1. Internet GIS: The State of the Art and Future Development Zhong-Ren Peng, Ph.D. Associate Professor Director, Center for Advanced Spatial Information Research (CASIR) University of Wisconsin – Milwaukee zpeng@uwm.edu February 12, 2003

2. 2 The Road Map Mainframe GIS Desktop GIS Internet GIS Mobile GIS Time Accessibility

3. 3 Internet GIS Evolutions Static Web Mapping HTML to GIS server via CGI script Interactive Web Mapping Client-side Plug-ins and Helper Program GIS ActiveX Controls Java-based Internet GIS Distributed Internet GIS CORBA/JAVA Model COM+/ActiveX Model Web Services.Net model GML, WFS

4. 4 InteractivityLowHigh Low Static Map publishing Static Web Mapping Interactive Web Mapping Distributed GIS Functionality Static map images CGI Forms Tables ISAPI NSAPI Dynamic HTML Scripts Plug-ins ActiveX controls Java Applets Servlets JavaBeans Java Applets ActiveX controls CORBA/Java DCOM/ Object-based documents Web Services.NET model GML WFS

5. 5 Static Web Mapping How does it work? WWW Browser WWW Server (http) CGI or DLL GIS Server User Request Deliver Results Send Variables Return Results Invoke Translate Results

6. 6 Drawbacks of Static Web Mapping Every user request has to go through the Internet to activate CGI script every time. Creates heavy traffic over the Internet, because every command (even very simple ones) has to be operated on the GIS server. Maps are static images. HTTP/CGI is stateless. So users cannot draw a box or a circle or select spatial features directly on the map images.

7. 7 Interactive Web Mapping Interactive Web Mapping allows the user to manipulate GIS data and conduct GIS analysis at the client/user side, including: GIS Plug-Ins and Helper Programs GIS Java Applets (e.g., ArcIMS) GIS ActiveX Controls (e.g., GeoMedia Web Map)

8. 8 Limitations and Problems of Current Internet GIS Not Interoperable; Client-side applications can only communicate with its own kind of server. Cannot access different data from different server. Client-side applications cannot talk with each other. Slow performance. Limited Functionality. Some output are images with poor quality.

9. 9 Trends of Internet GIS Distributed GIS for GIS professionals. LEGO-like distributed GIS components GIS Web Services for General Public Access. Geographic Markup Language (GML) Web Feature Services Scalable Vector Graphics Interoperable Geospatial Data GML

10. 10 LEGO-like Distributed Components and Data Objects The LEGO metaphor refers to children’s toy blocks that can be interlocked and stacked. LEGO-like distributed components refer to software modules that can be moved and combined to form a dynamic GIS package on demand. Distributed components will be independent from different operating systems, hardware, network environments, vendors, and applications – Interoperable.

11. 11 GIS component Geodata object User Scenario: Map Display (RLIS) User machine: node-A Mike Dynamic Construction GIS node-A (Client) GIS nodes (Servers) Original Setting GIS node-A GIS node-B GIS node-C Migrating Connecting Task completed (restore original setting) GIS node-A GIS node-B GIS node-C LEGO-like Distributed GIS Model

12. 12 Two approaches to access distributed objects dynamically Remote connections; Object migration.

13. 13 Dynamic Construction for GIS Components HTTP b). Migrating GIS components. a). Invoking GIS components remotely RPC GIS Node-A GIS Node-B Client-side Component Service GIS Node-B HTTP Server GIS component GIS Application Component Container Client Stub GIS component Server-side Component Service Server Skeleton

14. 14 Dynamic Construction for Geodata Objects b). Migrating data objects a). Connecting data objects remotely GIS Node-A Data Container (Local Disk) FTP SQL GIS Node-A GIS Node-B Database Server Database connectivity API: (JDBC or ODBC) Data object GIS Node-B FTP Server Data object GIS Application

15. 15 A Thick Client Solution for a Simple task on a fast network connection Client components Server components GIS buffering component Buffering component downloaded from the server

16. 16 A Thin Client Solution for a Complex task on a slow network connection Client components Server components GIS TIN-model component TIN Modeling result is downloaded from the server

17. 17 Data Migration GIS task: Buffering Network: 10MB Ethernet Buffering component Client-side GIS Component Wisconsin LIS Server-side Data Objects Wisconsin LIS [Wisconsin LIS] is downloaded from the server

18. 18 Remote Data Access TIN modeling, Network: 56K modem TIN-modeling component Client-side GIS component Wisconsin DEM Server-side Data Objects

19. 19 CORBA/JAVA Model Implementation GIS Server Database ORB CORBA Server Application Server ORBS Web Browser Java Applet Web Server HTTP Request Load Applet CORBA/I IOP Client Tier Middle TierServer Tier EJBS

20. 20 DCOM/ActiveX model Implementation

21. 21 Geography Markup Language (GML) GML is an XML encoding for the transport and storage of geographic information. Includes both the geometry and properties of geographic features. GML standard is being developed by the OpenGIS Consortium.

22. 22 What is GML GML Is a means to encode geospatial data GML is a means to transport geospatial data over the Web GML is a means to store geospatial data. GML Is NOT a Presentation Language for Data Display GML Is NOT A Programming Language for Data Processing

23. 23 Why GML? ArcView shapefile ArcInfo coverage Intergraph CGM Mapinfo AutoCAD Oracle Spatial

24. 24 Why GML? ArcView shapefile ArcInfo coverage Intergraph CGM Mapinfo AutoCAD Oracle Spatial GML

25. 25 Why GML? Interoperability! 1. To describe spatial features based on a common data model – OGC ’ s simple feature model; 2. To use a set of basic geometry tags to describe the spatial features (Standard metadata); so that they can be easy to find and interpret. 3. To create a mechanism for creating and sharing application schemas, so that different data set created by different parties can be easily integrated.

26. 26 GML – An Example 10.0 2.0 OR 10.0,2.0

27. 27 GML Schema: -- An Example

28. 28 XLink and XPointer to form Geospatial Web

29. 29 How to Display GML data on the Web Scalable Vector Graphic file, A W3C standard format. Works directly with the Web browser. Requires a SVG plug-in (free from Adobe or other vendors).

30. 30

31. 31 How To Extract data OpenGIS Web Feature Server An OpenGIS implementation specification Can extract data from the data store in the data’s original formats. Transform extracted data to GML. Transport the extracted data to the Web client.

32. 32 An example

33. 33 Clear Vector Map

34. 34 Advantages of GML+SVG+WFS Standard-based, Non-proprietary Interoperable GIS components and data, Feature-level data exchange. Text-based, easy to understand High quality maps on the Internet, Fast response on the client-side.

35. 35 Application Tier Listener Business Facade Business Logic Data Access Database User Interaction and Presentation Database Tier Presentation Tier ServiceRequestServiceResponse DesktopLaptopPDAMobile phone A Web Service /.NET Model for A Distributed GIS

36. 36 Web Service Presentation Layer The editor -- editing the data and saving the change of the data. The viewer -- displaying the underlying data but does not allow the user to change the data. The viewer -- a component container that user can use it to locate, retrieve and assemble other “operator” components such as buffer analysis, spatial overlay, projection conversion, etc.

37. 37 Web Service Listener 1. Receive incoming service requests, parsing the messages, and dispatching the request to the appropriate method on the business facade; 2. Package the response from the business facade into a message and send that back to the client; 3. Handles requests for contracts and other documents about the Web Service.

38. 38 Web Service Business Facade Provides a simple interface that maps directly to operations provided by the business logic layer. In a simple Web Service, all the business logic might be implemented by the business facade. Operators are located in the Business Logic layer.

39. 39 Web Service Business Logic Business Logic uses Operators to transform, combine, or create data, and generate outputs. Operators offer functions of geoprocessing and analysis tools, e.g., buffer analysis, spatial overlay, projection conversion, etc. Operators can be implemented by using Simple Object Access Protocol (SOAP). SOAP is an XML-based Remote Procedure Call that allow other programs to invoke.NET components and applications remotely.

40. 40 Data Access Layer The data access layer presents a logic view of the physical data to the business logic layer. The purpose is to isolate business logic from changes to the underlying data. Catalogs and Repositories of data, as well as Metadata, Names and Relationships components are located in the data access layer.

41. 41 Catalogs and Repositories  Catalogs are collections of metadata, or information repositories about other data objects and operators. Data and service providers use catalogs to list and advertise the availability of data and services. The user searches for catalogs first before getting to the data repositories. Catalogs can be implemented by using Web Service Definition Language (WSDL). WSDL is used to define the functions and services of.NET components.

42. 42 Catalogs and Repositories  Repositories are collections of data. Each item is given a name within the repository. Given a name, a repository can find the resource. Repositories can be implemented using Universal Discovery, Description, and Integration (UDDI). UDDI is a searchable registry database that stores the metadata of.NET components and allow other programs to search/access these components

43. 43 Data Layer The “data” layer include data, metadata, names and relationships required by the Web Service. Data are raw information about an object. Metadata is descriptions about the data. Names are used to register and find data. A name makes sense only within a content or namespace. In a repository, a data name together with the repository name can be used to identify and locate data items. Relationships are links between named items.

44. 44 Listener Business Facade Business Logic Data Access Database User Interaction and Presentation data, metadata, names and relationships Operators (SOAP) Viewer and Editor ServiceRequestServiceResponse DesktopLaptopPDAMobile phone Catalogs and Repositories Simple Operations Dispatcher

45. 45 Mobile GIS Accessing GIS data and functionality via wireless devices. –Laptop Computers, –Personal Digital Assistants, –Cellular phones (WAP phone or other Web- enabled smart phones).

46. 46 A Simplified Cellular Network Mobile Switching Center Web Hosts/Servers

47. 47 Wireless network Telecommunication Service Providers Laptop/ PDA with CDPD modem Base Station Mobile Switching Center Gateway Servers Web Servers w/ GIS server Web Browsers Internet TCP/IP Mobile GIS Architecture

48. 48 Mobile GIS Architecture Using WAP Phones GATEWAY Encoders and Decoders CLIENT Web Server and Application Server Encoded Requests Requests WAE User Agent Encoded Response Response (Content) Content CGI Scripts etc.

49. 49 What do these mean for LIS? Going online, going mobile Provide data and processing tools online. Provide GML conversion tools. Provide editing tools for authorized online data editing. Downloadable and interoperable GIS components. Feature-level data search and download on-line. Inter-connected geospatial data Web.

50. Questions and Comments? http://www.uwm.edu/~zpeng