Component-based Webgis

The characteristic of the GIS is distribution, opening and flexibility of the space. From the constitution of GIS, the structure of data and the construction of software that sustained to calculation models are the two important aspects of it, and that decide the develop trend of GIS. Distribution of data and component of software is GIS's primary develop trend, that also illuminate that the appearance of WebGIS is the necessity of applied requirement. Component WebGIS is a new form composed by software that under distribution condition. That is the basic of practice from "number city" to "number globe", and that the mostly content of basic establish construct of state geography. Moreover, that is the efficacious attempt of software gridding of geography information.1.Organization by space dataThe structure data and non-structure data of WebGIS are concomitant. Relation database put up deficiency to express and storage space which attribute to non-configuration data. OODB have great adaptability to them, however, they still juvenility in theory and technique. It is significant meaning and practical value, according to the characteristics of space data and attribute data, that the idea and ideology based on relation database introjecting object database probed into the theory of ORDB especial storage model on achieving techniques or uniting data which offering faced object operation founded on defining non-structure data meaning and that accomplishing efficient organization in data of WebGIS model. In this thesis, the frondose work in WebGIS data organization can be generalized under three aspects:(1) It is established uniform theoretics foundation for structure of space data that based on having space object conception models which picking up three dimension analyse E-R model, therefore offering geography space data model.(2) The relation description to space database object of WebGIS that adopting three table structure frame have set forth the design to every table.(3) It bring forward multi-data fountain integration precept based on ODBC and WebGIS space data distributing accessing that aimed at WebGIS distributing.2.Implement on componentComponent technical is good technique to implement WEB applied platform. The important investigate matter of component WebGIS is studing how to put up component partition of WebGIS and relation structure of it, presenting system structure of WebGIS so that making it fit the needs of distributing surroundings by analyzing component form and character of WebGIS, that founded on DCOM which having been standard. The particular work on WebGIS component aspect can be generalized with these:(1) Illuminate the operating mechanism of component and sustaining model of distributing software frame.(2) To show the component form and trait of WebGIS, and to plot out composing arrangement of components, sequentially, to come into being the interrelated organization frame of components.(3) Make the component becoming three major kinds and six minor kinds and describe detailedly the constitutes and foundation of them.(4) To bestow system structure model of WebGIS founded on components.