Re: [xml-dev] [XSD question] Does ref'ing to the same global elementdecl

The alternative, although gaining popularity in software (mainly because of microservices routinely violating DRY) , is to repeat Title even more, by declaring it locally, and each repetition would get its own evolutionary path of attributes, etc. Yes? That would violate DRY even more since these attributes would likely be very similar in semantics but not quite the same in syntax (spelling, datatypes), and code based on this schema would be likely to have to reproduce those DRY violations and need lots of mappings.

On Thu, 6 Jan 2022 at 12:44, Roger L Costello <costello@mitre.org> wrote:

Hi Folks,

Below is an XML Schema for a Bookstore. The Bookstore has any number of Books followed by any number of Magazines. Each Book has a Title and Publisher (and other things). Each Magazine also has a Title and Publisher (and other things). The Book element ref's to a globally declared Title element and ref's to a globally declared Publisher element. Ditto for the Magazine element.

Title is declared once:

<xs:element name="Title" type="xs:string" />

but ref'ed twice (once from Book and once from Magazine):

<xs:element ref="Title" />
<xs:element ref="Title" />

Ditto for Publisher.

Do multiple ref's to the same element constitute a violation of the Don't Repeat Yourself (DRY) principle? /Roger
-----------------------------------------------
<xs:element name="Bookstore">
<xs:complexType>
<xs:sequence>
<xs:element name="Book" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element ref="Title" />
<xs:element ref="Publisher" />
...
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="Magazine" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element ref="Title" />
<xs:element ref="Publisher" />
...
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>

<xs:element name="Title" type="xs:string" />
<xs:element name="Publisher" type="xs:string" />
...

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