Should Subject Matter Experts Determine XML Data Implementations?

["Costello, Roger L." <costello@mitre.org>]

Hi Folks,

Let me divide the world into two camps:

1. Subject Matter Experts (SMEs): these are people that are experts in
a subject (domain), but are not necessarily expert at the technologies
employed to implement the subject/domain.

2. Technology Experts: these are people that are experts at the
technologies, but are not necessarily expert in the subject matter.

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Consider the following process to developing an XML data
implementation:

Step 1: SMEs are interviewed about the domain's data and its
hierarchical relationships. A "Data Specification" is created which
captures the domain's data and relationships.

Step 2: Technology experts are then handed the Data Specification to
implement. They create an XML Schema implementation.

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Questions about the development of the XML implementation of the Data
Specification:

1. Should the technology experts be constrained to doing a 1:1 mapping
of the Data Specification to the XML Schema?

2. Or, should the technology experts be at liberty to make alterations
where they see fit? Alterations include using different names,
generalizing, and reorganizing.

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Example: an expert on Books (a Book SME) is interviewed. From the
interview, a "Book Data Specification" is generated. It's a detailed,
complete document, containing such things as prose about what a Book is
and the data that characterizes a Book and the relationships among the
data. Here's a table which succinctly summarizes the Book domain's data
and hierarchy:

Book
    Author ..... String
    Title ...... String
    Date ....... Year
    ISBN ....... Sequence of digit, dashes, and 'x'
    Publisher .. String

The Book Data Specification is then handed off to a technology expert
for him to create an XML data implementation; namely, an XML Schema.

In a 1:1 implementation, the schema declares a <Book> element that is
comprised of <Author>, <Date>, <ISBN>, and <Publisher> elements.

  - Effectively, the SMEs are defining the XML data implementation.

In a non-1:1 implementation, the schema diverges from the Book Data
Specification. For example, suppose the technology expert makes these
changes:

  - Instead of using the term "Publisher" he uses the term Pub, and
thus declares a <Pub> element

  - Instead of single term "Author", he declares multiple terms:

       <Person>
           <GivenName>...</GivenName>
           <Surname>...</Surname>
       </Person>

   - Instead of the term "ISBN" he uses the term GUID (Globally Unique
Identifier)

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Should an XML data implementation of a Data Specification be 1:1 with
the Data Specification? In other words, should SMEs effectively define
XML data implementations?

Or, should technology experts be at liberty to diverge from a Data
Specification and thus change things specified by SMEs?

/Roger