin's Workaround

The problem

This is the DocBook sample_article.xml I'd like validating:

<?xml version='1.0' encoding='UTF-8'?>
<article version="5.0" xml:lang="en"
  xmlns="http://docbook.org/ns/docbook"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xsi:schemaLocation="
    http://docbook.org/ns/docbook 
      http://docbook.org/xml/5.0/xsd/docbook.xsd">
    <title>Sample article</title>
    <para>This is a very short article.</para>
</article>

I've tried validating sample_article.xml In NetBeans:

unfortunately NetBeans logs:

XML validation started.
Checking file:/C:/sample_article.xml...
Referenced entity at "http://docbook.org/xml/5.0/xsd/docbook.xsd".
Referenced entity at "http://docbook.org/xml/5.0/xsd/xlink.xsd".
Referenced entity at "nbres:/org/netbeans/modules/j2ee/ddloaders/catalog/resources/XMLSchema.dtd".
Referenced entity at "nbres:/org/netbeans/modules/j2ee/ddloaders/catalog/resources/datatypes.dtd".
src-resolve: Cannot resolve the name 'xml:id' to a(n) 'attribute declaration' component. [6] http://docbook.org/xml/5.0/xsd/docbook.xsd
s4s-elt-must-match.1: The content of 'db.common.attributes' must match (annotation?, ((attribute | attributeGroup)*, anyAttribute?)). A problem was found starting at: attribute. [6] http://docbook.org/xml/5.0/xsd/docbook.xsd
cvc-complex-type.3.2.2: Attribute 'version' is not allowed to appear in element 'article'. [6] 
cvc-complex-type.3.2.2: Attribute 'xml:lang' is not allowed to appear in element 'article'. [6] 
XML validation finished.

But wait a moment! Where does NetBeans get docbook.xsd? If I disconnect my PC from Internet, and I retry validating the sample_article.xml again, NetBeans logs:

XML validation started.
Checking file:/C:/sample_article.xml...
Referenced entity at "http://docbook.org/xml/5.0/xsd/docbook.xsd".
schema_reference.4: Failed to read schema document 'http://docbook.org/xml/5.0/xsd/docbook.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>. [6]
cvc-elt.1: Cannot find the declaration of element 'article'. [6]
Referenced entity at "http://docbook.org/xml/5.0/xsd/docbook.xsd".
schema_reference.4: Failed to read schema document 'http://docbook.org/xml/5.0/xsd/docbook.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>. [7]
Referenced entity at "http://docbook.org/xml/5.0/xsd/docbook.xsd".
schema_reference.4: Failed to read schema document 'http://docbook.org/xml/5.0/xsd/docbook.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>. [8]
XML validation finished.

Clearly NetBeans validates sample_article.xml against the http://docbook.org/xml/5.0/xsd/docbook.xsd file on Internet, but something goes wrong. So I've decided to investigate using a DocBook 5.0 local copy.

Setting up a DocBook 5.0 local copy

I've downloaded the docbook-5.0.zip from the DocBook 5.0 distribution page , and I've expanded it in a NetBeans project. Than I've disconnected my PC from Internet and I've said to NetBeans where I've expanded the docbook.xsd file by the Tools > DTDs and XML Schemas menu:

Then I've added a local schema under the User Catalog: binding the http://docbook.org/xml/5.0/xsd/docbook.xsd URI location to the actual docbook.xsd file location by the System ID button:

Trying re-validating the sample_article.xml NetBeans logs the previously seen error:

XML validation started.
Checking file:/C:/sample_article.xml...
Referenced entity at "http://docbook.org/xml/5.0/xsd/docbook.xsd".
Referenced entity at "http://docbook.org/xml/5.0/xsd/xlink.xsd".
Referenced entity at "nbres:/org/netbeans/modules/j2ee/ddloaders/catalog/resources/XMLSchema.dtd".
Referenced entity at "nbres:/org/netbeans/modules/j2ee/ddloaders/catalog/resources/datatypes.dtd".
src-resolve: Cannot resolve the name 'xml:id' to a(n) 'attribute declaration' component. [6] http://docbook.org/xml/5.0/xsd/docbook.xsd
s4s-elt-must-match.1: The content of 'db.common.attributes' must match (annotation?, ((attribute | attributeGroup)*, anyAttribute?)). A problem was found starting at: attribute. [6] http://docbook.org/xml/5.0/xsd/docbook.xsd
cvc-complex-type.3.2.2: Attribute 'version' is not allowed to appear in element 'article'. [6] 
cvc-complex-type.3.2.2: Attribute 'xml:lang' is not allowed to appear in element 'article'. [6] 
XML validation finished.

Finally I've set up a DocBook 5.0 local copy and I've recreated the on-line error, so I'm ready to investigate.

Investigating

In the docbook-5.0\xsd\ directory there's the docbook.xsd. At line 6 there's: <xs:attribute ref="xml:id"/>

It seams NetBeans isn't able to locate the xml.xsd in the docbook-5.0\xsd\ directory even if docbook.xsd declares at line 4:

<xs:import 
  namespace="http://www.w3.org/XML/1998/namespace" 
  schemaLocation="xml.xsd"/>

By the way... I've bound the xml.xsd URI location to the actual xml.xsd file location as I've still done before: so I've ended up with the two cataloged xsd: the docbook.xsd and the xml.xsd.

Trying re-validating the sample_article.xml NetBeans logs the previously seen error again:

XML validation started.
Checking file:/C:/sample_article.xml...
Referenced entity at "http://docbook.org/xml/5.0/xsd/docbook.xsd".
Referenced entity at "http://docbook.org/xml/5.0/xsd/xlink.xsd".
Referenced entity at "nbres:/org/netbeans/modules/j2ee/ddloaders/catalog/resources/XMLSchema.dtd".
Referenced entity at "nbres:/org/netbeans/modules/j2ee/ddloaders/catalog/resources/datatypes.dtd".
src-resolve: Cannot resolve the name 'xml:id' to a(n) 'attribute declaration' component. [6] http://docbook.org/xml/5.0/xsd/docbook.xsd
s4s-elt-must-match.1: The content of 'db.common.attributes' must match (annotation?, ((attribute | attributeGroup)*, anyAttribute?)). A problem was found starting at: attribute. [6] http://docbook.org/xml/5.0/xsd/docbook.xsd
cvc-complex-type.3.2.2: Attribute 'version' is not allowed to appear in element 'article'. [6] 
cvc-complex-type.3.2.2: Attribute 'xml:lang' is not allowed to appear in element 'article'. [6] 
XML validation finished.

I've tried several URI combined with various User Catalog and Catalog Resolver but, in my opinion, there's something wrong in how NetBeans binds URI location to actual file location. I suppose NetBeans tries getting the file only if its URI has the form of an URL, downloading the file from Internet, while if the file hasn't the URL form NetBeans doesn't try interpreting the URL as a relative pathname to an actual file.

I've found a solved bug but I'm not sure that is completely solved, as someone else has commented.

Tarin's Workaround

This is the workaround I've came up to get DocBook 5.0 validation working in Netbeans 7.0.1. The idea is based on the facts investigated in the Investigating section above: NetBeans succesfully resolves URI only if they are in a URL form.

Before going on, if you've done what I did in the preceding sections, remove docbook.xsd and xml.xsd from User Catalog.

Firstly download the docbook-5.0.zip from the DocBook 5.0 distribution page , and expand it in a NetBeans project (probably you may like a project that builds a docbook-xml-5.0-wrapper.jar).

Then in the docbook-5.0\xsd\docbook.xsd file change URI schema locations from the relative pathname form:

<xs:import 
  namespace="http://www.w3.org/1999/xlink" 
  schemaLocation="xlink.xsd" />
<xs:import 
  namespace="http://www.w3.org/XML/1998/namespace" 
  schemaLocation="xml.xsd" />

to the URL form:

<xs:import 
  namespace="http://www.w3.org/1999/xlink" 
  schemaLocation="http://docbook.org/xml/5.0/xsd/xlink.xsd" />
<xs:import 
  namespace="http://www.w3.org/XML/1998/namespace" 
  schemaLocation="http://docbook.org/xml/5.0/xsd/xml.xsd" />

Now put the systemCatalog.xml I've created in the same directory in which there's the docbook-5.0 folder of the DocBook 5.0 distribution:

Finally add a catalog resolver for the just added systemCatalog.xml:

Trying re-validating the sample_article.xml NetBeans successfully logs:

XML validation started.
Checking file:/C:/sample_article.xml...
XML validation finished.