Object–role modeling: Difference between revisions

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{{Short description|Programming technique}}

{{Distinguish|object–relationalObject–relational mapping}}

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

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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.

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 journalbook | last = Jarrar | first = M. | doititle = 10.1007/978Conceptual Modeling -3-540-75563-0_14 ER 2007 | titlechapter = Towards Automated Reasoning on ORM Schemes | journaldoi = Lecture Notes in Computer Science10. Proceedings of the 26th International Conference on Conceptual Modeling1007/978-3-540-75563-0_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>

== History ==

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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 {{Bare| title=ORM 2 Graphical URLNotation PDF| access-date=March 20222024-05-19}}</ref>

=== Attribute-free ===

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[[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 ===

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* [[Ontology engineering]]

* [[Relational algebra]]

* [[Three -schema approach]]

== References ==

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== External links ==

{{Commons category|Object role modeling}}

* [http://www.ormfoundation.org The ORM foundation]

* [http://www.orm.net Terry Halpin's ORM site]

* [http://factmodeling.org FactModeling.org dedicated to Fact-Based Modeling]

{{DEFAULTSORT:Object Role Modeling}}