The Application of Classification and Indexing Technology of Component in GIS

The technology of reuse has been widely applied,of which the construction and administration of the component is the key.This paper discusses the discipline of the classification and matching of the component,and discusses one of the method-signature matching.This paper gives the plan of management of GIS component in the land administration domain. The major impediment to the industrialization of information technology is the enhancement of the quality and the productivity of the software.Software is currently considered as the key to the problem.Domain engineering and software architecture are introduced into the development of the GIS research.In the process of the combination with GIS,the following questions are the focus of the software engineers:how to utilize and represent the reusable GIS components efficiently and how to find the wanted GIS components from the large amount of GIS components in the reusable library.The research related to the first question deals with the issues such as GIS component model,stipulations of component,the data modeling of GIS component library and so on.The research related to the latter question deals with the issues such as the query interface of GIS component library,the matching of components,and the arithmetic of index and so on. The current methods of the representation and index of components can be categorized into the following three:the artificial intelligent method,the hypertext method and the indexing vocabularies method.A good classification method should describe the component precisely and be easily understood and utilized with high efficiency.The keyword classification method and the facet classification method have their own problems. The signature matching is pointed out by A.M.Zaremski and J.M.Wing.They named the characteristic information abstracted from the component signature.In the process of indexing,the request of the user should match the signature of the component.There are two classification of signature matching:function matching and module matching. After the domain analysis,we have the corresponding domain model in the domain of the administration of the land information,and build the tree-structure of the GIS reusable component library.In order to describe a GIS reusable component completely and reuse it efficiently,we present our methods which integrate both keyword classification and facet classification to describe a GIS component,and their data structure.The resolution of the query of GIS component library is also presented. There are many standards to justify the method of component indexing,such as efficiency,extension,etc.However,until now,none of indexing methods can satisfy all the requests of all the GIS users completely.A better resolution is to provide more than one indexing methods in a practical GIS system,which will become the important direction of the application of software reusable technology in the specific domain of GIS.The transaction of GIS components between different libraries and the representation and indexing of GIS component in a distributed multi-libraries are the central problems in the future.