(Information Center of Beijing Bureau of Land and Resources, Beijing, 1000 13)
This paper introduces the construction and application research of e-government information system from the aspects of system architecture, database design and management, and business application, and puts forward solutions and suggestions for the problems in the application process.
Keywords: land resources; E-government; Spatial data; workflow
At present, Beijing Municipal Bureau of Land and Resources adopts a top-down vertical management mechanism. In order to manage the land and resources under the jurisdiction of each administrative level, it is necessary to establish a scientific and complete data center and business platform, realize data sharing and functional coordination at all levels, ensure well-founded information and timely feedback, maximize the economic and social benefits of land and resources, and improve the management level of land and resources. E-government information system can manage the whole process of daily office business, from window connection to business closure and filing, and support various query statistics and map management. The system provides a comprehensive and all-round solution for the land and resources industry.
1 system architecture
The construction and management of land resources not only includes daily affairs, but also has dynamic characteristics that change with the change of management mode and management system. Therefore, the e-government information system should meet the essential requirements of both daily and dynamic, and the system can adopt a distributed three-tier architecture, including data layer, business logic layer and presentation layer.
The database server stores a large number of data and data logic, and the consistency and concurrent operation of data and all security and integrity control related to data are completed in the data layer; The business logic layer can be divided into multiple layers as needed to control all applications and application logic. By handling business logic separately, the user interface and application logic can be located on different platforms, that is, when the requirements change, the logic layer can quickly update the business logic on the application server without rewriting the code and submitting the updated application to all clients. They define communication protocols through the system so that business logic can be shared by all users. The presentation layer mainly refers to the user interface, which is as simple as possible and convenient for end users to access and operate.
This three-tier architecture can realize the distributed management of data. By providing a system maintenance toolkit for business personnel, when the system needs to be changed, such as organizational structure adjustment, business process change, table increase or decrease, etc., business personnel can adjust the application system that adapts to the new changes without programming, making the system an adaptive system that meets the requirements of random changes in daily office and management mode and management system.
2 database design and management
The database of e-government information system includes platform support database, land business database and basic space database, in which the platform support database stores definition information related to system maintenance, such as organization, workflow, business form, layer, etc. The land business database stores business information such as approval workflow, approval form and business supervision; The basic spatial database stores geographic information such as approval map, basic topographic map and other thematic maps involved in business processing, and is organized according to the hierarchical structure of "logical layer-physical layer-elements and attributes" to ensure the integrity and consistency of data. As shown in figure 1.
Figure 1 Logical Structure Design of System Database
2. 1 overall design
2. 1. 1 metadata organization
Metadata is a distributed information system composed of various digital resources, which provides tools and ties for integration and is one of the important conditions for data to play its role. Through metadata management, spatial data can be effectively organized, and databases can be efficiently retrieved and accessed, so that computer system resources can be fully utilized to meet the needs of different users for different types of data and operations such as exchange, update, indexing and integration.
2. 1.2 principles of classification and stratification
A class of graphic elements with the same physical meaning and spatial characteristics are stored together to form a physical layer, and a database is established with the physical layer as the basic unit, and then a group of interrelated physical layers are formed into a logical layer to describe a relatively independent and complete data content in the data stream.
2. 1.3 Connection between spatial data and attribute data
Basic spatial data includes basic attributes and extended attributes. The basic attributes are directly stored in the attribute table of graphic data, including classification code, identification code, name, etc. , do not need to be stored separately. Extended attributes mainly refer to business attributes other than basic attributes. Spatial data and attribute data are stored separately and associated by unique identification codes, which is convenient for the operation, management and expansion of spatial data and attribute data.
2. 1.4 distributed management
Through the management of distributed spatial database, users can access spatial information under different databases at the same time, which not only facilitates users to manage different types of spatial data, but also reduces the risks brought by centralized spatial data management and improves the overall application level of the system.
2.2 massive data management
The amount of land and resources data is huge, covering vectors, grids, files and other types of data, and with the development of database construction, the amount of data will increase exponentially. For the management of massive data, we should follow the construction of GIS database, formulate a unified coding standard, and rationally allocate data storage space.
2.2. 1 spatial database standard coding system
Combined with industry coding norms and standards, all geographic information is classified and coded and stored according to certain rules. For the special specifications and standards of each business, learn from the general rules, follow the expert's advice when there are differences in practice, and control the import, export, integration and cutting of data to ensure the consistency, standardization and accuracy of data.
2.2.2 Spatial data service based on Oracle9i +ArcSDE.
As an efficient geographic data server and a dedicated geographic data sharing server, ArcSDE supports centralized and distributed storage and management from basic topographic data to thematic data applied by various business departments. ArcSDE provides support for large-scale and high-resolution raster data, can manage multi-scale, multi-resolution and multi-data source orthographic image data, and can quickly and seamlessly browse from low resolution to high resolution.
2.3 Spatial data configuration operation
2.3. 1 distributed storage
The system stores spatial information according to the three-tier system of "layer details-physical layer-map service", as shown in Figure 2.
Figure 2 Distributed storage of spatial data
Among them, the "system server ID" field in the physical layer table structure is used to indicate the database server where the physical layer is located, and the database server information is stored in the system service table. In this way, the spatial database looks like a whole, but it is not actually stored in the same physical location.
2.3.2 Multi-level management
The system manages layers according to the three-tier system of "thematic grouping-thematic-layer details". Users can define multiple thematic groups, each thematic group can define multiple themes, and each theme can define which layers it contains, as shown in Figure 3.
Figure 3 Multi-level Layer Management System
The complete information of a topic is described by a topic table, a topic layer table, a topic layer list, a topic main physical layer table, a topic sequence list and a topic physical layer sequence table. Each topic contains a data type attribute, which is used to express the format of the contained data, laying a foundation for supporting spatial data operation of multi-GIS platforms.
2.3.3 Spatial data operation authority control
Spatial data operation permissions include layer permissions, map hotspot permissions and fixed range permissions. Layer permissions are divided into edit permissions, browse permissions, query permissions and print permissions.
Spatial data operation permissions are defined as file-related permissions and file-independent permissions. File-related permissions can be set separately or uniformly for different users according to the workflow. For example, in the core layer, only editing permission can be set in the relevant permissions of files, which ensures the security of data. Permissions unrelated to files are defined according to organizations and can be targeted at individuals.
2.4 Temporal management of spatial data
Temporal management of spatial data provides support for historical tracing and historical query of spatial data, and can conveniently query and compare the land status and ownership of any plot in different historical periods.
2.4. 1 Temporal management structure of spatial data
The layer is divided into normal layer, working layer and core layer according to whether temporal management is needed, and the core layer is the layer that needs temporal management. As shown in Figure 4, the physical layer definition table gives the basic attributes of the physical layer, and the physical layer takes out the system fields of the layer from the layer system field table according to the layer attributes. When the core layer is generated, three tables are actually generated: working diagram, current situation diagram and historical diagram. In each table, four fields are defined, that is, date before change, serial number before change, date after change and serial number after change, to identify the tense of spatial data.
2.4.2 Time transmission of spatial data
The time transmission of spatial data can be completed through four fields in the core layer. As shown in Figure 5, when backtracking the history, according to the date and serial number of the last change in the layer records, the records before the change can be found in the historical map in a certain order; According to the change date and serial number in the layer record, you can find the change record in the historical map.
Fig. 4 Time management structure of spatial data
Fig. 5 schematic diagram of time transmission of spatial data
3 commercial applications
To sum up, e-government information system is based on three-tier architecture, which can realize the integrated office of m is, GIS and OA, realize the related application of business and basic data, land change management, law enforcement supervision combining GPS and GIS, land and resources supervision by multi-phase image comparison, flexible statistical analysis of project management results, information exchange between municipal bureau and planning commission, and supervision of various businesses. The system can realize the informationization of the process from receiving parts, data entry, sub-management and leadership approval to inventory and completion, which will greatly improve the work efficiency (Figure 6).
Figure 6 Business Work Flow Chart
4 there is a problem
Due to the initial establishment of information work, there are a series of problems in system construction and application, which are as follows:
4. 1 Information standardization lacks overall coordination and unification.
Informatization construction is still in the primary stage, project-driven, without overall planning. On the whole, information standardization has no unified goal and the coordination mechanism is not perfect. The standard system compiled by various business departments failed to build an overall information standard system according to the characteristics of informatization. For example, if we don't extract information from the process characteristics of informatization and formulate a unified database classification and coding standard, the classification and coding can't be coordinated. In addition, the lack of important standards such as metadata standards and data quality control standards has brought great difficulties to data exchange and sharing, data security and practicality.
4.2 Database construction lags behind
Facing the storage and management of massive data, the database was not designed strictly and carefully before the system development, and the data storage lacked planning and the structure was chaotic. A large number of test data and duplicate data are produced in the later period, which increases the burden on the database server and makes it difficult to update and maintain the data, resulting in low system efficiency.
4.3 Layer query statistics and auxiliary decision-making function is weak.
Because there are many historical files and the measurement results are not uniform, the system lacks the overlapping query function between different layers, which needs further processing to provide methods and means for data analysis and decision-making.
5 Measures and suggestions
5. 1 Strengthen the construction of information standard system
At present, the construction of land and resources informatization standard system is lagging behind, and it should be further improved from the aspects of structure, framework and level, and developed in a systematic and comprehensive direction. It is suggested to carry out research on the standards of land and resources data quality control, digital achievement acceptance and system acceptance composed of professional institutions, and establish a broad and unified standard updating and maintenance mechanism to maintain its long-term stability and uniqueness.
5.2 Strengthen data collation and integration.
The Beijing Municipal Bureau of Land and Resources stores multivariate data with different scales, different projection methods, different data formats and different tenses, and the data standards of all districts and counties are not uniform, so it is difficult to integrate data, which affects the quality and utilization efficiency of the database and hinders the further promotion of informatization. Therefore, we should strengthen the sorting and integration of data, attach importance to the construction of metadata and directory data, and improve the use planning and detailed design of database servers.
5.3 With the help of advanced technology to assist system decision-making.
Data warehouse and data mining technology are helpful to discover the potential relationship between all kinds of data and similar data in history, present situation and future trends, enhance the use value of data, make the system play a guiding role in land use planning, farmland protection, mineral resources development and idle land inventory, increase the decision-making ability of the system, provide a basis for leadership decision-making, realize "clear situation, accurate figures and high efficiency" and give full play to the role of informatization.
6 conclusion
According to the guiding principle of "unified leadership, overall planning, unified standards, * * enjoying resources, service management and serving the society", the e-government information system will closely focus on the planning, management, protection and rational utilization of land and resources, and build a digital land and resources information support base and public information service window integrating management, operation and service.
refer to
Bian Fuling. Geographic information system. Wuhan: Wuhan University Press.
Zhu Dehai, Yan Tailai, et al. Land management information system. Beijing China Agricultural University Press 2000.