Re: [xml-dev] defining correctness for an XML transformation

Hi Folks,

One of the things that I have learned from this discussion is the importance of a good specification. It is difficult to convert one XML element to another XML element if you have a fuzzy understanding of the two elements.

So, I have nailed down the specifications for <Airport_Name> and <name> ….

Initially I thought the specification for <Airport_Name> was simple: a 30-character fixed length string, composed of ASCII characters. Here is the XSD I created for that specification:

<xs:element name="Airport_Name">
    <xs:simpleType>
        <xs:restriction base="xs:string">
            <xs:length value="30"/>
        </xs:restriction>
    </xs:simpleType>
</xs:element>

Then you started asking probing questions: Is Airport_Name required? Can there be leading spaces? Are trailing spaces allowed? Are multiple internal spaces allowed? Are duplicates allowed, i.e., can there be multiple airports with the same name? You said that only ASCII characters are permitted, but your XSD doesn’t reflect that. Can <Airport_Name> be blank, i.e., 30 spaces?

The document/specification I have for Airport_Name doesn’t answer any of those questions, so I examined the data file that I have to get some answers. Here’s what I found:

Is <Airport_Name> required? Yes

Can there be leading spaces in an airport name? No

Can there be trailing spaces? Yes

Are multiple internal spaces allowed? Yes

Are duplicates allowed? Yes

What characters are permitted in an airport name? A-Z, forward slash, left paren, right paren, comma, dash, digits, apostrophe, ampersand, quote, space

Can <Airport_Name> be all blanks? No

Based on those answers, I updated my XSD:

<xs:element name="Airport_Name">
    <xs:simpleType>
        <xs:restriction base="xs:string">
            <xs:length value="30"/>
            <xs:pattern value="[A-Z/\(\),\-0-9'&"][A-Z/\(\),\-0-9'&" ]+"/>
        </xs:restriction>
    </xs:simpleType>
</xs:element>

Recall that I need to convert <Airport_Name> to <name>. Initially my specification of <name> was simple: The value of <name> is a string up to 50 characters, with no trailing spaces. Here is my XSD for the <name> element:

<xs:element name="name">
    <xs:simpleType>
        <xs:restriction base="xs:string">
            <xs:maxLength value="50"/>
        </xs:restriction>
    </xs:simpleType>
</xs:element>

I asked the same questions for the <name> element:

Is <name> required? No

Can there be leading spaces? No

Can there be trailing spaces? No

Are multiple internal spaces allowed? Yes

Are duplicates allowed: Yes

What characters are permitted in an airport name? Use the same set of characters that <Airport_Name> uses

Can <name> be all blanks? No

The yellow means it is different from <Airport_Name>.

Here’s my updated XSD:

<xs:element name="name">
    <xs:simpleType>
        <xs:restriction base="xs:string">
            <xs:maxLength value="50"/>
            <xs:pattern value="[A-Z/\(\),\-0-9'&"][A-Z/\(\),\-0-9'&" ]*[A-Z/\(\),\-0-9'&"]"/>
        </xs:restriction>
    </xs:simpleType>
</xs:element>

Have I missed anything? Are there additional questions that need answering? Are my specifications complete?

/Roger