Research on J2EE-based mobile positioning service

Abstract: This paper introduces the architecture of mobile location service (MLS) based on J2EE, and introduces the GIS application server and information equipment suitable for MLS.
The key technology of map visualization expression is given. Two solutions of geosurf WAP and j2's are given, and their application prospects are described.
Key words: Mobile Positioning Service; GIS application server; Information Equipment
Graph classification: P208
Currently
More and more functions are available. The earliest Web GIS developed by ESRI
Product Mo IMS and ArcView IMS are gradually upgraded
Arcims3. 0. ArcIMS is a production task running in the javatm2 environment.
Product, including Application Server Connector, application server, and space
The data processing server and the customer have four major components. MapInfo public
The company's Web GIS products are proserver and mapxtreme.
In 2000, JavaBean-based GIS middleware product was launched.
Mapxtreme for Java 3.0, including mapxtremeservlet plotting
Engine, mapj function object, mapxtreme JavaBeans component,
Map definition manager and Connection Manager. In
Based on mapxtreme, a java servlet-based
Path server jrouteserver and mobile positioning service software
Miaware allows mobile phones, PDAs, and other information devices to pass through
Line Network, providing personal registration information anytime and anywhere
Information Server of the wireless space related to the current or pre-location
Service.
J2EE has become the preferred platform for large-scale distributed applications,
Industries such as telecommunications and finance have adopted J2EE as the Middleware
Improve system availability, reliability, and cross-platform
. The existing large and high-end server hardware market is basically
IBM, sun, and HP are monopolized. They all use Unix systems
A middleware infrastructure platform compliant with J2EE standards is available. However,
Because the implementation of J2EE requires at least component developers and Applications Program
6 different types of assemblies, deployers, servers, and container providers
Role, the development has invested a lot in the early stage, therefore, based on the J2EE
There is not much research on the mobile positioning service.
Positioning Service Technology
Different forms of development are presented. In summary, I have gone through the following
Three stages of development: centralized standalone positioning and web-based Customization
Location Based on Wireless information. The mobile positioning service is
Provides personal registration-based services anytime, anywhere
Information and the current or pre-location enhancement wireless space service.
The mobile positioning service is based on wireless networks, around the clock, paid mail
Information Service, extensive Device Support, real-time interaction, and other features. However,
Due to the unpredictability of users in the wireless network environment
Point, number of users, user clicks), network connection instability
(Network congestion, narrowband network, connection-oriented network), spatial data
Mobile Positioning server is required because of its massive capacity and accuracy of location information.
Provides cross-platform, high reliability and high availability. Use J2EE
To meet the above requirements
Step by step.
1. J2EE-based MLS Architecture
The J2EE-based MLS adopts the J2EE standard to construct the base
A mobile positioning service system with a multi-layer architecture. 1
Information Equipment, Gateway agent software, GIS Application Server
Server and data server. Information device inclusion
WAP mobile terminal, j2-mobile terminal, PDA mobile terminal and
Four types of palm terminals. Location in GIS Application Server
Service business logic mainly includes geographical encoding, visualization, and spatial score
Analysis, path and address search, geographic-based statistics, and other services. Quantity
The database server contains the spatial database, location information database,
Poi database and POA database. General storage of spatial databases
Terrain data, such as digital line chart, digital grid map, and digital location
Surface Model data, which may include residential areas, water systems, roads, and areas
The location information database records the current information device.

The image of this topic is as follows:

Location information, usually by the Telecommunications Department or location service provider
Maintenance; poi database is a point of interest database, which is specialized data
Library, in addition to providing space information, usually also provide the name, contact
Type, location, level, and other attributes; POA database is of interest
The content of the regional database is consistent with that of the poi database.
2. J2EE-based MLS business logic
Key Technologies
2. 1. GIS application server in MLS
The GIS application server is mainly used to complete the key business in the drawing service.
Processing of Service Logic, such as coordinate transformation, Geographic Encoding, and address matching
Time-consuming GIS processing. Generally, the GIS application server in MLS
The server must be able to complete maps, features, place names, yellow pages, ground layer,
News, traffic conditions, and optimal routes. Figure 2 is Based on JSP,
The structure of the servlet and xml gis application server, where
Geoxml is a JSP application running on a Web server,
It is also the RMI client of the GIS application server. System Access
It deals with clients and accepts and transfers requests
GIS application server for processing, return results to information settings
Backup. When geoxml accepts a call request from a client,
It accepts the connection between the client and the server.
Georequestdom (including the parameter name transmitted by the client
The protocol used by the user to generate a request and accept the request
The remote host name of the server, the requested operation type), and
Some requests call
RMI server, start the corresponding parts to complete the task, and pass the result
Instantiate georeponsedom for geoxml and return the information
Device. GIS Application Server is a servlet-based application.
Service engine, which calls the JavaBean Component to complete the map
The current extension, by calling the gis ejb component from the remote space
The data warehouse completes map data acquisition and other business logic.

The image of this topic is as follows:

2. 2 Information Equipment Space Information Visualization Technology
According to the definition of OGC Internet map interface Implementation specification,
Internet-based spatial information visualization includes query, generation,
Expand and display the four most basic processes. Query is also called
Filtering refers to obtaining from raw data that meets the client query Conditions
Is called the generation of display series, that is, the query
The resulting data set is combined to generate a sequence of display elements;
Expansion, also known as forming, is about to display the final needs of the generation of element Series
Display the map result, and finally send the prepared map to display
The device is displayed. Visualization of the mobile positioning service map
In the aspect of visualization, the author uses a vector map for progressive transmission display and location
Two remote graph extension methods are available.
2. 2. 1. Progressive Transmission and display of vector maps
In traditional GIS,
Surface, annotation, symbol, shadow, color, and coordinate system to express Space
Data. In the terrain data, the coordinate system is used
The real world is organically linked, at most basic levels only
Is to simply add the geographic coordinate system to the visualized processing stream
. In a wireless distributed network environment
Width cannot download all the data to the customer at one time.
Therefore, the vector map data adopts the progressive transmission mode.
File stream and object stream. File stream mode on the server
When the configuration is low and the client configuration is high
Advantage: the client speed is relatively slow; the object stream mode is configured on the server
The advantage is obvious when it is relatively high, and the display speed of the client is
Fast. Whether it is file stream or object stream transmission
Data Cache Management and data cache are required on both the user and server.
The main task of management is to complete the number of servers and clients
Data scheduling ensures data consistency, integrity, and speed.
. The data display process is as follows.
1) according to the current display area range
{[Screenstartx, screenstarty], [screenendx,
Screenendy]} and current scale and actual library coordinate range
{[Realstartx, realstarty], [realendx, realendy]}, initial
Dual-buffer zone for the entire drawing area.
2) Obtain a visual location on the client based on the current scale
Object encoding, and then according to the current visual object class encoding and Screen Display
Shows the range of the region to obtain the corresponding OID set from the database.
3) Based on the Cache Management of the server OID set, obtain
To the oId set where space data needs to be retrieved again.
4) obtain the amount of space from the database based on the new OID set
Data recording, interpretation, and objectization.
5) it is transmitted to the client over the network for display.
2. 2. local and remote extended Display Technology of Map Symbols
After adding symbols to a vector map, the graphic table will be greatly added.
Achieve results. The map on the information device is symbolic and must be tested.
The amount of data transmitted over the wireless network. One direct approach is not
Use any image to fit the filtered device coordinates.
Symbolic processing (Zhang fuhao, 2001). This method can be called local
The image is scaled locally. It is suitable for broadband wireless networks.
PDA mobile phone. Another method is remote map expansion.
Display, that is, the display and graphic extensions are completed on different machines in the server
Run the Map Symbol local extension function on the server, and then generate
A raster map in a specific format is transmitted to the client for display.
This method is suitable for mobile phones of the WAP and j2_type in narrowband network environments.
For example, in the geosurf image service, geosurf imagerenderer
You can refer to a geosurfservlet instance from a URL.
Created when geosurfview uses a geosurf imagerenderer
It means to get the grid from a geosurfservlet instance
Map, geosurfservlet returns a raster image to the customer
The client responds to this request.
3 instances
In the experiment, geosurfv4. 0 is used as the server.
GIS application middleware platform, using tomcat4. 0. 3
Basic Application Server Platform, using Oracle8i as the database
Platform, constructed a J2EE-based MLS system, which is applied in GIS
Based on the middleware platform, the map performance and request response are extended.
Module. This article uses JSP technology to obtain the WAP terminal and
The XML requests of the j2s terminal separate these XML requests.
Class is processed by the business logic engine, and then packaged and released in XML
To the client. For WAP terminals, 3 shows that the system
The format of the sent map is wbmp.
The format of the sent map is PNG and vector data.

The image of this topic is as follows:

J2EE-based MLS can be managed in Customer Relationship
(CRM), enterprise resource planning (ERP) and Logistics Supply Chain
It has broad application prospects.
4 knots
This article analyzes the concepts, features, and body of the mobile positioning service.
Based on the system structure, a mobile positioning server based on J2EE is proposed.
Service implementation system framework, several key technologies, and two types of mobile terminal
End-type map implementation instance. From positioning the market prospects of services,
In terms of technical background, service content, and application prospects
Has a broad future for development. However, the wireless positioning service requires
To penetrate into various industries, we must solve the problems of wireless network broadband transmission and sea
Volume Space Data Management, multi-user concurrent access to space data and
Intelligent Geographic Information Service in the network environment. With technology
Technology and service development, wireless location service will be
A new hotspot.
Thank you: Wuhan University, China
Help and Support from the network GIS team members of key laboratories.
Contribution
1. Li deren, Li Qingquan, Xie Zhiying, et al.
The integrated application of. Journal of Wuhan University · Information Science Edition, 2002, 27 (1 ):
1 ~ 8
2. Li deren and Li Qingquan
Integration. Journal of Wuhan University-Information Science, 2001, 26 (1): 1 ~ 7
3 Doyle a, Reed C. Introduction to OGC Web Services.
HTTP: ppwww. OpenGIS. org, 2001
4 Chen B, Fang Y. Technology and Development of massive
Distribute Geographic Information System. Journal of Image
And graphics, 2001, 6 (9): 861 ~ 864
5 sonnen D, Morris H. Location in CRM: Linking virtual
Information to the real world. http: ppwww. idc. com, 2000
6 Giguere E. Using the MIDP choice group component.
HTTP: ppwireless. java. Sun. compmidppttipspchoicegroup, 2002
7 Giguere E. Wireless messaging API basics. http: ppwireless.
Java. Sun. Comp mid ppttipspwma, 2002
8 Giguere E. Understanding J2EE application models. http: pp
Wireless. java. Sun. compmidpparticipant lespmodels, 2002
9 Knudsen J. MIDP application security 1: Design concerns
And cryphtography. http: ppwireless. java. Sun. compmidpp
Articlespsecurity1, 2002
10 Mahmoud Q. MIDP network programming using HTTP and
The connection framework. http: ppwireless. java. Sun. Comp
Midpp article network, 2002