Meta-Object Facility

<h2 id="overview">Overview</h2>
<p>MOF was developed to provide a <a href="/facts/Type_system/Tz0bAMS9">type system</a> for use in the <a href="/facts/CORBA/VUDlTHs5">CORBA</a> architecture, a set of schemas by which the structure, meaning and behaviour of objects could be defined, and a set of CORBA interfaces through which these schemas could be created, stored and manipulated.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> 
</p><p>MOF is designed as a four-layered architecture. It provides a meta-meta model at the top layer, called the M3 layer. This M3-model is the language used by MOF to build metamodels, called M2-models. The most prominent example of a Layer 2 MOF model is the UML metamodel, the model that describes the UML itself. These M2-models describe elements of the M1-layer, and thus M1-models. These would be, for example, models written in UML. The last layer is the M0-layer or data layer. It is used to describe real-world objects.
</p><p>Beyond the M3-model, MOF describes the means to create and manipulate models and metamodels by defining <a href="/facts/CORBA/VUDlTHs5">CORBA</a> interfaces that describe those operations. Because of the similarities between the MOF M3-model and UML structure models, MOF metamodels are usually modeled as UML class diagrams. 
</p>
<h3>File formats</h3>
<p>A conversion from MOF specification models (M3-, M2-, or M1-Layer) to W3C XML and XSD are specified by the <a href="/facts/XML_Metadata_Interchange/JQneoWnQ">XMI</a> (ISO/IEC 19503) specification. XMI is an XML-based exchange format for models.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>: xi 
</p><p>From MOF to Java™ there is the Java Metadata Interchange (JMI) specification by <a href="/facts/Java_Community_Process/LFQVV4Ik">Java Community Process</a>.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>: xi 
</p><p>It also provides specs to make easier automatic CORBA IDL interfaces generation.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>: 3 
</p>
<h2 id="metamodeling-architecture">Metamodeling architecture</h2>
<p>MOF is a <i>closed</i> metamodeling architecture; it defines an M3-model, which conforms to itself. MOF allows a <i>strict</i> meta-modeling architecture; every model element on every layer is strictly in correspondence with a model element of the layer above. MOF only provides a means to define the structure, or <a href="/facts/Abstract_syntax/dDs6XLtx">abstract syntax</a> of a language or of data. For defining metamodels, MOF plays exactly the role that <a href="/facts/EBNF/89KI2QTe">EBNF</a> plays for defining programming language grammars. MOF is a <a href="/facts/Domain_Specific_Language/n18H1foD">Domain Specific Language</a> (DSL) used to define metamodels, just as EBNF is a DSL for defining grammars. Similarly to EBNF, MOF could be defined in MOF.
</p><p>In short, MOF uses the notion of MOF::Classes (not to be confused with UML::Classes), as known from <a href="/facts/Object-oriented_programming/TxNMEcao">object orientation</a>, to define concepts (model elements) on a metalayer. MOF may be used to define object-oriented metamodels (as <a href="/facts/Unified_Modeling_Language/3tlNS0tH">UML</a> for example) as well as non object-oriented metamodels (e.g. a <a href="/facts/Petri_net/BK7eTHNm">Petri net</a> or a <a href="/facts/Web_Service/qxrwqB3D">Web Service</a> metamodel). 
</p><p>As of May 2006, the <a href="/facts/Object_Management_Group/SNpN8n9U">OMG</a> has defined two compliance points for MOF:
</p>
<ul><li>EMOF for Essential MOF<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></li>
<li>CMOF for Complete MOF<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></li></ul>
<p>In June 2006, a <i>request for proposal</i> was issued by OMG for a third variant, SMOF (Semantic MOF).
</p><p>The variant ECore that has been defined in the <a href="/facts/Eclipse_Modeling_Framework/Hd939zYh">Eclipse Modeling Framework</a> is more or less aligned on OMG's EMOF. 
</p><p>Another related standard is <a href="/facts/Object_Constraint_Language/coIhRpJb">OCL</a>, which describes a formal language that can be used to define model constraints in terms of <a href="/facts/Predicate_logic/lcISqWIg">predicate logic</a>.
</p><p><a href="/facts/QVT/hjP6P8Cj">QVT</a>, which introduces means to query, view and transform MOF-based models, is a very important standard, approved in 2008.  See <a href="/facts/Model_Transformation_Language/TzNkMsEn">Model Transformation Language</a> for further information.
</p>
<h2 id="international-standard">International standard</h2>
<p>MOF is an international standard:
</p>
MOF 2.4.2
<a href="/facts/International_Organization_for_Standardization/IacYR7Yg">ISO</a>/<a href="/facts/International_Electrotechnical_Commission/hSK0kjwI">IEC</a> 19508:2014 Information technology — Object Management Group Meta Object Facility (MOF) Core
MOF 1.4
<a href="/facts/International_Organization_for_Standardization/IacYR7Yg">ISO</a>/<a href="/facts/International_Electrotechnical_Commission/hSK0kjwI">IEC</a> 19502:2005 Information technology — Meta Object Facility (MOF)
<p>MOF can be viewed as a standard to write <a href="/facts/Metamodeling/lA2nkA6J">metamodels</a>, for example in order to model the abstract syntax of <a href="/facts/Domain_Specific_Language/n18H1foD">Domain Specific Languages</a>. <a href="/facts/Kermeta/EP5BKJHA">Kermeta</a> is an extension to MOF allowing executable actions to be attached to EMOF meta-models, hence making it possible to also model a DSL operational semantics and readily obtain an interpreter for it.
</p><p><a href="/facts/Java_Metadata_Interface/ddrcRL3Y">JMI</a> defines a Java API for manipulating MOF models.
</p><p>OMG's MOF is not to be confused with the Managed Object Format (MOF) defined by the <a href="/facts/Distributed_Management_Task_Force/rIh0qDbI">Distributed Management Task Force</a> (DMTF) in section 6 of the Common Information Model (CIM) Infrastructure Specification, version 2.5.0.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a>
</p>
<h2 id="see-also">See also</h2>

<ul><li><a href="/facts/Common_Warehouse_Metamodel/LMLXyAub">Common Warehouse Metamodel</a></li>
<li><a href="/facts/Domain-specific_language/n18H1foD">Domain-specific language</a></li>
<li><a href="/facts/Kermeta/EP5BKJHA">Kermeta</a></li>
<li><a href="/facts/KM3/sDnUKBBg">KM3</a></li>
<li><a href="/facts/Metamodeling/lA2nkA6J">Metamodeling</a></li>
<li><a href="/facts/Metadata/qt35z79C">Metadata</a></li>
<li><a href="/facts/Model-driven_architecture/IY0daKp1">Model-driven architecture</a></li>
<li><a href="/facts/OGML/gqQqTyRj">OGML</a></li>
<li><a href="/facts/Platform-specific_model/R04WWb8h">Platform-specific model</a></li>
<li><a href="/facts/QVT/hjP6P8Cj">QVT</a></li>
<li><a href="/facts/SPEM/RPSASyxy">SPEM</a></li>
<li><a href="/facts/XML_Metadata_Interchange/JQneoWnQ">XML Metadata Interchange</a></li></ul>

<h2 id="further-reading">Further reading</h2>
<ul><li>Official MOF specification from OMG</li>
<li>Ralph Sobek, MOF Specifications Documents</li>
<li>Johannes Ernst, <i>What is metamodeling?</i></li>
<li>Woody Pidcock, <i>What are the differences between a vocabulary, a taxonomy, a thesaurus, an ontology, and a meta-model?</i></li>
<li>Anna Gerber and Kerry Raymond, MOF to EMF and Back Again.</li>
<li>Weaving Executability into Object-Oriented Meta-Languages</li>
<li>MOF Support for Semantic Structures RFP Request For Proposal on SMOF</li></ul>
<h2 id="external-links">External links</h2>

Wikimedia Commons has media related to Meta-Object Facility.

<ul><li><a href="http://www.omg.org/mof/">OMG's MetaObject Facility</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>"OMG Meta-Object Facility (MOF) Core Specification, Version 2.4.1". Object Management Group. p. 1. Retrieved 17 February 2014. <a href="http://www.omg.org/spec/MOF/2.4.1/PDF" target="_blank">http://www.omg.org/spec/MOF/2.4.1/PDF</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"Common Facilities RFP-5: Meta-Object Facility" (PDF). Object Management Group. 2 May 1996. Retrieved 14 January 2014. <a href="http://www.omg.org/cgi-bin/doc?cf/96-05-02.pdf" target="_blank">http://www.omg.org/cgi-bin/doc?cf/96-05-02.pdf</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>"OMG Meta-Object Facility (MOF) Core Specification, Version 2.4.1". Object Management Group. p. 1. Retrieved 17 February 2014. <a href="http://www.omg.org/spec/MOF/2.4.1/PDF" target="_blank">http://www.omg.org/spec/MOF/2.4.1/PDF</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>"OMG Meta-Object Facility (MOF) Core Specification, Version 2.4.1". Object Management Group. p. 1. Retrieved 17 February 2014. <a href="http://www.omg.org/spec/MOF/2.4.1/PDF" target="_blank">http://www.omg.org/spec/MOF/2.4.1/PDF</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>"OMG Meta-Object Facility (MOF) Core Specification, Version 2.4.1". Object Management Group. p. 1. Retrieved 17 February 2014. <a href="http://www.omg.org/spec/MOF/2.4.1/PDF" target="_blank">http://www.omg.org/spec/MOF/2.4.1/PDF</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>"OMG Meta-Object Facility (MOF) Core Specification, Version 2.4.1". Object Management Group. p. 1. Retrieved 17 February 2014. <a href="http://www.omg.org/spec/MOF/2.4.1/PDF" target="_blank">http://www.omg.org/spec/MOF/2.4.1/PDF</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>"OMG Meta-Object Facility (MOF) Core Specification, Version 2.4.1". Object Management Group. p. 1. Retrieved 17 February 2014. <a href="http://www.omg.org/spec/MOF/2.4.1/PDF" target="_blank">http://www.omg.org/spec/MOF/2.4.1/PDF</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Common Interface Model (CIM) Interface Structure, version 2.5.0 <a href="http://www.dmtf.org/standards/published_documents/DSP0004_2.5.0.pdf" target="_blank">http://www.dmtf.org/standards/published_documents/DSP0004_2.5.0.pdf</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
</ol>

Meta-Object Facility open-in-new

Meta-Object Facility