1. Meta Level
2. Brief Introduction of UML

OMG (Object Management Group) is well-known as the group constituting the CORBA (Common Object Request Broker Architecture), which is a basic technology of distributed object. Today, in addition to CORBA, OMG focuses on UML-centralized and modeling-related technologies. The technology is shown in Figure 1. UML includes the technology of defining MOF (Meta Object Facility) elements, and MOF is also adopted in UML. The so-called elements refer to the basic elements like text type, integer type or class, association, etc. MOF is not limited to UML; it also defines basic CORBA like IDL interface, Exception, etc. The next layer of UML defines the labeling method of presentation model. The layer after the next is the object model under actual design and analysis. In this layer, system developers conduct systematic analysis and design. In the OMG modeling technologies, the operation begins from the applied object to M0, M1, M2 and M3.

OMG has conceived an extended UML structure, which is called the UML Profile. Nowadays, we can find UML Profile for CORBA, UML Profile for EDO (Enterprise Distributed Object Computing), UML Profile for Schedule, Performance and Time and so on. They are adopted for CORBA, distributed object computing, real-time expansion and combination. In order to exchange UML models between Cases, XML (XML meta-data interchange) is developed. XML is not limited to model information; it can also take ordinary data as an object. The data structure is presented in the form of meta, and then converted into XML based on XML technologies. The scope of application includes exchange of data in the database, interactivity of medical data and information communication with EDI. UML, MOF, XMI, which comply with ISO specifications, are all adopted as international standards. They are not limited to the field of object technology, but can be extended as standards in all fields.