The Meta-Object Facility (MOF) is an

Object Management Group The Object Management Group (OMG®) is a computer industry Standards Development Organization (SDO), or Voluntary Consensus Standards Body (VCSB). OMG develops enterprise integration and modeling standards for a range of technologies. Busin ...

(OMG) standard for model-driven engineering. Its purpose is to provide a

type system In computer programming, a type system is a logical system comprising a set of rules that assigns a property called a ''type'' (for example, integer, floating point, string) to every '' term'' (a word, phrase, or other set of symbols). Usu ...

for entities in the CORBA architecture and a set of interfaces through which those types can be created and manipulated. MOF may be used for domain-driven software design and object-oriented modelling.

Overview

MOF was developed to provide a

for use in the CORBA 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. 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. Beyond the M3-model, MOF describes the means to create and manipulate models and metamodels by defining CORBA 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.

File formats

A conversion from MOF specification models (M3-, M2-, or M1-Layer) to W3C XML and XSD are specified by the XMI (ISO/IEC 19503) specification. XMI is an XML-based exchange format for models. From MOF to Java™ there is the Java Metadata Interchange (JMI) specification by Java Community Process. It also provides specs to make easier automatic CORBA IDL interfaces generation.

Metamodeling architecture

MOF is a ''closed'' metamodeling architecture; it defines an M3-model, which conforms to itself. MOF allows a ''strict'' 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 abstract syntax of a language or of data. For defining metamodels, MOF plays exactly the role that EBNF plays for defining programming language grammars. MOF is a

Domain Specific Language A domain-specific language (DSL) is a computer language specialized to a particular application domain. This is in contrast to a general-purpose language (GPL), which is broadly applicable across domains. There are a wide variety of DSLs, ranging ...

(DSL) used to define metamodels, just as EBNF is a DSL for defining grammars. Similarly to EBNF, MOF could be defined in MOF. In short, MOF uses the notion of MOF::Classes (not to be confused with UML::Classes), as known from object orientation, to define concepts (model elements) on a metalayer. MOF may be used to define object-oriented metamodels (as UML for example) as well as non object-oriented metamodels (e.g. a Petri net or a

Web Service A web service (WS) is either: * a service offered by an electronic device to another electronic device, communicating with each other via the Internet, or * a server running on a computer device, listening for requests at a particular port over a n ...

metamodel). As of May 2006, the OMG has defined two compliance points for MOF: *EMOF for Essential MOF *CMOF for Complete MOF In June 2006, a ''request for proposal'' was issued by OMG for a third variant, SMOF (Semantic MOF). The variant ECore that has been defined in the Eclipse Modeling Framework is more or less aligned on OMG's EMOF. Another related standard is OCL, which describes a formal language that can be used to define model constraints in terms of

predicate logic First-order logic, also called predicate logic, predicate calculus, or quantificational logic, is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. First-order logic uses quantified variables ove ...

. QVT, which introduces means to query, view and transform MOF-based models, is a very important standard, approved in 2008. See Model Transformation Language for further information.

International standard

MOF is an international standard: ;MOF 2.4.2 :

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

/ IEC 19508:2014 Information technology — Object Management Group Meta Object Facility (MOF) Core ;MOF 1.4 :

/ IEC 19502:2005 Information technology — Meta Object Facility (MOF) MOF can be viewed as a standard to write metamodels, for example in order to model the abstract syntax of

s. Kermeta 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. JMI defines a Java API for manipulating MOF models. OMG's MOF is not to be confused with the Managed Object Format (MOF) defined by the

Distributed Management Task Force Distributed Management Task Force (DMTF) is a 501(c)(6) nonprofit industry standards organization that creates open manageability standards spanning diverse emerging and traditional IT infrastructures including cloud, virtualization, network, s ...

(DMTF) in section 6 of the Common Information Model (CIM) Infrastructure Specification, version 2.5.0.Common Interface Model (CIM) Interface Structure, version 2.5.0
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References

External links

OMG's MetaObject Facility
{{ISO standards Specification languages Data modeling Unified Modeling Language ISO standards