Object-Role Modeling

Not to be confused with Object-relational mapping.
Example of the application of Object Role Modeling in a "Schema for Geologic Surface", Stephen M. Richard (1999).[1]

Object Role Modeling (ORM) is a method for conceptual modeling, and can be used as a tool for information and rules analysis, ontological analysis, and data modeling in the field of software engineering.[2]

Contents

Overview

Object Role Modeling is a fact-oriented method for performing systems analysis at the conceptual level. The quality of a database application depends critically on its design. To help ensure correctness, clarity, adaptability and productivity, information systems are best specified first at the conceptual level, using concepts and language that people can readily understand. The conceptual design may include data, process and behavioral perspectives, and the actual DBMS used to implement the design might be based on one of many logical data models (relational, hierarchic, network, object-oriented etc.).[3]

The designer of a database builds a formal model of the 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 diagrams 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.

History

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.

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.

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

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. Since then Dr. Terry Halpin has authored six books and over 160 technical papers.

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 modeling the domain and its essential concepts, it purely models the grammar used to discourse about the domain. 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 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.

ORM2

example of an ORM2 diagram

ORM2 (second-generation ORM) is a new incarnation of Object-Role Modeling, supported by various modeling tools to support the new notation. Dr. Terry Halpin lead the effort of the NORMA ORM modeling tool spearheaded by Neumont University and currently through The ORM Foundation,[4] a UK-based non-profit organization dedicated to the promotion of the fact-oriented approach to information modeling

ORM2 leverages the work done by the BSBR group.

The main objectives for the ORM 2 graphical notation are:[5]

  • More compact display of ORM models without compromising clarity
  • Improved internationalization (e.g. avoid English language symbols)
  • Notation changes acceptable to a short-list of key ORM users
  • Simplified drawing rules to facilitate creation of a graphical editor
  • Full support of textual annotations (e.g. footnoting of textual rules)
  • Extended use of views for selectively displaying/suppressing detail
  • Support for new features (e.g. role path delineation, closure aspects, modalities)

The NORMA (Natural ORM Architect) tool is an open source project incorporating the ORM2 syntax.

Object role modeling topics

Graphic notation

Overview of the Object-Role Model notation, Stephen M. Richard (1999).[1]

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.

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

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.

The conceptual schema design procedure

The information system's life cycle typically involves several stages: feasibility study; requirements analysis; conceptual design of data and operations; logical design; external design; prototyping; internal design and implementation; testing and validation; and maintenance. ORM's conceptual schema design procedure (CSDP) focuses on the analysis and design of data. The seven steps of the conceptual schema design procedure:[3]

  1. Transform familiar information examples into elementary facts, and apply quality checks
  2. Draw the fact types, and apply a population check
  3. Check for entity types that should be combined, and note any arithmetic derivations
  4. Add uniqueness constraints, and check arity of fact types
  5. Add mandatory role constraints, and check for logical derivations
  6. Add value, set comparison and subtyping constraints
  7. Add other constraints and perform final checks

Tools

The growth of ORM has followed the availability of a series of steadily improving ORM tools.

The early ORM tools such as IAST (Control Data) and RIDL* were followed by InfoDesigner, InfoModeler and VisioModeler.

When Microsoft bought the Visio Corporation, Microsoft extended VisioModeler and made it a component of Microsoft Visual Studio. This was Microsoft's first ORM implementation and it was published in the 2003 Enterprise Architects release of Visual Studio as a component of the tool called "Microsoft Visio for Enterprise Architects (VEA)".

In the same year, a companion "how to" book was published by Morgan Kaufmann entitled "Database Modeling with Microsoft Visio for Enterprise Architects" .[6] Microsoft has retained the ORM functionality in the high-end version of Visual Studio 2005 and the Morgan Kaufmann book remains a suitable user guide for both versions.

The next "in the works" ORM tool is an open source tool called NORMA (Natural ORM Architect for Visual Studio).

DogmaModeler

DogmaModeler Screenshot.[7]

DogmaModeler is a free ontology modeling tool based on Object role modeling. The philosophy of DogmaModeler is to enable non-IT experts to model ontologies with a little or no involvement of an ontology engineer.

This challenge is tackled in DogmaModeler through well-defined methodological principles. The first version of DogmaModeler was developed at the Vrije Universiteit Brussel.

DogmaModeler open source status

The DogmaModeler Project[8] shows no activity since its creation in 2006, and the source code for the project is not available through that site. The latest version of the program, available at the http://jarrar.info/Dogmamodeler website is dated on October 27, 2006.

Since then the project seems to have been continued and expanded into several other tools at the Vrije Universiteit Brussel's Semantics Technology and Applications Research Laboratory (VUB STARLab).[9] A note on that site states "Users who only use DOGMAModeler for their own researches can contact (author's email) for the free download."[10]

VisioModeler

The former ORM tool known as VisioModeler is freely available as an unsupported product from Microsoft Corporation (as a 25 MB download). Models developed in VisioModeler may be exported to Microsoft's current and future ORM solutions. To obtain the free VisioModeler download, go to http://download.microsoft.com, search by selecting Keyword Search, enter the keyword "VisioModeler", select your operating system (e.g. Windows XP—Note: VisioModeler does NOT work under Windows Vista), change the setting for "Show Results for" to "All Downloads", and hit the "Find It!" button. This should bring up a download page that includes the title "VisioModeler (Unsupported Product Edition)". Clicking on this will take you to the link for the download file MSVM31.exe. Click on this to do the download.

Visio for Enterprise Architects (VEA)

Microsoft included a powerful ORM and logical database modeling solution within its Visio for Enterprise Architects (VEA) product. The 2005 release of VEA also included some minor upgrades (e.g. a driver for SQL Server 2005 was included).

CaseTalk

A modeling tool called CaseTalk[11] based on the ORM-dialect known as Fully Communication Oriented Information Modeling (FCO-IM) is available from Bommeljé Crompvoets en partners b.v., headquartered in Utrecht, The Netherlands. To find out more about this tool, check the CaseTalk website.

Infagon

A freeware ORM tool known as Infagon is available from Mattic software. Infagon is also based on the FCO-IM dialect. To download or obtain more details about this tool, click the Infagon home page.[12]

Other tools

  • Doctool and CogNIAM (CogNIAM tools).[13]
  • ActiveFacts (ORM 2 tools),.[14]
  • DogmaStudio (ORM Ontology tool),.[15]
  • Orthogonal Toolbox (free XML add-on to database modeling COM API for Microsoft's ORM solution).[16]

NORMA

NORMA (Natural ORM Architect for Visual Studio)[4] is a free and open source plug-in to Microsoft Visual Studio 2005, Visual Studio 2008 and Visual Studio 2010. It supports ORM 2 (second generation ORM), and maps ORM models to a variety of implementation targets, including major database engines, object-oriented code, and XML schema.

Dr. Terry Halpin's latest book, Information Modeling and Relational Databases, Second Edition [17] "...uses the notation of ORM 2 (second generation ORM), as supported by the NORMA (Neumont ORM Architect) tool..." (page 10), and "(...)At the time of writing, the Neumont ORM Architect (NORMA) tool provides the most complete support for the ORM 2 notation discussed in this book." (Preface, xxv).

NORMA Project status

As of April 2009, the NORMA project[18] delivers frequent releases and is almost ready to encompass the entire life-cycle of databases.

NORMA supports multiple generation targets including:

Database engines Microsoft Sql Server, Oracle, DB2, MySQL, PostgreSQL, etc.
Programming languages LINQ to SQL, PLiX (Programming Language in XML)[19] and PHP
Other XML schemas (XSD)

Advantages of NORMA are these:

  • Accepts typed input and automatically generates graphics
  • Validates common constraints and completeness as the model is entered
  • Provides simultaneous narrative and graphic versions of all models
  • Can provide E-R as well as ORM views of the model
  • Automatic navigation from error message to graphic view of the error
  • The three views (ORM, E-R, and narrative) provide comfortable access for most viewers. (Not everyone is comfortable with graphics, and the narrative view of the model is more quickly read by those who are comfortable with graphics.)
  • Can reverse-engineer a physical database (up to a point)
  • Narrative view uses hyperlinks for full cross-referencing
  • Graphic model has no fixed bounds
  • Automatic navigation from error message to graphic view of the error

See also

References

  1. ^ a b Stephen M. Richard (1999). Geologic Concept Modeling. U.S. Geological Survey Open-File Report 99-386.
  2. ^ Joachim Rossberg and Rickard Redler (2005). Pro Scalable .NET 2.0 Application Designs.. Page 27
  3. ^ a b Terry Halpin (2001). "Object-Role Modeling: an overview"
  4. ^ a b The ORM Foundation home page
  5. ^ http://www.orm.net/pdf/ORM2.pdf 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.
  6. ^ Halpin, Terry; Evans, Ken; Hallock, Pat; Maclean, Bill (September 2003), Database Modeling with Microsoft Visio for Enterprise Architects, Morgan Kaufmann, ISBN 978-1558609198 
  7. ^ DogmaModeler website
  8. ^ The DogmaModeler project at SourceForge
  9. ^ http://www.starlab.vub.ac.be/website/research
  10. ^ http://www.starlab.vub.ac.be/website/tools
  11. ^ http://www.casetalk.com/ The CaseTalk website
  12. ^ http://www.infagon.com
  13. ^ http://www.pna-group.com Doctool and CogNIAM (CogNIAM tools)
  14. ^ http://dataconstellation.com/ActiveFacts/ ActiveFacts
  15. ^ http://www.starlab.vub.ac.be/website/tools DogmaStudio
  16. ^ http://www.orthogonalsoftware.com/products.html Orthogonal Toolbox
  17. ^ Halpin, Terry; Morgan, Tony (March 2008), Information Modeling and Relational Databases: From Conceptual Analysis to Logical Design (2nd ed.), Morgan Kaufmann, ISBN 978-0123735683 
  18. ^ NORMA - The ORM Project at Sourceforge
  19. ^ http://sourceforge.net/projects/plix The PLiX Project at SourceForge

Further reading

  • Terry Halpin (2001), Object-Role Modeling: an overview
  • Terry Halpin (2005), ORM2 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.
  • Halpin, Terry (1989), Conceptual Schema and Relational Database Design, Sydney: Prentice Hall, ISBN 978-0131672635 
  • Rossi, Matti; Siau, Keng (April 2001), Information Modeling in the New Millennium, IGI Global, ISBN 978-1878289773 
  • Halpin, Terry; Evans, Ken; Hallock, Pat; Maclean, Bill (September 2003), Database Modeling with Microsoft Visio for Enterprise Architects, Morgan Kaufmann, ISBN 978-1558609198 
  • Halpin, Terry; Morgan, Tony (March 2008), Information Modeling and Relational Databases: From Conceptual Analysis to Logical Design (2nd ed.), Morgan Kaufmann, ISBN 978-0123735683 

External links


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