MOF is an extensible model driven integration framework for defining, manipulating and integrating metadata and data in a platform independent manner. MOF-based standards are in use for integrating tools, applications and data.1
The MetaObject Facility Specification is the foundation of OMG's industry-standard environment where models can be exported from one application, imported into another, transported across a network, stored in a repository and then retrieved, rendered into different formats (including XMI, OMG's XML-based standard format for model transmission and storage), transformed, and used to generate application code. These functions are not restricted to structural models, or even to models defined in UML - behavioral models and data models also participate in this environment, and non-UML modeling languages can partake also, as long as they are MOF-based.
The Meta Object Facility (MOF) provides a metadata management framework, and a set of metadata services to enable the development and interoperability of model and metadata driven systems. Examples of these systems that use MOF include modeling and development tools, data warehouse systems, metadata repositories, etc. A number of technologies standardized by OMG, including UML, MOF, CWM, SPEM, XMI, and various UML profiles, use MOF and MOF derived technologies (specifically XMI and more recently JMI that are mappings of MOF to XML and Java respectively) for metadata-driven interchange and metadata manipulation.
MOF has contributed significantly to some of the core principles of the emerging OMG Model Driven Architecture. Building on the modeling foundation established by UML, MOF introduced the concept of formal metamodels and Platform Independent Models (PIM) of metadata (examples include several standard OMG metamodels including UML, MOF itself, CWM, SPEM, Java EJB, EDOC, EAI, etc.) as well as mappings from PIMs to specific platforms (Platform Specific Models and mapping examples include MOF-to-IDL mapping in the MOF specification, MOF-to-XML DTD mapping in the XMI specification, MOF-to-XML Schema mapping in the XMI production of XML Schema specification, and MOF-to-Java in the JMI specification).