Welcome!
What is ORM? ORM is an acronym for "Object-Role Modeling" and is a way to build formal information models from which other artefacts can be automatically derived. For example, an object-role model can be used to generate a class model, a relational model and an entity relationship diagram. These artefacts can then be transformed into directly usable artefacts such as a physical database.
ORM is easy to use because it has only one data structure - the fact type. This simplicity is supported by a comprehensive set of constraint types that allow you to design complex information models.
ORM tools have built in "verbalizers" that generate easy-to-understand natural language from a graphical object-role model. This makes it easy for a non-technical person to validate the content of an object-role model. In contrast, if a non-technical person wants to understand a UML or entity-relationship (ER) model, the person must first learn the UML or ER language.
Thus, ORM provides a simpler, more accurate and more powerful approach to information modeling than other approaches such as Entity-Relationship modeling and UML.
What is the history of ORM? The roots of ORM can be traced to research into semantic modeling for information systems in Europe during the 1970's. There were many pioneers and this short summary does not by any means mention them all. An early contribution came in 1973 when M Senko wrote about "data structuring" in the IBM Systems Journal. In 1974 JR 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".
Other contributors in continental Europe introduced the "circle-box" notation and an early version of the conceptual schema design procedure. Other people added subtyping, and conceptual query ideas.
The first full formalization came in 1989 when Terry Halpin completed his PhD thesis on ORM. Terry also introduced extensions. In 1989, Terry Halpin and GM Nijssen co-authored the book "Conceptual Schema and Relational Database Design".
How can I learn more? The authoritative book on ORM is Terry Halpin's 2008 "Big Brown Book" entitled "Information Modeling and Relational Databases - Second Edition". (The first edition was published in 2001). You can order the Big Brown Book by clicking on the "Second Edition" image (see sidebar - Books). You can read about ORM from the documents in the Library. You can also participate in the Forum.
Are there any ORM 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 called "Microsoft Visio for Enterprise Architects".
In the same year, a companion "how to" book was published by Morgan Kaufmann entitled "Database Modeling with Microsoft Visio for Enterprise Architects". (see sidebar) Microsoft has retained the ORM functionality in the high-end version of Visual Studio 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). You can download the latest release of NORMA from the tools section in the Library.
Forum The Forum is for discussing ORM related topics. Vistors can see most of the discussions but to participate you have to register on the site. Not all discussions are visible to all registered members because they are for specialised sub-groups. However, if you don't see a topic that you feel should be given its own Forum, please post a message in the "Request a Topic" Forum. Your post should include a title, a description of the scope, how it relates to ORM and why you think that the ORM community will find it of interest.
Library You can download ORM software, ORM tutorials and ORM related documents from the Library. Most documents are in PDF format but there are also multimedia file types.
Research The research page supports ORM research. You can see the experimental material that I used in my 2008 MSc dissertation project. This experiment was designed to test the hypothesis that “ORM based methods require at least 25% less effort than alternative methods such as UML and ER.”
Visitors may browse the Library and Forum. Registered members can download documents and participate in the forum discussions. Registration is free - just click on the "Join" button at the top right of the screen and follow the instructions. If you experience a problem, please send a description of the problem to admin@ormfoundation.org.
Thank you for visiting The ORM Foundation website.
Ken Evans
What's New
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[quote user="OrionB"]Introduce an entity for this logging information, and attach the elements you wish included, with a spanning uniqueness constraint across all of them as the primary identifier.[/quote] That's the way I would do it, and contrary to what Matt says, if you do it on objects that will be tables, it doesn't seem to affect...
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Thanks, Terry, I'll look forward to seeing these abilities grow over time.
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Hi Thomas, This has been a feature of all of Terry's ORM tools since InfoModeler was announced in the early 1990's. This is also the case with NORMA. With NORMA, the procedure for generating a relational model and then generating the DDL is explained in Tutorial 1 which you can download from the Library. A description of the relational procedure...
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What are the necessary steps needed to generate a uniqueidentifier for a primary key column at the ORM level. The data set type is not available, unless I'm missing something. Thanks :) Thomas
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Hi Ken, Thanks for the quick message. I have been toying with the VisoModeller 3.1 for a while without any problems as I can use the ODBC driver. NORMA with ODBC would be more than sufficient - Sybase iAnywhere would obviously be a bonus. It seems wierd as VisioModeller (more than 10 years old) currently offers more in this area (sql generation possibilities...