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UML Picture

In these articles, Dr. Halpin discusses the Unified Modeling Language within the context of Object Role Modeling (ORM) and shows how ORM models can be used in conjunction with UML models.







UML data models from an ORM perspective: Part 1 pdf file (66K)
Halpin, T. 1998, ‘UML data models from an ORM perspective: Part 1’, Journal of Conceptual Modeling, no. 1, www.inconcept.com.

Although the Unified Modeling Language (UML) facilitates software modeling, its object-oriented approach is arguably less than ideal for developing and validating conceptual data models with domain experts. Object Role Modeling (ORM) is a fact-oriented approach specifically designed to facilitate conceptual analysis and to minimize the impact on change. Since ORM models can be used to derive UML class diagrams, ORM offers benefits even to UML data modelers. This 10-part series provides a comparative overview of both approaches. Part 1 provides some historical background on both approaches, identifies several design criteria for modeling languages, and discusses how object reference and single-valued attributes are modeled in both.


UML data models from an ORM perspective: Part 2 pdf file (50K)
Halpin, T. 1998, ‘UML data models from an ORM perspective: Part 2’, Journal of Conceptual Modeling, no. 2, www.inconcept.com.

Second in a series of articles examining data modeling in UML from the perspective of ORM. This paper compares UML multi-valued attributes with ORM relationship types, including basic constraints on both. As part of this discussion, we also consider how these structures may be instantiated, using UML object diagrams or ORM fact tables.


UML data models from an ORM perspective: Part 3 pdf file (55K)
Halpin, T. 1998, ‘UML data models from an ORM perspective: Part 3’, Journal of Conceptual Modeling, no. 3, www.inconcept.com.

Third in a series of articles examining data modeling in UML from the perspective of ORM. This paper compares UML associations and related multiplicity constraints with ORM relationship types and related uniqueness, mandatory role and frequency constraints. It also contrasts instantiation of associations using UML object diagrams and ORM fact tables.


UML data models from an ORM perspective: Part 4 pdf file (53K)
Halpin, T. 1998, ‘UML data models from an ORM perspective: Part 4’, Journal of Conceptual Modeling, no. 4, www.inconcept.com.

Fourth in a series of articles examining data modeling in UML from the perspective of ORM, this paper examines associations in more detail, contrasting ORM nesting with UML association classes, and ORM co-referencing with UML qualified associations, then discusses exclusion constraints, and summarizes how the two methods compare with respect to terms and notations for data structures and instances.


UML data models from an ORM perspective: Part 5 pdf file (51K)
Halpin, T. 1998, ‘UML data models from an ORM perspective: Part 5’, Journal of Conceptual Modeling, no. 5, www.inconcept.com.

Fifth in a series of articles examining data modeling in the UML from the perspective of ORM, this paper discusses ORM subset and equality constraints, and how these may be specified in UML.


UML data models from an ORM perspective: Part 6 pdf file (56K)
Halpin, T. 1998, ‘UML data models from an ORM perspective: Part 6’, Journal of Conceptual Modeling, no. 6, www.inconcept.com.

Sixth in a series of articles examining data modeling in the UML from the perspective of ORM, this paper examines subtyping in ORM and in UML.


UML data models from an ORM perspective: Part 7 pdf file (47K)
Halpin, T. 1999, ‘UML data models from an ORM perspective: Part 7’, Journal of Conceptual Modeling, no. 7, www.inconcept.com.

Seventh in a series of articles examining data modeling in the UML from the perspective of ORM, this paper discusses some other graphic constraints (value, ring and join constraints.)


UML data models from an ORM perspective: Part 8 pdf file (54K)
Halpin, T. 1999, ‘UML data models from an ORM perspective: Part 8’, Journal of Conceptual Modeling, no. 8, www.inconcept.com.

Eighth in a series of articles examining data modeling in the UML from the perspective of ORM, this paper covers some recent updates to the UML standard, then discusses aggregation.


UML data models from an ORM perspective: Part 9 pdf file (51K)
Halpin, T. 1999, ‘UML data models from an ORM perspective: Part 9’, Journal of Conceptual Modeling, no. 9, www.inconcept.com.

Ninth in a series of articles examining data modeling in the UML from the perspective of ORM, this paper examines initial values and derived data in ORM and UML.


UML data models from an ORM perspective: Part 10 pdf file (55K)
Halpin, T. 1999, ‘UML data models from an ORM perspective: Part 10’, Journal of Conceptual Modeling, vol. 1, no. 10, www.inconcept.com.

Tenth in a series of articles examining data modeling in the UML from the perspective of ORM, this paper discusses changeability and collection types in UML and ORM.

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A comparison of UML and ORM for data modeling pdf file (138K)
Halpin, T. & Bloesch, A. 1998, ‘A comparison of UML and ORM for data modeling’, Proc. EMMSAD’98: 3rd IFIP WG8.1 Int. Workshop on Evaluation of Modeling Methods in Systems Analysis and Design, Pisa, Italy (June).

Although facilitating the transition to object-oriented code, UML's implementation concerns render it less suitable for developing and validating a conceptual model with domain experts. This can be remedied by using a fact-oriented approach for the conceptual modeling, from which UML class diagrams may be derived. This paper examines the relative strengths and weaknesses of UML and Object Role Modeling (ORM) for data modeling, and indicates how models in one notation can be translated into the other.


Data modeling in UML and ORM revisited pdf file (99K)
Halpin, T. 1999, ‘Data modeling in UML and ORM revisited’, Proc. EMMSAD’99: 4th IFIP WG8.1 Int. Workshop on Evaluation of Modeling Methods in Systems Analysis and Design, Heidelberg, Germany (June).

This paper further examines the relative strengths and weaknesses of ORM and UML for data modeling, focusing on attribute multiplicity, association arity, advanced constraints and subtyping. This analysis is given wider generality by addressing various language design principles (e.g. parsimony, orthogonality, convenience, expressibility) and illustrating how metamodel extensibility can be used to capture some features of one approach within the other.


Data modeling in UML and ORM: a comparison pdf file (159K)
Halpin, T. & Bloesch, A. 1999, ‘Data modeling in UML and ORM: a comparison’, Journal of Database Management, IGI Global, Hershey, USA.

This paper presents a detailed comparison of the conceptual data modeling capabilties of UML and ORM. It is based on the EMMSAD’98 conference paper listed above, but has been revised and extended for journal publication.


Augmenting UML with Fact-orientation pdf file (119K)
Halpin, T. 2001, ‘Augmenting UML with Fact-orientation’, Proc. IEEE Workshop on UML: a critical evaluation and suggested future, HICCS-34 conference, Maui, © 2000 IEEE.

This paper discusses various problems with UML (e.g. poor support for verbalization, weak constraint primitives, and multiplicity constraints that do not scale properly for n-aries) and shows how ORM can compensate for these deficiencies.


Evolving UML: Opportunities and Challenges

This slide presentation was included in the panel session “Research Issues for the Unified Modeling Language and Unified Process”, at the IRMA-2002 Conference held in Seattle May 2002. It includes links to several proposals for UML 2.0, and notes some weaknesss of UML class diagrams in comparision with ORM.


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