DSSE overview |
When the general GIS services cannot satisfy specific needs of a certain industry, the GIS service platform needs to provide a flexible mechanism for extending the services. Developers can incorporate these specific function requirements into the GIS service platform by using this extension mechanism, to provide the industry with a service system for processing spatial information.
Currently, there are a number of approaches to extending GIS services in the GIS platform. Each approach has its own advantages and disadvantages, and is suitable under certain situations.
| Type | Description | Advantages | Disadvantages |
| Fixed extension interface | Custom interfaces are provided in a service, based on which developers can implement specifics of special functions. If the CustomInvoke interface is opened in a service, developers can implement special custom functions by overloading the CustomInvoke() method. | Easy development. It is only needed to implement method overloading. | The interface is not transparent. The interface user and provider need to agree on the format of passed parameters and output result beforehand. Furthermore, a fixed interface can only provide the special functions of one single service, thus is not suitable for customization for complicated business. |
| Building function modules | Implements a set of workflow-based GIS services through building function modules. The GIS service platform provides a mechanism for building models. Developers can build models for GIS function modules, in order to realize GIS services that have certain workflow for processing business. | The modeling is simple and easy to use. | It can build models for existing function modules, but cannot create or integrate extensions for new business. |
| The mechanism for extending domain spatial information services | This extension mechanism provides flexible and easy-to-extend framework for developing service components. In this framework, developers can quickly develop domain spatial information services with characteristics suitable for various domains using the basic GIS modules provided in SuperMap iServer. Domain spatial information services can be integrated to the SuperMap iServer service system using simple and flexible configuration tools. People who need services can then obtain more professional spatial service. |
Flexible and easy to extend. |
SuperMap iServer categorizes spatial services into two types. One is general spatial services (GSS) provided by SuperMap iServer itself, including 3D, etc. The other type is domain spatial information services (DSS) which users build by themselves for processing spatial information based on special business logics of their domains, such as a map service for wind direction symbols applied in the meteorology industry. Although users need to develop the services themselves, SuperMap iServer provides a flexible and agile framework for developing service components as well as a mechanism for operating service components. When developing service components, users can incorporate their business logics with the built-in GIS service modules, and easily integrate their DSS in the service framework in SuperMap iServer.
Basic map services, spatial analysis services, realspace services, and data services provided in SuperMap iServer cover most of the spatial processing functions. But spatial information service alone may not satisfy business requirements of an industry. It may be needed to incorporate the business features or existing business data of an industry into spatial information processing, in order to build a set of spatial information services proper for the specific business logics of this industry. To achieve this, custom business service components can be built with the domain spatial information service mode provided in SuperMap iServer. Then the services can be published by using the domain spatial information service extension mechanism of SuperMap iServer.
Business rules in different industries can be different. Some businesses have logics requirements on spatial information processing that built-in GIS processing modules in SuperMap iServer cannot realize. Therefore users can build custom domain spatial information services that incorporate business logic relationships in their industry to process spatial information. To achieve this, users can employ the GIS processing modules in SuperMap iServer. For example, a stochastic hydrological modeling analysis service can be built for the water conservancy industry. The built-in GIS analysis functions in SuperMap iServer cannot implement the algorithms for stochastic hydrological modeling, whereas the hydrological analyses in the water conservancy industry do not consider the characteristics of spatial variability. Therefore, users can integrate the stochastic hydrological modeling algorithms in the industry and the spatial information processing functions in GIS, to build a spatial information-oriented stochastic hydrological modeling analysis service for the water conservancy industry. This service can be used to analyze drought characteristics and stochastic variability of storm and flood processes in a watershed, to design retention systems, and to support decision making on planning a hydrological and water resource system.
Usually every interaction between a client and a SuperMap iServer spatial service is based on a single GIS function request, such as finding the query result and map location corresponding to a keyword. If a business request needs a combination of two or more GIS functions to obtain a result, the user can combine multiple GIS functions through building a domain spatial information service. This type of domain spatial information services only requires the user to arrange a set of GIS functions. The specific GIS operations can be implemented using the service provider modules in the SuperMap iServer framework.
For businesses that have built information platforms, integrating GIS technology's capacity to process spatial information can certainly help with decision making and information management in the businesses. Users can build domain spatial information services that integrate the original business systems, information management, and decision systems, by using the extension mechanism of SuperMap iServer spatial information services. Interfaces that can be interacted with the original systems can be published in the domain spatial information services. In this way, the original business data can be effectively presented with GIS functions, and the information representation as well as business decision making and management can be fully supported. Domain spatial information services in SuperMap iServer provide some special industries with excellent solutions to the integration between business and spatial information.
The framework of a service system in SuperMap iServer is composed of layers and modules. Services are configured and deployed in a unified fashion. A service framework in SuperMap iServer has three layers. Each layer contains relatively independent function modules in which specific operation contents are implemented. Users can build function modules that conform to the business logics of their industries on any level of the framework, or develop domain spatial information service components by extending a module on a layer. The modules on the layers of services published by SuperMap iServer are organized by the service configuration and management component. Users can deploy their custom DSSs to the SuperMap iServer service system using the service configuration and management component. By doing this, the DSSs are published.
As mentioned above, relatively independent function modules are built in each level of the SuperMap iServer service framework. For example, the basic map service provider module--UGCMapProvider, the 3D service provider module--3DProvider, the RESTful interface module--REST Servlet, etc. These modules communicate with other modules via interfaces. When designing and developing a DSS, the user can implement the GIS processing part by using built-in GIS service modules in SuperMap iServer, and then combine GIS and the business logics of the industry. The built-in GIS service modules in SuperMap iServer are tools for a user to implement the GIS part of a DSS, so that the user can quickly develop a spatial-oriented domain service component.
The extension mechanism of domain spatial information services in SuperMap iServer provider users with a flexible construction mechanism for industry application-based spatial operations. All the modules in the framework of a SuperMap iServer service system are organized and published with the service configuration and management component, which operates by reading the service assembly information and module metadata. This kind of configuration mechanism makes it possible for users to freely combine function modules from the layers. To integrate a custom DSS to a SuperMap iServer system and publish the DSS, the user only needs to describe the metadata of the DSS, and describe its modules and its relationships between the modules on each layer.