Who is right and who does the faulty validation (Me, XMLSpy, lxml.etree or xmllint)

Question

I have tried to validate the following XML with the afterwards following xsd file in the same folder. According to Altova XMLSpy this is completely valid but to help some collegues without licenses to find out about basic faults I have tried to validate the files with python and 'lxml.etree' and also with xmllint. These two say the xml is invalid with the same message:

machineDB.xml:20: Schemas validity error : Element 'canframe': No match found for key-sequence ['remotebus'] of keyref 'busRef'. machineDB.xml fails to validate

Could someone help to find anyones fault?

Versions:

Altova XMLSpy Professional Edition version 2016 rel. 2 sp1 (x64)

lxml.etree versions

Python : sys.version_info(major=2, minor=7, micro=11, releaselevel='final', serial=0) lxml.etree : (3, 7, 2, 0) libxml used : (2, 9, 4) libxml compiled : (2, 9, 4) libxslt used : (1, 1, 29) libxslt compiled : (1, 1, 29)

xmllint (using libxml version 20708)

machineDB.xml file:

<machinedb xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="machinedb.xsd">
    <busdefinition>
        <bus name="displaybus"></bus>
        <bus name="remotebus"></bus>
    </busdefinition>
    <cdefinition>
        <c>
            <canbus bus_ref="remotebus"></canbus>
            <canbus bus_ref="displaybus"></canbus>
        </c>
        <c>
            <canbus bus_ref="displaybus"></canbus>
        </c>
        <c>
            <canbus bus_ref="remotebus"></canbus>
        </c>
    </cdefinition>
    <sdefinition>
        <s>
            <canframe bus_ref="remotebus"></canframe>
        </s>
    </sdefinition>
</machinedb>

machinedb.xsd file:

<xs:schema xmlns:altova="http://www.altova.com/xml-schema-extensions" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning" elementFormDefault="qualified" attributeFormDefault="unqualified" vc:minVersion="1.1">
    <xs:element name="machinedb">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="busdefinition" minOccurs="0">
                    <xs:complexType>
                        <xs:sequence>
                            <xs:element name="bus" minOccurs="0" maxOccurs="unbounded">
                                <xs:complexType>
                                    <xs:attribute name="name" type="NameType" use="required"/>
                                </xs:complexType>
                            </xs:element>
                        </xs:sequence>
                    </xs:complexType>
                </xs:element>
                <xs:element name="cdefinition" minOccurs="0">
                    <xs:complexType>
                        <xs:sequence>
                            <xs:element name="c" minOccurs="0" maxOccurs="unbounded">
                                <xs:complexType>
                                    <xs:sequence minOccurs="0" maxOccurs="unbounded">
                                        <xs:choice>
                                            <xs:element name="canbus" minOccurs="0" maxOccurs="unbounded">
                                                <xs:complexType>
                                                    <xs:attribute name="bus_ref" type="NameType" use="required"/>
                                                </xs:complexType>
                                            </xs:element>
                                        </xs:choice>
                                    </xs:sequence>
                                </xs:complexType>
                            </xs:element>
                        </xs:sequence>
                    </xs:complexType>
                </xs:element>
                <xs:element name="sdefinition" minOccurs="0">
                    <xs:complexType>
                        <xs:sequence>
                            <xs:element name="s" minOccurs="0" maxOccurs="unbounded">
                                <xs:complexType>
                                    <xs:sequence minOccurs="0" maxOccurs="unbounded">
                                        <xs:choice>
                                            <xs:element name="canframe" minOccurs="0" maxOccurs="unbounded">
                                                <xs:complexType>
                                                    <xs:attribute name="bus_ref" use="required"/>
                                                </xs:complexType>
                                            </xs:element>
                                        </xs:choice>
                                    </xs:sequence>
                                </xs:complexType>
                            </xs:element>
                        </xs:sequence>
                    </xs:complexType>
                </xs:element>
            </xs:sequence>
        </xs:complexType>
        <xs:key name="busKey">
            <xs:selector xpath="busdefinition/bus"/>
            <xs:field xpath="@name"/>
        </xs:key>
        <xs:keyref name="busRef" refer="busKey">
            <xs:selector xpath="cdefinition/c/canbus |sdefinition/s/canframe"/>
            <xs:field xpath="@bus_ref"/>
        </xs:keyref>
    </xs:element>
    <xs:simpleType name="NameType">
        <xs:restriction base="xs:string">
            <xs:pattern value="[\w_]+"/>
        </xs:restriction>
    </xs:simpleType>
</xs:schema>

score 3 · Accepted Answer · edited May 23 '17 at 12:25

3

Interesting question. The problem goes away if you set the type of bus_ref and canbus to xs:string without a custom restriction (see this question):

<xs:attribute name="bus_ref" type="xs:string" use="required"/>
<!--...-->
<xs:attribute name="bus_ref" use="required" type="xs:string"/>

I think (wild conjecture) that this is a specific shortcoming of tools that use libxml and that Xerces and Saxon are behaving correctly.

edited May 23 '17 at 12:25

Community

1
1

answered Jan 26 '17 at 14:12

Mathias Müller

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Thank you very much, I just didn't see the difference. For me in particular I use type="NameType" because of more limitations, but still it is a strange behaviour. – S. Roder Jan 27 '17 at 08:54

score 1 · Answer 2 · answered Jan 26 '17 at 14:50

The schema contains the attribute

vc:minVersion="1.1"

Which indicates that it is an XSD 1.1 schema. Validating it with Liquid XML I get the following results

Using .Net Validating reader it reports that it is valid. The .Net parser is an XSD 1.0 parser and is not aware of the vc:minVersion attributes so just ignores it, treating it as a 1.0 schema.

Using .Xerces Validating in XSD 1.0 mode it fails to validate. Xerces is aware of the vc:minVersion attribute and so ignores the schema as its not in 1.1 mode.

Using .Xerces Validating in XSD 1.1 mode it validates. Xerces is aware of the vc:minVersion and can validate using the XSD 1.1 standard and considers everything to be OK.

Other parsers that don't support XSD 1.1 could go either way.

Incidently, I don't think the schema contains anything that is 1.1 specific (syntactically or functionally), so I'm not sure why its been marked as a 1.1 schema.

But back to your error you are getting, I think this is a quirk of the parser you are using.

Since nothing in the schema is XSD 1.1, why do you think the version info has anything to do with the error the OP is getting? Thanks! — Mathias Müller, Jan 26 '17 at 15:33
Technically the validator should not even see the schema if its not 1.1 compliant (as soon as it sees the attribute vc:minVersion="1.1" it should ignore the rest of the element). I've basically provided the results from some of the main parsers, how any of the other parsers deal with the MinVersion tag is unknown. As a said at the end I think the issue is with the parser you tried not the schema/xml combo. But its possible you will see problems using this schema on other 1.0 parsers. — Sprotty, Jan 26 '17 at 16:00

Who is right and who does the faulty validation (Me, XMLSpy, lxml.etree or xmllint)

2 Answers2