WebGIS System Overview
WebGIS system overview, development background
Geographic Information System (GIS) is widely used in various fields of national economy. Especially in the field of traffic management, GIS has a more important position. Modern urban roads are the main part of the overall urban planning, which is related to the organic activities of the entire city. The management of the urban road network, including the maintenance and equipment replacement of road monitoring points, the query of road congestion, the search of the shortest path for routes, and the browsing and spatial retrieval of the city's overall picture, can be intuitively reflected in GIS. Therefore, the development and application of traffic WebGIS information system has high practical value and commercial prospect.
This paper introduces the construction of traffic WebGIS information system based on Web platform. The mobile phone client adopts the APP of ArcGIS online electronic map, the front-end map display editing adopts the ArcG IS development framework, the overall system framework adopts SSH (Struts2 + Spring2 + Hibernate3), the map front-end framework adopts ArcGIS JavaScript Web, and the map server is ArcGIS Server10. 2, The Web server is Tomcat?. 0, ArcGISDesktoplO. 2 is used for map editing and data analysis, and the database is PostgreSQL + PostGIS.
demand analysis
Traffic WebGIS information system is a network information system for the rapid release, query and retrieval of road traffic information and urban spatial information, as well as related statistical analysis. The main user is the road traffic management department, and some functions will be opened to the general public in the future. Therefore, the system interface must be simple and friendly, while providing comprehensive functions. Combined with the actual needs of urban road traffic information management, and followed the principles of scientificity, practicability, scalability and openness, the system should realize the following functions:
(1) Map management function. Realize layered display and management of map layers, realize basic zoom in, zoom out, pan, roam, map query, layer control, eagle eye and other operations; real-time display of road traffic flow information in different colors, so as to analyze the current road Traffic conditions; business information on the map should be synchronized with the map location.
(2) APP function of the mobile terminal. Map browsing, location search, route query, positioning and navigation, etc. Therefore, in terms of interface design, a main interface and three secondary interfaces are used to realize these basic map functions. The main interface displays the basic map, and you can switch between different types of maps through the option menu. The three secondary interfaces respectively realize the location search function, route query function and navigation function.
(3) Multi-granularity evaluation and display of regional traffic status service level. Provide the service level and index display of the classic area division and the service level and index display of any area division, that is, display the service level of each area according to the classic urban division or the classic traffic area division, and users can also perform according to their own needs Any area division, the system will automatically calculate and display the various index parameters and service levels of each area in the area division.
(4) Short-term prediction and forecast of main roads and regional traffic in urban areas. Provides the display of road and regional traffic status after 5 minutes, 10 minutes, and 15 minutes, as well as statistical analysis and comparison with the current status.
(5) Path planning. Display an optimal route according to any stop points added on the map, and at the same time, add temporary event obstacle points on this route, regenerate and display a new route.
(6) Navigation function. According to different input destinations (or two different input locations), an optimal route will be displayed on the map, and multiple intermediate points can be added in the list box to generate an optimal route passing through different intermediate points at the same time.
(7) User management and authority control. User management is mainly to add, delete and modify user information. User rights control is mainly to set different rights for different users’ requests. Users at the system administrator level can use the system configuration and editing functions to update and modify the system parameters and data of the server. Ordinary users may only With browsing, query, statistical drawing and other functions.
(8) Other functions, such as system management, announcement management, log management, etc. In addition to the above main functions, the traffic WebGIS information system should also meet the following non-functional requirements:
(1) System performance: ensure that the source of system data is reliable and real-time, and the response time to information query should not exceed 5 seconds.
(2) System openness: the system is required to be compatible with different geographic information systems and geographic information data in different formats; the functions provided by the system should be able to support operating systems in different languages.
(3) System portability: The whole system should have high reliability and stability to meet the requirements of continuous and stable operation.
(4) Data management performance: The system should meet the capacity management requirements for data stored within the current two years; support the management requirements for data growth within three years.
(5) Data collection frequency: In order to ensure that the regional traffic information system can accurately monitor the service level status, and taking into account the special circumstances during peak hours, the data collection frequency of the detector should be sent once every two minutes.
overall system design
The overall architecture design of the system is the key to project development. The quality of the overall design will be related to whether the system development process is smooth and whether it is convenient to maintain in the future. The system is built on the basis of the Web platform. The mobile client uses the ArcGIS online electronic map APP. The front-end map display and editing adopts the ArcGIS development framework. The overall system framework adopts SSH (Struts2 + Spring2 + Hibernate3). ArcGIS ServerlO. 2, the Web server is Tomcat7. 0, ArcGIS DesktoplO. 2 is used for map editing and data analysis, and the database is PostgreSQL + PostGIS. The first is the logical layered design of the traffic WebGIS information system, which fully follows the MVC modular design, logical layered
Among them, the view layer is also called the "presentation layer", which is the window for the system to interact with the user. All the pages seen by the user can be called the window layer, which is realized through Struts2 and JSP. The control layer accepts user requests from the window layer, and then fetches the processing results from the model layer and returns them to the window layer, which does not involve any specific business logic processing.
The model layer is responsible for processing the business logic and the underlying operations of the database. In order to continue to reduce the relationship between programs, this layer is divided into a business layer and a persistence layer in the project design. The former is responsible for the processing of business logic; the latter is responsible for the underlying operations of the database. , completely separate the persistence operation from the business, and improve the modular design of the program. The internal relationship between logical layers is shown in the figure
