Re: [xml-dev] Why does XML Schema allow elements with complex type tobe

I don't think you should use nillible for the case of someone who has no middle name. That is simple optionality.

nillible is for a more esoteric purpose: where whether that person has a middle name or not has not been disclosed. This may because you don't know, the client didn't ask, or you dont want to tell.

Think "elision" or "incomplete data". Think partial record transmission, rather than Java or database nulls.

In Australia, we have legal cases that are suppressed by courts. Ordinary suppression you cannot give details of the judgment or sonduct. Total suppression you cannot even mention the case exists.

If you request a suppressed case from some online database, you might get

(or whatever the syntax is) but if you request a totally suppressed case you should get a 400 or 500 error (or whatever they use for a query that srlects nothing.)

Is this a good thing for a schema language to have? ... ...

Rick

On Thu, 11 Jul. 2019, 23:17 Costello, Roger L., <costello@mitre.org> wrote:

Hi Folks,

XML Schema allows elements with simple type to be nillable. For example, for the real world use case of some people not having a middle name, I declare a nillable <MiddleName> element:

<xsd:element name="MiddleName" nillable="true" type="xsd:string" />

Then I can create XML instance documents for people that do not have a middle name:

<Name>

    <FirstName>John</FirstName>

    <MiddleName xsi:nil="true"></MiddleName>

    <LastName>Doe</LastName>

</Name>

Nice!

XML Schema also allows elements with complex type to be nillable. Thus, I could declare the <Name> element to be nillable:

<xsd:element name="Name" nillable="true">

    <xsd:complexType>

        <xsd:sequence>

            <xsd:element name="FirstName" type="xsd:string" />

            <xsd:element name="MiddleName" nillable="true" type="xsd:string" />

            <xsd:element name="LastName" type="xsd:string" />

        </xsd:sequence>

    </xsd:complexType>

</xsd:element>

And then I can create XML instance documents with <Name> elements having a nil value:

<Name xsi:nil="true" />

Why?

Why did the XML Schema working group allow elements with complex type to be nillable?

Did the XML Schema working group examine other real world data formats and discover that some of them allow regions with complex content to be nillable? If yes, what are those other real world data formats that allow regions with complex content to be nillable?

/Roger