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ISPRS WG II/3 Chongjun YANG cjyang@digitalearth.cn Sept. 15-19th 2003, Thailand Co-Chair of ISPRS WG II/3 IRSA/Chinese Academy of Sciences. ISPRS Working Group II/3 Integrated Systems for Spatial Data Management http://www.digitalearth.cn /wgII-3.
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ISPRS WG II/3 Chongjun YANG cjyang@digitalearth.cn Sept. 15-19th 2003, Thailand Co-Chair of ISPRS WG II/3 IRSA/Chinese Academy of Sciences
ISPRS Working Group II/3 Integrated Systems for Spatial Data Management http://www.digitalearth.cn/wgII-3 • WG II/3 Terms of References and Activities • Systems for integrating geo-spatial data • Integrated services involving economic, technical and political aspects • Geo-spatial information distribution and accessibility systems using internet • Development and validation of end-to end spatial data access systems • Liaison with CEOS WGISS and other relevant organizations
Interoperability of Spatial Data Service Chongjun YANG cjyang@digitalearth.net.cn Sept. 15-19th 2003, Thailand Co-Chair of ISPRS WG II/3 IRSA/Chinese Academy of Sciences
Interoperability of Spatial Data Service For Open System
Interoperability of Spatial Data Service • Context • Components of Interoperability • Levels of Interoperability • Criteria for Interoperable System • XML,GML,WMT,C#, .NET • Example • 7. Discussion & Cooperation
1. Context : GIS Computing Computing-Structured(Standlone System) Computing-Centred(Centre- System) Client-Server System(Local Network) Computing-Distributed System(Intranet/Internet)
1. Context Decision Knowledge Se rvice Information Data
1. Context : Trends Data Service GI IT mainstream
Context : Interoperable Mechanism of Internet • Internet : TCP/IP • Web: HTML(XML) • HTTP • API • URI • Little interoperability for spatial data
1.Context :Benefits of interoperable spatial data service (1) eliminating spatial data duplication. (2) reducing the effort required to manage and maintain spatial data. (3) facilitating application development activities. (4) providing a flexible computing environment with access to computing resources ranging from desktop machines to high-performance computers (supercomputers); and (5) reducing costs associated with data acquisition, management, maintenance, and conversion, model development, and overall operations.
2. Components of Interoperability - How should the exchanged data be represented? (data representation) - How should two systems communicate? (application communication protocol) - How should data be addressed across systems? (naming mechanism) - Which functionality should be available between systems? (application programming interface).
3. Levels of Spatial Data Service Interoperability The more the interoperability mechanism “knows” about the spatial data, the advanced the degree of interoperability is.
3. Levels of Spatial Data Service Interoperability 1) DATA KNOWLEDGE From simple to advanced interoperability: • No knowledge about spatial data • knowledge of the structural (syntactic) aspects of the data • knowledge of the schematic aspect of the data • knowledge of the semantic data aspect
3. Levels of Spatial Data Service Interoperability 2) scope of the data model 3) Name Space Management 4) Capabilities of Server API
4. Criteriafor Interoperable System (1) Decisive interoperability criteria, (2) Technology criteria, and (3) Implementation and software criteria.
(1) Decisive Interoperability Criteria • Common data representation: • Which data types are supported? • level of data representation? • is it public? • is it a standard?
(1) Decisive Interoperability Criteria • Server interface: • which functionality is supported? • is it extensible? Is it flexible? • is it public? • is it a standard?
(2) Relevant Technology Criteria • Java • COM/OLE • CORBA/J2EE • GRID • …
(3) Relevant Implementation and Software Product Criteria Format-to-common format conversion via the data server: - Availability of software products (is a complete, stable system available?) - Diverse platform support (is the product available for most platforms?) - Software maturity - Support and Maintenance - Cost of software - Ease of hosting data via the system
5. XML,GML,WMT,C#, .NET: XML • Recommended by W3C in 1998, XML (eXtensible Markup Language) emerges as the second generation Web language for data interchange on the Web. • Provides text encoding of all data. • Uses a Document Type Definition or Schema to ensure document/data consistency. • Over 200 XML derived languages. • Offer real potential to significantly impact geo-spatial data and systems interoperability on the Web.
5. XML,GML,WMT,C#, .NET: GML • GML Project launched at OGC meeting, April 1999 • GML provides a standard means to encode Geographic Info in XML. • GML separates content from presentation. GML is focused on capturing geographic content. • GML is “styled” into a presentation format such as SVG(Scalable Vector Graphics) for map drawing or other visualizations. • GML is consistent with existing OGC standards for expressing geographic features.
Map Viewed in Web Browser Graphical rendering Map Style Library Stylesheet Styling Engine HTTP TCP/IP GML DataServer Figure. Process of GML Web Mapping
5. XML,GML,WMT,C#, .NET: WMT The Web Mapping Testbed, Phase I, is the first of OGC's planned Interoperability Initiatives, which involve sponsors and participants. Federal agency and corporate sponsors provide funding and a set of objectives related to geoprocessing interoperability. WMT has so far demonstrated two types of applications: Web Mapping Clients, and Web Mapping Servers. The Clients create requests that satisfy the Web Mapping Protocols.
5. XML,GML,WMT,C#, .NET: WMT The main interfaces are the GetMap protocol (which identifies one or more layers to be displayed), the GetCapability Protocol (which allows the client the ability to discover the abilities of a server), and finally the GetFeatureInfo protocol (which allows the client to uncover the attributes of a displayed feature). Web Mapping Servers interpret requests that conform to the WMT protocols and generate appropriate objects that are returned to the querying clients.
5. XML,GML,WMT,C#, .NET: C#, .NET • C and C++: powerful and flexible, but unproductive • C# — Microsoft solution, a modern, object-oriented • building applications for the new Microsoft .NET • serving both computing and communications • .NET — Internet-based integrated solution
6. ExampleA New Spatial Search Engine –Enabling the Intelligent Geographic Information Retrieval in Internet Yuqi,BAI Chongjun YANG Institute of Remote Sensing ApplicationsChinese Academy of Sciences http://www.digitalearth.cn
6. Example Context: Using “www.yahoo.com” to search a text Using “www.mapquest.com” to search a map Question: May we search a map without using “traditional search engine?
6. Example • Scenario: When you are reading news on the web, you maybe meet a place name, for example ‘Afghanistan’, and want to know where it is. Can you just simply select this place name and get the corresponding map?
6. Example a.Design of a ‘New Spatial Search Engine’-1 Interoperability Three Stages: Service Sharing Modularity Component Sharing Compatibility Data Sharing <-
6. Example a.Design of a ‘New Spatial Search Engine’-2 • Design goals • Automation: • get command -> query -> render the result • Interoperability: • with any web mapping systems • Integration: • can be integrated with other existing applications seamlessly and easily.
6. Example a.Design of a ‘New Spatial Search Engine’-3 • Conceptual Design • Modularization: • For the Web Mapping Systems(WMS) • Description: • For the service interfaces of WMS • Registration: • a logically centralized, physically distributed registry centre
6. Example a.Design of a ‘New Spatial Search Engine’-4 • The Conceptual Architecture <-
6. Example b.Prototype System-1 Geo-coding Service Map-providing Service
6. Example b.Prototype System-2 • Software packages used • IBM Websphere UDDI Registry 1.1 • VC++ 6.0 • Standards • SOAP 1.2 • UDDI 2.0 • GML 2.0
6. Example b.Prototype System-3
6. Example b.Prototype System-4
6. Example b.Prototype System-5
6. Example b.Prototype System-6 <-
7. Discussion & Cooperation: a.Would rather provide spatial data service than only data b.Make all things(hardware,software, data, processing, etc.) as interoperable as possible c. International cooperation in developing interoperable technology