What is metadata [2005-01-13 01:28 PM | Author: zqss | from: [http://www.xcwww.cn] meta data describing the structure and meaning of data, as described in the application structure and processes Like the meaning. Remember: metadata is an abstract concept, with contexts, there are many uses in the development environment. Metadata is an abstract concept. When people describe the phenomenon of the real world, abstract information can be seen as metadata. For example, when describing the natural phenomena of wind, rain, and sunlight, it is necessary to use "weather" abstract concepts. It is also possible to further abstract summary of the weather by defining concepts such as temperature, precipitation and humidity. During the data design, you also use abstract terms to describe the various phenomena of the real world. People put people, locations, things, and digital organizations or designated as staff, customers or product data. During the software design, applications and database structures representing data or storage data can summarize metadata classification schemes that can be understood as developing and designers. Tables or forms are derived from objects, while the object is derived from class. There are multiple abstract concept levels in the metadata. A data instance can be described, and then the description itself will be described, then the following description will be described, which is constantly repeating until a certain actual limit is not described. Typically, metadata descriptions used in software development can be extended to an abstract concept of two to three. For example, "Loan Table" data instance can be described as a database table name. Database tables can also be described as database table objects. Finally, the database table object can be descriptated with an abstract class that determines that all derived objects must match the fixed feature collection. Metadata has contexts to distinguish between data and metadata distinguish between data and metadata. Model designers are expressed as types (such as various classes or relationships), while software developers are illustrative (such as Table class or Table Has Column). The difference between examples and types is related to the context. The metadata in one solution will become data in another scheme. For example, in a typical relational DBMS, the system directory will describe tables and columns that contain data. This means that the system catalog describes data definitions, so that data can be considered as metadata. However, as long as the correct software tool is used, these metadata can still be operated like other data. Examples of operating metadata include: viewing version control information of data along line or table, or a list of financial data is identified by searching for columns with currency data types. In this scenario, the standard metadata such as the system catalog becomes an operable data. Metadata has a variety of uses to use metadata types and instance information like any type of application or data design element. Expressing design information as metadata, especially standard metadata, can provide more possibilities for reuse, sharing, and multi-tool support.
