Research On Native Mode GML Spatial Data Management Mechanism

Spatial Data Management is very important research content in Geoinformatics, and is primarily research and development part to spatial infromation systems' vendors. It is efficient or not directly concerns to rise and decline of spatial information systems, concerns to the efficient use of spatial data, concerns to the development and application of spatial information technology.GML is a kind of novel, succinct, unified encoding international standard for spatial information under the Internet enviroment, which provides new methods and approaches for spatial data modeling, raster and vector unified GIS research, WebGIS research and development, spatial data sharing and interoperability research. As based on XML, GML has characteristics of textuality, self-description, extensibility, separability of content and presentation, openness, interoperability, which makes GML is extensively concerned, studied and practised, and meanwhile, lots of even mass GML spatial data are being produced. How to efficiently manage these GML data and then efficiently implement storage, index, query, transport and transformations to GML spatial data is a key problem to GML researchers and GML spatial data users, and also is a key problem to efficiently achieve, implement and carry out for GML spatial infromation systems, GML spatial infromation integration systems, GML spatial information sharing and interoperability systems. To GML spatial data management, there have two main categories: based on RDBMS and based on native XML Database. As the feature of level embeding model of GML data, using RDBMS to manage GML data is not perfect. And because of the feature of XML like data format, using native XML Database to manage GML spatial data has the vantages of birth. But the spatiality of GML data, navtive XML Database can not directly manage them, it must be extended. While seeing the research progress home and abroad, GML spatial data management, especially based on native XML Database is still in stage of scattered, partial and initiatory.This thesis mainly concerns the research on GML spatial data's storage, index, query, transport and transformations based on native mode, and its integration with application. As follows. (1) The general view of XML and geo-spatial data is given, the GML feature, GML schema and GML application schema are analysed. And according to GML specifications and modeling concepts, a two-dimensional campus modeling example is given. (2) The achitecture of Native GML Spatial Database System is researched, including concept, content and system achitecture. And the native mode storage model of GML spatial data is also researched, involving the correlativity and independence between GML instance data and GML application schema. (3) The indexing mechanism and algorithm of GML spatial data storage are researched. Combined with XML indexing encoding scheme, XML query structure join algorithm and traditional spatial data indexing algorithm, a kind of GML spatial data indexing mechanism based on Ex-Dewey prefix encoding and R-tree is proposed. (4) Native mode GML spatial data querying mechanism and query language are researched. Integrated with native mode GML spatial data indexing mechanism, GML spatial data query language based on XQuery is deeply researched and extended. (5) Efficient compression transport scheme of GML spatial data and transformations methods between GML data and KML data, or SVG format data are researched. (6) The integrating application of Native GML Spatial Database System and digital earth prototype system is researched. A kind of achitecture of native GGEarth spatial data application and service system is proposed. Its prototype system is designed in order to implement a new kind of spatial data application and service system involving functions with data displaying, querying, updating and analysing, which uses Native GML Database as the standard data center and the digital earth platform prototype system client as its front-end.The main research findings and innovations of this thesis are as follows. (1) A kind of achitecture of Native GML Spatial Database System is proposed. Its concept, system achitecture and content are detailedly given. And also element is ascertained as the storage granularity of native GML spatial data storage model. (2) A kind of Ex-Dewey prefix encoding scheme aiming at XML or GML non-spatial data indexing construction is proposed. Ex-Dewey encoding scheme eliminates Dewey encoding scheme's shortcoming of node's inserting and deleting effecting its following siblings' and corresponding descendants' nodes encoding, and proposes new updating strategy of node's inserting and deleting no effecting others' encoding value. It also keeps the advantages of Dewey encoding scheme. And a corresponding structure join algorithm - ED-XQ-SJ for XML or GML non-spatial data querying is proposed. The algorithm's idea, description and verification are given. The algorithm can directly determine the ancestors-descendants or parents-children relationship between potential ancestor node set and descendant node set, and do not access the real storage nodes. It reduces complexity, and obvious decreases the I/O overhead as well. (3) A kind of GML spatial data indexing mechanism based on Ex-Dewey prefix encoding and R-tree is proposed. It uses R-tree to construct spatial index for GML spatial data from GML instance document, and uses Ex-Dewey prefix encoding scheme to construct index for GML non-spatial data, they are independent but closely correlative, and together accomplish the indexing of GML data. (4) GML spatial data query language based on XQuery is deeply researched and extended, and named GXQuery. Based on research of former researchers, this thesis deeply researches GXQuery from reasons of extending XQuery, features of GML spatial data query language, spatial extending content of XQuery, system achitecture of GXQuery, implementation methods of GXQuery and query examples of GXQuery. It extends GML spatial data query language's constitution, content and application. (5) A kind of native GGEarth spatial data application and service system achitecture is proposed. Its main research content and key implementing techniques are given. And a GGEarth experimental system is developed, which has made experimental running for '5·12' Wenchuan Earthquake time sequence distribution and digital Jiuzhai virtual touring.