Research On The Key Technology Of Web Collaboration Oriented On Spatial Information

Since the first geographic information system has been developed in Canada in 1960s, the geographic information system platform and application system has made remarkable development along with the development of computer technology in the past 50 years. Now it has been increasingly applied to in environmental assessment, resource surveys, public services, GPS navigation, disaster prediction, land management, urban planning, communications, transportation, water conservancy, electric power, agriculture, forestry, animal husbandry, statistics and commercial finance and other fields.In recent years, with the development of Internet technology and information systems, users want to share the spatial data and processing functions distributed in different regions and different departments. This spatial data sharing and interoperability makes the spatial information services are no longer confined to professional users, but to common users to access and use easily. Currently, many departments have developed geographic information application systems according to their business needs based on the spatial data sharement, and these systems have played a significant role during practical work. However, with the deeply application, there are also many problems. These problems are mainly reflected in the following aspects:1) WebGIS's limited synergyWebGIS technology is focused on the release and display of maps, and considers less in the manipulation methods and functions. So it usually only provides simple query functions or a small amount of spatial data operations, but cannot implement complex spatial information operations, as well as to meet the interoperability requirements in distributed environment.2) Insufficient cooperation degree between spatial information and businessSpatial applications systems are relatively independent each other. There lacks good share ability and interoperability among these spatial systems because that different spatial application systems use different platform to establish and maintain spatial data. The different spatial data model and different demands for spatial data will both impact on the interoperability in deep level. The current application systems have a high coupling degree, considering less to the integration and interoperability to third party systems, so that it is difficult to combine different systems to get a unified service for more applications.3) The inadequate capacity of Geographic Information Services combination As the network and application systems change dynamically, the geographical information services based on them also change dynamically. So in practice we often use dynamic aggregation of spatial information operations in order to adapt to system expansion. Therefore, an effective combination of spatial information resources of space applications is important to spatial information application.4) Lack of workflow engine to support spatial informationGeographic information systems have abundant spatial data and attribute information, as well as abundant spatial operations and spatial analysis capabilities. However, they lack of good sharing mechanism, as well as effective mechanisms on modeling and managing complex information processing process. The workflow technology has a clear advantage in these areas, so it's very important to introduce workflow technology into spatial information systems to model and manage workflow in spatial information system.5) Inadequate security consideration in spatial collaborative information systemsNow geographic information systems consider less on security in distributed collaborative environment, mainly including authentication, access control and other problems.6) Lack of a flexible spatial applications frameworkThe development of spatial information systems are mostly for special application environments, and there lack a basic framework to satisfy most spatial systems. This results on difficulty to implement business end in real time to adapt to the varied business process.In the support of Web Service and OpenGIS specifications, the architecture and application model of spatial information system is facing new opportunities and challenges. It requires that systems change from traditional data high-coupling, centralized, closed modes to data loose-coupled, distributed, and open modes. So it becomes the primary task to manage spatial data sharement, establish collaborative mechanism, and achieve a unified service model for spatial information so as to build spatial application systems quickly based on these new theories and methods.This paper -- "Research on spatial information-oriented Web collaborative workflow" is a sub task to "large-scale distributed GIS" standing on fruits of the national 863 project-"network-oriented large-scale spatial information GIS". Its main purpose is to establish a unified spatial information workflow service together with collaboration technology between spatial information service and workflow, as well as to provide an integrated application infrastructure framework for spatial information application system to provide tools for rapid development. So that it can give an effective solution to the problems emerging from the current WebGIS applications.Specific studies are as follows:1) Study deeply on spatial data sharing model, analysis the architecture of current spatial information services, put forward a spatial information service model based on data-centralized model, then discuss and describe its four-layer architecture concretely. 2) Integrate spatial information and workflow technology, then put forward a spatial information workflow model and analysis the definition, description and specification of spatial information service under data-centralized model.3) Discuss the access control based on role and workflow, put forward authority management methods based on ontology, describe authentication methods, security model structure, as well as authority computation algorithm based on ontology, and gives an example finally. This algorithm can not only describe the complex secure access policies of spatial information, but also be able to handle access control constraints, thereby enhancing the system's security and strengthen spatial information security control intelligence in GIS.4) Discuss business rules of the workflow engine, with a focus on the workflow instance concurrency issues under multi-agent and multi-instance, and then put forward the relevant algorithms. On this basis, describe the highly intelligent work process with spatial information workflow, and then give the algorithm description and case analysis.5) Users can use the spatial information services through Web so as to implement multi-level and multi-way collaboration. This paper establishes a web collaborative application framework, and discusses the expansion approach of the framework. Subsequently, introduce how to build a system under this framework, and then gives related model of spatial information business end. During the spatial information systems'development process, building business end quickly with spatial service-oriented form method can avoid duplication of development and accelerate the system construction.6) Discuss the table structure implemented by workflow model, and then give a prototype framework, describe rights management-related functions, finally introduce the implementation details about custom forms. Forms based on spatial information services can build business end quickly by combining with spatial information workflow. This technology can avoid duplication of development and accelerate the system construction. The model has been successfully applied in MAPGIS in practice and achieves good results.This paper introduces workflow technology into the spatial information field, research's on how to improve spatial information service combined with workflow technology, so that it can solve a series problems such as difficulty in sharing, service combination complexly, less consideration in security, less degree in cooperation and complex development. We deeply research the key technology of Web collaboration of spatial information service, and introduce the workflow technology, business end establishment and ontology into intelligent spatial information service. The main innovation is reflected in the following areas:1) Combine spatial information services and data-centralized mode gracefully, put forward the concept of collaborative spatial information services; present the integration method and architecture of spatial information service under data-centralized mode, together with analyzing the composition and characteristics of this architecture, so as to make a useful exploration of integrating GIS based on spatial information services. 2) Discuss the workflow technology deeply since it's the basis of collaborative spatial information services, study the interactive method of workflow with spatial information services, point to the definition and service primitive of spatial information workflow, as well as the interface definition of common GIS function services, discuss service granularity, establish a spatial information workflow engine, describe its algorithm relatively, and make foundation to collaborative spatial information service.3) Introduce ontology-based method into the collaborative environment to manage system license, put forward the spatial information authorization mechanism based on ontology, and then give the implementation model.4) Discuss the related integration issues about spatial information services and business model and design a method to establish spatial information business end quickly. On the base of this, put forward a service-oriented business model and implement the quick establishment of GIS Web business end under some special environment.5) Point out that the spatial information services collaboration is a systematic project, discuss how to introduce Web technology into the spatial information service applications, study the architecture of Web-based collaborative spatial information services, arid then put forward the corresponding platform framework so as to implement a web collaboration system prototype.