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A study on the component classification in GIS (Geographic Information System)
3. GIS Component Classification using Metadata
In order to classify GIS component, there are two views of classification; 1) The functional component classification [3], 2) The non-functional component classification. The functional component classification in GIS considers following 4 layers. First of all, Infrastructure Component, which describes general environment for developing component and executing such as various platforms, operation systems, and networks environment. Second, Data Provider Component, which has purpose to acquire interoperability among them constructed under heterogeneous environment, data provider component should be constructed. Third, Core / Base Component, which can be used as the kernel of GIS by developing certain GIS application software. There exist core components to perform general GIS functions such as Data Provider, Map Display, and Attribute Display also exists a base component to perform certain GIS functions such Network Analysis, 3D Analysis, and Authority. Forth, GIS Component, which shows several GIS domain such as MIS (Marketing Information System), FMS (Facility Management System), DCS(Disaster Control System), ITS(Intelligent Transformation System), UIS (Urban Information System), and LIS(Land Information System). Even though there are certain components having reusability and good quality, the rate of their reusability may be low because they have difficulty to access in a repository. It is essential to express the non-functional element to identify components. Here, two big non-functional classification categories are discussed such as GIS content-dependent metadata and GIS contents-independent metadata in Fig. 1.  Figure 1 Non-Functional Classification of GIS Component GIS content-dependent metadata: As you see in the item name, when metadata is associated with the original GIS domain itself, we call it GIS Content-dependent metadata. Especially, considering GIS component, there are three small categories related to it; 1) Identifier Attribute, 2) Service Attribute, 3) Support Data Attribute. On the other hand, GIS content-independent metadata: it doesn’t depend on the GIS domain. These kinds of metadata can be derived independently from the content of the GIS. There are seven small categories; 1) description Attribute, 2) Environment Attribute, 3) Development Attribute, 4) Restriction Attribute, 5) Supplier Attribute, 6) Quality Attribute, 7) Special Mention Attribute. In Fig. 2, the needs of individual GIS system developers tend to limit to what kinds of component they are accessing to on Web. System developers can obtain certain functionality presented to them in a way suiting their preferred style for its implementation. As the result, they can save their time, effort, and cost through on-line adaptation of GIS component in a repository. At this time, Metadata query broker is working as a brokerage mechanism supplied in the repository for the retrieval of various types component. As stated before the original purpose of these metadata query broker is to search the component that is usually associated with implementation of GIS application. Especially, to avoid storing multiple copies in a repository, each component should be registered through CUID.  Figure 2 On-line Adaptation of GIS Component |