STUDY ON THE STANDARD ARCHITECTURE FOR GEOINFORMATION COMMON SERVICES

The construction of platform for geoinformation common services was completed or on going in in most provinces and cities in these years in China, and the platforms plays an important role in the economic and social activities . Geoinfromation and geoinfromation based services are the key issues in the platform .The standards on geoinormation common services play as bridges among the users, systems and designers of the platform. The standard architecture for geoinformation common services is the guideline for designing and using the standard system in which the standards integrated to each other to promote the development, sharing and services of geoinformation resources. To establish the standard architecture for geoinformation common services is one of the tasks of ‘Study on important standards for geonformation common services and management of public facilities in city’. The scope of the standard architecture is defined, such as data or information model, interoperability interface or service, information management. Some Research work on the status of international standards of geoinormation common services in organization and countries, like ISO/TC 211, OGC and other countries or unions like USA、EU、Japan have done. Some principles are set up to evaluate the standard, such as availability, suitability and extensible ability. Then the development requirement and practical situation are analyzed, and a framework of the standard architecture for geoinformation common services are proposed. Finally, a summary and prospects of the geoinformation standards are made.


INTRODUCTION 1.1 National Platform for Common Geospatial Information Services
The National Platform for Common GeoSpatial Information Services, which is also known as TIANDITU, is the website providing "one-stop" geospatial information services to personal users, enterprises, professional agencies and governments via networks such as Internet, mobile communication network, Intranet, etc.It is created by National Administration of Surveying, Mapping and Geoinformation of China (NASG) as an important part of the geospatial framework for digital China aims at promoting the geographic information resources sharing, and improving the ability and efficiency for services.Website users can browse maps, locate places, measure distances or areas, plan car driving routes, while professional users can access various TIANDITU's service resources via standardized interfaces for value-added services and applications.TIANDITU also provides many Application Programming Interfaces (APIs) to facilitate the integration of its service resources and various systems or websites.With these standardized interfaces and APIs the users can avoid the chaos for handling, maintenance and updating the base maps and focus on their own thematic data and applications.Thus decrease the development and research cost for providing commercial or professional applications.

Standard and Standard Architecture
The construction of TIANDITU was completed or on going in in most provinces and municipalities in these years, the platforms plays an important role in the economic and social activities .Geoinfromation and geoinfromation based services are the key issues in the platform .The standards on geoinormation common services play as bridges among the users, systems and designers of the platform.The standard architecture for geoinformation common services is the guideline for designing and using the standard system in which the standards integrated to each other to promote the development, sharing and services of geoinformation resources.

International Development
The development of international standards geographic information industry is growing very rapidly, every country takes the standards very seriously, and takes close cooperation in the research of geographic information standardization and creating standards.International standardization of geographical information can be roughly divided into two parts.One is taking the existing information technology (IT) standards, directly or indirectly using the other is the development of geographic information-oriented features of the standard, including data definitions, data description, data processing and other aspects of shared services .Like other standards, geographic information standards are divided into five levels, namely international standards, regional standards, national standards, local standards and other standards(Figure 1).Other international standardization on geographic information : International Hydrographic Organization (IHO) have published the S52, DX90 (S-57) , S60 and other standards, they describes the digital hydrographic data generation, expression, and quality evaluation criteria in detail.The Technical Committee under International Cartographic Association (ICA) is also actively involved in Geographic Information Standards.

Local Development in
Geographic information and geographic information common services has been widely used in the national economy, security and public life, and gradually formed geographic information services industry by the geographic information common service including elements of geographic information, services and platform.Standardization of geographic information common services in China has achieved great development.
There are four levels of standards in China: national standards, industry standards, local standards and enterprise standards(Figure 1).National geographic information common service platform has also been launched during the 11 th Five-Year,.Meanwhile, some new trends of standardization work began, for example: the standardization is converting from GIS data to geographic information service.
"The 12th Five-year Plan of Surveying, Mapping and Geoinformation Standardization" made it clear that to fulfil the zero breakthrough from national standard to international standard.On March 2012, "Geographic information --Content components and encoding rules for imagery and gridded data" (ISO/WD TR19163)was proposed to ISO/TC211, and now it is under development on Working Draft.
Based on the classification of attributes, spatial types and senser types, the standard describes the needed content components for imagery and grided data, define data structure and encoding rules for mapping the content to the data structure.The project implementation time is from Nov.7 2012 to Nov. 7, 2015.

scope
Geoinformation common services standard system consists of the standards which support universal development and application service in geoinformation fields.The feature of the standard system to geoinformation standards is to support geoinformation common services platform applications, and focus on geographic information data resources, service ability, application and construction for the common services platform.

methodology
ISO / TC 211 used concepts and methods of software engineering, take the Unified Modeling Language (Unified Modeling Language, UML) as its standard conceptual schema language, to plan and build international standard reference model and a series of geographic information standards, and achieved good results.In China, the hierarchical chart and sequence chart are commonly used method to build a standard system architecture, it can make classification and grading with their own level, grade, types, function, profession and other properties, or , it can be devided by the standardized object life cycle, so it becomes a general process for building standards system tables.So, this standard system architecture were made under the guiding of system engineering theory, used UML static chart to express the architecture and inherent logical relationship of geoinformation common services.Geoinformation common services is a complete procedure of information system integration and applying consisting of geoinformation data, services, construction and application, it has a positive effect for clearing internal information flow by using UML to build the standard system architecture.
The architecture result show in Figure 2.

Basic Standard
Base standard provides technology framework for geoinformation common services standardization, it gives the reference standard collection when develop related standards, includeing 4 subclass: reference models, terminology, reference system and schema framework.

Data Resources
This class takes account the content, access, representation, maintenance of geoinformation common services, and gives the definition standard for data content, classification and representation.

Mangement
This class provides system model for building geoinformation common services management, it gives the subclass about construction requirements, management specification , design and construction specification of application system and the platform.

Developing Suggestion
The data resources standard(200) involve multiple types of data resources, including geographic entity data , places and address data , the electronic map data , image data, elevation data, volunteers geographic data, street view data and so on.Data classification, collection , production, publishing and other aspects of the process required the relevant standards.Geoinformation common services, just like GIS, has the features like multi-technology crossing, multi-industry fields,etc.Therefore, to promote the construction of geoinformation common services platform and implementation of geoinformation common services, we need use the standardization theory as the guideline, innovate existing management and working mechanism of standardization, emphasis enterprise position in development of standard, promote the integration of standardization work among different industry, and multi-technology integration.
Figure 2 Architecture of geoinforamtion common services standards 3.3 Components of the standard architecture Under the provisions of "People's Republic of China Standardization Law": Industry standards are approved by the ministry department and the Commission (Council) within the scope of the department consistent use.For example: machinery, electronics, construction, chemical industry, metallurgy, light industry, textile, transportation, energy, agriculture, forestry, water conservancy, etc., all have developed their own industry standard.
Specification of Electronic Map on Mobile" , related on the foundation of geoinformation common services, or actually developing in industry, should listed as the first class standards.Part of Service standards are mature and widely used in industry, they are usually OGC standards or ISO standards.Although many OGC standards have widely used in fact, such as WFS, WPS, WMTS services, but the process converting to Chinese national standards is still slow, need continue to advance.Such standards, like "Geographic Information: Web Feature Service"," Geographic Information: Web Coverage Service", "Geographic information -Simple Feature Access, refer to ISO 19142, OGC WCS, ISO 19125, which has been tested in industry, the main work is standard adoption.Tile map service can refer OGC WMTS service standard, which was released version 1.0.0 in 2010, has made widely used at home and abroad, the national, provincial and municipal TIANDITU nodes widely used WMTS standard as the standardized map tile service.These standards should be the first class standards.This article relies on the"Important Standard Research for Urban Geographic Information Common Services and Municipal Facilities Management" project which is belong to Public Welfare Scientific Research Project of General Administration of Quality Supervision, Inspection and Quarantine of the R.P.C.(GAQSIQPRC), under the objective for development and use of geographic information common service, propose geographic information common services standard architecture and proposal for development.