Return to BRG Response Overview

Metamodel Response Points

This section contains the point-by-point response (comparison) between the two metamodels.

1. The Origins of a Business Rule ~ part 1

1.1 Relating rules to policies

• The BRG model permits business rules to be related to policy.
• The MDC model does not appear to provide this relationship.

1.2 Business Rule Statement vs. Business Rambling

• The BRG model uses the term "Business Rule Statement" for the concept.
• The MDC model uses the term "Business Rambling" for the concept.

  We initially considered the popular 'rambling' term for the concept but discarded it (because of its somewhat negative tone).

1.3 Business Rambling to Business Rule multiplicity (MDC model)

• The BRG model permits a Business Rule Statement to be related to many Business Rules (and vice versa).
• The MDC model restricts the multiplicity of Business Rambling to Business Rule to "at most 1"; this is incorrect (ref. MDC definition text).

2. The Origins of a Business Rule ~ part 2

2.1 Formal Expression Type / Formal Rule Statement vs. the MDC Grammar Model

If we understand the nature of the MDC's proposed Grammar Model, it appears to correspond to the intent of this portion of our model, but in more detail.

During the development of our model, we spent some time modeling grammars but abandoned that activity. Instead, the main point we chose to emphasize in our model is that

(a) one business rule may be expressed in multiple (language-specific) grammars, and

(b) this submodel does not impact or determine the essential statement (specification) of the business rule.

In other words, we would treat "grammar" as a set of language bindings. There is no one, single grammar.

Rather, we consider the essential statement of the business rule is in its conceptual model (i.e., the detail of its definition in terms of the metamodel constructs of "Business Rule.")

3. Business Rule Types ~ Core Taxonomy

3.1 Kinds of Business Rule

• The BRG model subtypes "Business Rule" into: Structural Assertion, Action Assertion, and Derivation, and then further subtypes Structural Assertion into Term and Fact.
• The MDC model has flattened the initial set of types to: TermRule, FactRule, ActionRule, and InferenceRule. This omits our generalization of Term and Fact into Structural Assertion. Therefore, there is no explicit representation of the "Structural Assertion" concept on the MDC model.

3.2 Derivation (BRG) vs. InferenceRule (MDC)

• The BRG model subtypes Derivation into Mathematical Calculation and Inference.
• The MDC model appears to have removed the distinction between the concepts of deriving knowledge by algorithm (Mathematical Calculation) vs. by reasoning (Inference).

  Furthermore, the MDC model has relabeled the general (supertype) concept as "InferenceRule" -- i.e., uses the label of one of its subtypes on the BRG model.

4. Structural Assertions ~ Term in Context

4.1 Terms in Context

• The BRG model provides for the ability to define a term in various contexts. (It also provides for common terms -- those which have a generally-understood interpretation, regardless of context.)
• The ability to relate a term to one or more contexts was mentioned in the Workshop but is not evident on the MDC model.

4.2 Terms and Synonyms

• The BRG model provides for a term to be a synonym of another term.
• The ability to define multiple terms for a concept (I.e., terms as synonyms) was mentioned in the Workshop but is not evident on the MDC model.

5. Structural Assertions ~ Kinds of Term

5.1 Terms as Types or Literals

• The BRG model makes explicit the ability to distinguish a term as either a 'type' or a 'literal.'
• The MDC model does not appear to reflect this.

5.2 Further subtypes of Type

• The BRG model further subtypes 'Type' into additional concepts that are often used in expressing rules (especially the notion of the system 'clock').
• The MDC model does not appear to reflect this.

5.3 Relating Type and Literal

• The BRG model expresses the ability to relate a 'type' with one or more 'literals' (i.e., to declare the set of 'valid values' for a datatype/domain).
• The MDC model does not appear to reflect this.

6. Structural Assertions ~ Terms and Facts

6.1 The structuring of Terms into Facts

• The BRG model permits the deep-structured semantics of a Fact to be captured in the conceptual model.
• The MDC model appears to omit this.

  (Note: during the Workshop, reference was made to another OIM submodel -- the Semantics Model. This additional submodel should be reviewed to see if these important constructs are accommodated in another part of the OIM.)

7. Structural Assertions ~ Kinds of Fact

7.1 Fact taxonomy

• The BRG model classifies Fact into subtypes: Attribute, Generalization, and Participation. It further subtypes Participation into Association, Aggregation, and Role.
• While not called out as explicit types on the MDC model, the MDC's documentation indicates that this general capability is provided via a property of FactRule. The documentation implies that the valueset of this property is extensible.

7.2 Operation as a kind of Fact

• The MDC model includes "Feature" which is either an Attribute or an Operation.
• The BRG model omits Operation as a kind of Fact.

8. Derivations & Facts

8.1 Derivation (AKA the MDC model's InferenceRule)

• The BRG model includes relationships that permit the composition of the derivation to be specified.
• The MDC model does not appear to support this.

9. Action Assertions

9.1 Action Assertion (AKA the MDC model's ActionRule)

• The BRG model includes relationships that permit the statement of an Action Assertion to be specified.
• The MDC model does not appear to support this.

10. Action Assertions ~ Categorization (1)

10.1 Action Assertion: basic classification

• The BRG model supports three basic types of Action Assertion.
• This basic classification appears to be recognized in the MDC model (it is discussed in the narrative), but it is not apparent how this is handled.

11. Action Assertions ~ Categorization (2)

11.1 Action Assertion: classification of the degree of control

• The BRG model provides for distinguishing Action Assertions that are controlling in the system from those that merely provide guidance.
• The MDC ActionRules does not appear to support this distinction.

12. Action Assertions ~ Categorization (3)

12.1 Action Assertion alternative classification(s)

• The BRG model illustrates that Action Assertions need to be classified in various other kinds of classification schemes. We have illustrated this on the model with a selection of the subtypes from the taxonomy of the Ross Method.
• The MDC ActionRules does not appear to support this ability to have user-defined classification schemes for "rules."