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Metamodel Notes from 2020-08-25.md

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From [[Metamodel 2020-08-25 08_28]]:

What problems does it solve?

  • Multiple rendering targets
    • Easier support for multiple dev environments
  • Eliminates needing to reverse engineer NIEM concepts from Schema
    • There's a concept => schema mapping that isn't trivially reversible
    • Makes tools easier
    • Improved understanding via the distribution
  • Eliminates conversions between render targets
    • Not for instances, though
  • Abstract terms instead of the concrete schema representation
  • Place to put aspects that may not appear in a render target
    • XML vs JSON difference, things like cardinality, element order, parent types, XML schema data types
  • Doesn't force people to use XML Schema when their endgame is JSON
  • Component names
    • How should we model names well?
    • We have the pieces, object, representation, qualifiers etc.
    • each may be multiple terms
    • We pack them into long concatenations, which loses all the info
    • Which words are with which terms, and which are modifiers?
    • Allows for different naming schemes for different render targets, plus
      • Java code
      • Documentation, diagrams
    • This could be a later stage
  • Can do more than what XML Schema does, XSD not a limitation
  • Can facilitate reuse of artifacts
    • Simpler artifacts
    • Lower bar to entry
  • Renders that are:
    • Simpler
    • Are targeted to a specific dev environment
    • Could be UML, XML Schema, whatever

Does it cause any problems

  • It's new
    • Tools aren't going to support it
      • But it's just XML
      • Easier to make a tool work with it than to reverse engineer NIEM XML Schemas?
    • Complicated UML modeling tools are expensive
      • Not the NIEM Profile
      • But other forms of UML rendering
    • Cabral has NIEM-specific UML extensions for free tools
  • Claims it adds an unneeded level of complexity
    • NIEM Classic, can always just use the traditional XML Schema render

"We have a commit to support all parts of the niem livecycle using free and open source software." -- Dr. Scott

Where are we currently?

Metamodel Repo

metamodel.xml is the metamodel, as plain old XML.

Follows all the rules of NIEM conformance.

  • Basic code in place for this.
  • XSLT does the transformations to XML Schema
  • Based on unvetted decisions

What needs to be done?

  • Modules need building out
    • XML Schema => model transform (hard)
    • model => JSON schema transform (easy)
      • what's the base element?
      • need to track top-level info
    • human readable documentation
    • content by inclusions vs by reference?
  • Things not handled
    • Metadata
    • Roles?
    • Associations just use the existing NIEM class

Rendering Targets

  • XML Schema
  • "Simple" XML Schema
  • JSON/JSON-LD
  • SQL
  • CSV
  • UML (via XMI)
  • OWL
  • OpenAPI
  • human readable documentation
    • Text
      • HTML
      • Markdown
      • RTF
      • PDF
    • Diagrams
      • DOT
      • Mermaid

What are the roadblocks?

  • Verbose and not as simple as maybe it could be?
  • Needs JSON Schema help
    • JSON would be a good first win
  • XMI is another early win
    • But isn't great as a format

Is the current metamodel model good enough? Is there a different way of doing things?

Who can help?

  • JSON: Dr. Scott?
  • UML: Jim Cabral?

Profiles

How do we talk about profiles of models? Is it just a smaller version of a model or is it a thing that talks about models?

What do the pieces of a subset of this model look like, including tightening cardinality?

Does this end up looking like the wantlist?

What about a list of exclusions? I want everything except A, B, and C.

Naming (Data Element Management)

How can we keep component names in a way that maintains the meaning we put into them?

Simplest would be mixed content, but we don't want to go there.

There some stuff in ISO-11179.

Move some of NDR stuff to the metamodel, especially the naming?