Object–role modeling: Difference between revisions

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{{Short description|Programming technique}}

:''Not to be confused with [[Object-relational mapping]].

{{Distinguish|Object–relational mapping}}

The designer of a [[database]] builds a formal [[model (abstract)|model]] of the [[software application|application]] area or [[universe of discourse]] (UoD). The model requires a good understanding of the UoD and a means of specifying this understanding in a clear, unambiguous way. '''Object-Role Modeling (ORM)''' simplifies the design process by using [[natural language]], as well as intuitive [[diagram]]s which can be populated with examples, and by examining the information in terms of simple or elementary facts. By expressing the model in terms of natural concepts, like objects and roles, it provides a conceptual approach to modeling. Its attribute-free approach promotes semantic stability.

[[File:ORM-diagram-tkz-orm.png|406px|thumb|Example of an ORM2 diagram]]

'''Object–role modeling''' ('''ORM''') is used to model the [[semantics]] of a [[universe of discourse]]. ORM is often used for [[data modeling]] and [[software engineering]].

ORM evolved from the ''Natural language Information Analysis Method'' (NIAM, also known as ''aN Information Analysis Method'') and ''Binary Relationship Modeling'', which were developed in [[Europe]] in the mid-[[1970s]]. Dr. [[Terry Halpin]] provided the first formalization of Object-Role Modeling.

An object–role model uses graphical symbols that are based on [[First-order logic|first order predicate logic]] and set theory to enable the modeler to create an unambiguous definition of an arbitrary universe of discourse. Attribute free, the predicates of an ORM Model lend themselves to the analysis and design of [[graph database]] models in as much as ORM was originally conceived to benefit relational database design.

ORM's rich graphic notation is capable of capturing many business rules that are typically unsupported as graphic primitives in other popular data modeling notations.

The term "object–role model" was coined in the 1970s and ORM based tools have been used for more than 30 years&nbsp;– principally for [[data modeling]]. More recently ORM has been used to model [[business rules]], XML-Schemas, [[data warehouse]]s, requirements engineering and web forms.<ref>{{Cite book | last = Jarrar | first = M. | title = Conceptual Modeling - ER 2007 | chapter = Towards Automated Reasoning on ORM Schemes | doi = 10.1007/978-3-540-75563-0_14 | series = Lecture Notes in Computer Science | volume = 4801 | pages = 181–197 | year = 2007 | bibcode = 2007LNCS.4801..181J | isbn = 978-3-540-75562-3 | citeseerx = 10.1.1.148.6251 }}</ref>

Various software tools exist to enter ORM schemas, and generate relational database schemas. These include Microsoft Visio for Enterprise Architects, CaseTalk, Infagon, and NORMA.

== History ==

NORMA (Neumont ORM Architect), an open source plug-in to Microsoft Visual Studio 2005, supports ORM 2 (second generation ORM), and maps ORM schemas to a variety of implementation targets, including relational DBMSs, object-oriented code, and XML schema. As of April 2006, NORMA (accessible at the SourceForge link [1] below) is in a prototype stage, but is evolving to a full production version.

The roots of ORM can be traced to research into semantic modeling for information systems in Europe during the 1970s. There were many pioneers and this short summary does not by any means mention them all. An early contribution came in 1973 when Michael Senko wrote about "data structuring" in the IBM Systems Journal. In 1974 Jean-Raymond Abrial contributed an article about "Data Semantics". In June 1975, [[Eckhard Falkenberg]]'s doctoral thesis was published and in 1976 one of Falkenberg's papers mentions the term "object–role model".

[[G.M. Nijssen]] made fundamental contributions by introducing the "circle-box" notation for object types and roles, and by formulating the first version of the conceptual schema design procedure. Robert Meersman extended the approach by adding subtyping, and introducing the first truly conceptual query language.

A graphical NIAM design tool which included the ability to generate database-creation scripts for Oracle, DB2 and DBQ was developed in the early 1990's in Paris. It was originally named Genesys and was marketed successfully in France and later Canada. It could also handle ER diagram design. It was ported to SCO Unix, SunOs, DEC 3151's and Windows 3.0 platforms, and was later migrated to succeeding [[Microsoft]] operating systems, utilising XVT for cross operating system graphical portability.

Object role modeling also evolved from the ''Natural language Information Analysis Method'', a methodology that was initially developed by the academic researcher, [[G.M. Nijssen]] in the Netherlands ([[Europe]]) in the mid-1970s and his research team at the Control Data Corporation Research Laboratory in Belgium, and later at the University of Queensland, Australia in the 1980s. The acronym '''NIAM''' originally stood for "Nijssen's Information Analysis Methodology", and later generalised to "Natural language Information Analysis Methodology" and ''Binary Relationship Modeling'' since G. M. Nijssen was only one of many people involved in the development of the method.<ref>{{cite book |last=Wintraecken |first=J. J. V. R. |date=1990 |orig-year=1987 |title=The NIAM information analysis method: theory and practice |series=Translation of: Informatie-analyse volgens NIAM |___location=Dordrecht; Boston |publisher=[[Kluwer Academic Publishers]] |isbn=079230263X |oclc=19554537 |doi=10.1007/978-94-009-0451-4 |s2cid=30209824 |url=https://books.google.com/books?id=iJaqCAAAQBAJ}}</ref>

A recent variation of ORM is referred to as FCO-IM. It distinguishes itself from traditional ORM in that it takes a strict communication oriented perspective. Rather than modelling the ___domain and its essential concepts, it purely models the grammar used to discourse about the ___domain.

In 1989, [[Terry Halpin]] completed his PhD thesis on ORM, providing the first full formalization of the approach and incorporating several extensions.

==External links==

*[http://msdn2.microsoft.com/en-us/library/aa290383(VS.71).aspx Object Role Modeling: An Overview (msdn.microsoft.com)]

*[http://www.orm.net orm.net]

*[http://www.ormcentral.com ormcentral.com]

*[http://www.objectrolemodeling.com objectrolemodeling.com]

*[https://sourceforge.net/projects/orm SourceForge ORM Project]

*[http://essentialstrategies.com/publications/modeling/niam.htm NIAM/ORM]

* [http://www.casetalk.com CaseTalk, The FCO-IM casetool]

* [http://www.sqlalchemy.org/ The Python SQL Toolkit and Object Relational Mapper]

Also in 1989, [[Terry Halpin]] and [[G.M. Nijssen]] co-authored the book "Conceptual Schema and Relational Database Design" and several joint papers, providing the first formalization of object–role modeling.

==References==

"Information Modeling and Relational Databases" written by Terry Halpin.

A graphical NIAM design tool which included the ability to generate database-creation scripts for Oracle, DB2 and DBQ was developed in the early 1990s in Paris. It was originally named Genesys and was marketed successfully in France and later Canada. It could also handle ER diagram design. It was ported to SCO Unix, SunOs, DEC 3151's and Windows 3.0 platforms, and was later migrated to succeeding [[Microsoft]] operating systems, utilising XVT for cross operating system graphical portability. The tool was renamed OORIANE and is currently being used for large data warehouse and SOA projects.

[[Category:Data modeling]]

Also evolving from NIAM is "''Fully Communication Oriented Information Modeling''" [[FCO-IM]] (1992). It distinguishes itself from traditional ORM in that it takes a strict communication-oriented perspective. Rather than attempting to model the ___domain and its essential concepts, it models the communication in this ___domain (universe of discourse). Another important difference is that it does this on instance level, deriving type level and object/fact level during analysis.

{{compu-sci-stub}}

Another recent development is the use of ORM in combination with standardised relation types with associated roles and a standard [[machine-readable dictionary]] and [[Taxonomy (general)|taxonomy]] of concepts as are provided in the [[Gellish English]] dictionary. Standardisation of relation types (fact types), roles and concepts enables increased possibilities for model integration and model reuse.

[[de:Object Role Modeling]]

[[nl:Object Role Modeling]]

== Concepts ==

[[File:Object-Role Model Overview.jpg|thumb|240px|right|Overview of object–role model notation, Stephen M. Richard (1999).<ref name="SMR99"/>]]

=== Facts ===

Object–role models are based on elementary facts, and expressed in [[diagram]]s that can be verbalised into natural language. A fact is a [[proposition]] such as "John Smith was hired on 5 January 1995" or "Mary Jones was hired on 3 March 2010".

With ORM, [[proposition]]s such as these, are abstracted into "fact types" for example "Person was hired on Date" and the individual propositions are regarded as sample data. The difference between a "fact" and an "elementary fact" is that an elementary fact cannot be simplified without loss of meaning. This "fact-based" approach facilitates modeling, transforming, and querying information from any ___domain.<ref name="orm.net">{{Cite web | url=http://www.orm.net/pdf/ORM2_TechReport1.pdf | title=ORM 2 Graphical Notation | access-date=2024-05-19}}</ref>

=== Attribute-free ===

ORM is attribute-free: unlike models in the [[entity–relationship model|entity–relationship]] (ER) and [[Unified Modeling Language]] (UML) methods, ORM treats all elementary facts as relationships and so treats decisions for grouping facts into structures (e.g. attribute-based entity types, classes, relation schemes, XML schemas) as implementation concerns irrelevant to semantics. By avoiding attributes, ORM improves semantic stability and enables verbalization into natural language.

=== Fact-based modeling ===

[[Fact-based modeling]] includes procedures for mapping facts to attribute-based structures, such as those of ER or UML.<ref name="orm.net"/>

Fact-based textual representations are based on formal subsets of native languages. ORM proponents argue that ORM models are easier to understand by people without a technical education. For example, proponents argue that object–role models are easier to understand than declarative languages such as [[Object Constraint Language]] (OCL) and other graphical languages such as [[Unified Modeling Language|UML]] class models.<ref name="orm.net"/> Fact-based graphical notations are more expressive than those of ER and [[Unified Modeling Language|UML]]. An object–role model can be automatically mapped to relational and deductive databases (such as [[datalog]]).<ref>{{Cite web|url=http://www.ormfoundation.org/files/folders/orm_2010/entry2360.aspx|archive-url=https://web.archive.org/web/20110413060716/http://www.ormfoundation.org/files/folders/orm_2010/entry2360.aspx|url-status=usurped|archive-date=April 13, 2011|title=P:11 Mapping ORM To Datalog - an Overview - The ORM Foundation|website=www.ormfoundation.org|access-date=May 31, 2020}}</ref>

=== ORM 2 graphical notation ===

ORM2 is the latest generation of object–role modeling. The main objectives for the ORM 2 graphical notation are:<ref>{{cite web|url=http://www.orm.net/pdf/ORM2.pdf |title=ORM 2 |access-date=April 22, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090219122007/http://orm.net/pdf/ORM2.pdf |archive-date=February 19, 2009 }} Halpin, T. 2005, 'ORM 2', On the Move to Meaningful Internet Systems 2005: OTM 2005 Workshops, eds R. Meersman, Z. Tari, P. Herrero et al., Cyprus. Springer LNCS 3762, pp. 676–87.</ref>

* More compact display of ORM models without compromising clarity

* Improved internationalization (e.g. avoid English language symbols)

* Simplified drawing rules to facilitate creation of a graphical editor

* Extended use of views for selectively displaying/suppressing detail

* Support for new features (e.g. role path delineation, closure aspects, modalities)

=== Design procedure ===

[[File:Schema for Geologic Surface.svg|thumb|360px|right|Example of the application of Object Role Modeling in a "Schema for Geologic Surface", Stephen M. Richard (1999).<ref name="SMR99">Stephen M. Richard (1999). [http://pubs.usgs.gov/of/1999/of99-386/richard.html Geologic Concept Modeling]. U.S. Geological Survey Open-File Report 99-386.</ref>]]

System development typically involves several stages such as: feasibility study; requirements analysis; conceptual design of data and operations; logical design; external design; prototyping; internal design and implementation; testing and validation; and maintenance. The seven steps of the conceptual schema design procedure are:<ref name="TH01">Terry Halpin (2001). [http://www.orm.net/pdf/ORMwhitePaper.pdf "Object-Role Modeling: an overview"]</ref>

# Transform familiar information examples into elementary facts, and apply quality checks

# Draw the fact types, and apply a population check

# Check for entity types that should be combined, and note any arithmetic derivations

# Add uniqueness constraints, and check arity of fact types

# Add mandatory role constraints, and check for logical derivations

# Add value, set comparison and subtyping constraints

# Add other constraints and perform final checks

ORM's conceptual schema design procedure (CSDP) focuses on the analysis and design of data.

== See also ==

* [[Concept map]]

* [[Conceptual schema]]

* [[Enhanced entity–relationship model]] (EER)

* [[Information flow diagram]]

* [[Ontology double articulation]]

* [[Ontology engineering]]

* [[Relational algebra]]

* [[Three-schema approach]]

== References ==

{{Reflist|2}}

== Further reading ==

* {{Citation

| last = Halpin | first = Terry

| author-link = Terry Halpin

| title = Conceptual Schema and Relational Database Design

| publisher = [[Prentice Hall]]

| place = Sydney

| year = 1989

| isbn = 978-0-13-167263-5}}

* {{Citation

| last1 = Rossi

| first1 = Matti

| last2 = Siau

| first2 = Keng

| title = Information Modeling in the New Millennium

| publisher = IGI Global

| date = April 2001

| isbn = 978-1-878289-77-3

| url-access = registration

| url = https://archive.org/details/informationmodel0000ross

}}

* {{Citation

| last1 = Halpin | first1 = Terry

| author-link = Terry Halpin

| last2 = Evans | first2 = Ken

| last3 = Hallock| first3 = Pat

| last4 = Maclean | first4 = Bill

| title = Database Modeling with Microsoft Visio for Enterprise Architects

| publisher = [[Morgan Kaufmann]]

| date = September 2003

| isbn = 978-1-55860-919-8 }}

* {{Citation

| last1 = Halpin | first1 = Terry

| author-link = Terry Halpin

| last2 = Morgan | first2 = Tony

| title = Information Modeling and Relational Databases: From Conceptual Analysis to Logical Design

| edition = 2nd

| publisher = [[Morgan Kaufmann]]

| date = March 2008

| isbn = 978-0-12-373568-3 }}

== External links ==

{{Commons category|Object role modeling}}

{{DEFAULTSORT:Object Role Modeling}}

[[Category:Data modeling]]

[[Category:Data modeling languages]]

[[Category:Modeling languages]]