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Distributed GIS Technology, Components, Applications and Future

Distributed GIS Technology, Components, Applications and Future. April 11 2005 Yang Han. Agenda. Impact of the Internet on GIS GIS Technology: From Centralized to Distributed What is Distributed GIS Why do we Need Distributed GIS Basic Components of Distributed GIS

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Distributed GIS Technology, Components, Applications and Future

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  1. Distributed GISTechnology, Components, Applications and Future April 11 2005 Yang Han

  2. Agenda • Impact of the Internet on GIS • GIS Technology: From Centralized to Distributed • What is Distributed GIS • Why do we Need Distributed GIS • Basic Components of Distributed GIS • The Standards for Distributed GIS • Applications of Distributed GIS • Future of Distributed GIS

  3. Impact of the Internet on GIS Change our lives

  4. Impact of the Internet on GIS The Internet is a modern information system that connects thousands of telecommunication networks and creates an “internetworking” framework. The dramatic success of the Internet and the popular adoption of TCP/IP pushed the development of telecommunication into a new age.

  5. Impact of the Internet on GIS • The GIS community also began to utilize the Internet to develop distributed GIS. • Distributed GIS is a research and application area that utilize the Internet and other internetworking systems to facilitate the access, processing, and dissemination of geographic information and spatial analysis knowledge. • The Internet is affecting GIS in three major areas: • GIS data access • Spatial information dissemination • GIS modeling/processing

  6. Impact of the Internet on GIS • The Internet provides GIS users easy access to acquire GIS data from different data providers. GIS data warehouse and digital libraries are two common forms of Internet data access systems. • U.S. Geospatial Data Clearinghouse Activities under the Federal Geographic Data Committee (FGDC) has been working to build a distributed archive of information for universal access (http://www.fgdc.gov) • Alexandria Digital Library Project funded by the US National Science Foundation established the first distributed library service for spatially referenced data in 1994 (http://www.alexandria.ucsb.edu/ )

  7. Impact of the Internet on GIS • The Internet also enables the dissemination of GIS analysis results and spatial information to a much wider audience than does traditional GIS. • Furthermore, the Internet is becoming a means to conduct GIS processing. It enhances the accessibility and reusability of GIS analysis tools by dynamically downloading or uploading GIS processing components.

  8. Impact of the Internet on GIS • The rapid expansion of low-cost bandwidth on the Internet • A new generation of Web-enabled desktop computers and mobile devices.

  9. Mobile GIS Internet GIS Desktop GIS Distributed GIS GIS Technology: From Centralized to Distributed Mainframe GIS

  10. GIS Technology: From Centralized to Distributed • Mainframe GIS adopted the monolithic computing model; that is, all programs were in the same mainframe computers. User access to GIS data and analysis functions on the mainframe server were through dumb terminals.

  11. GIS Technology: From Centralized to Distributed • Desktop GIS relies on GIS programs on the desktop computers. It has two categories. • The stand-alone desktop GIS has all the GIS functions, user interface, and data in one stand-alone computer. • The LAN-based desktop GIS usually adopts the two-tier client/server model.

  12. GIS Technology: From Centralized to Distributed • Distributed GIS represents a dramatic departure from the traditional two-tier client/server model. Rather than relying on desktop GIS programs, distributed GIS, when fully implemented, does not necessarily require the user to install GIS programs on the user’s desktop. It relies on the Internet and wireless networks for data from anywhere with Internet access. • Internet GIS • Mobile GIS

  13. GIS Technology: From Centralized to Distributed

  14. GIS Technology: From Centralized to Distributed • The mainframe GIS and desktop GIS are traditionally referred to as GISystems, and distributed GIS is referred to as GIServices. The term service here refers to component services; that is, components with certain functions can be downloaded and reassembled together to build larger, more comprehensive services to perform certain tasks.

  15. GIS Technology: From Centralized to Distributed • Traditional GISystems: • Closed, centralized systems that incorporate interfaces, programs, and data. • System is platform dependent and application dependent. • Migrating traditional GISystems into different operating systems or platforms is difficult. • Different GIS applications may require different GIS packages and architecture design. • Every element is embedded inside traditional GISystems and cannot be separated from the rest of the architecture. • Traditional GISystems include mainframe GIS and stand-alone desktop GIS.

  16. GIS Technology: From Centralized to Distributed • Client/server GISystems or current desktop GIS are based on generic client/server architecture in network design. • The client-side components are separated from server-side components. • Client/server architecture allows distributed clients to access a server remotely by using distributed computing techniques or database connectivity techniques. • The client-side components are usually platform dependent. Each client component can access only one specific server at one time. • Different geographic information servers come with different client/server connection frameworks, which can not be shared.

  17. GIS Technology: From Centralized to Distributed • Distributed GIServices • The most significant difference is the adoption of distributed-component technology, which can connect to and interact with multiple and heterogeneous systems and platforms and without the constraints of traditional client/server relationship. • Under a distributed GIServices architecture, there is no difference between a client and a server. Each GIS node embeds GIS programs and geodata and can become a client or a server based on the task at hand. • A client is defined as the requester of a service in a network, and a server provides a service. • A distributed GIServices architecture permits dynamic combinations and linkages of data and GIS programs via networking.

  18. GIS Technology: From Centralized to Distributed

  19. What is Distributed GIS? • Internet GIS • Distributed GIS • Web-based GIS • Web GIS

  20. What is Distributed GIS? • The Internet is any network composed of multiple, geographically dispersed networks through communication devices and a common set of communication protocols. • The World Wide Web is a networking application supporting a HTTP that runs on top of the Internet. The Internet is not synonymous with the World Wide Web. • The Internet refers to the network infrastructure, while the Web refers to one of many applications that run on top of the Internet.

  21. What is Distributed GIS? Internet GIS Web-based GIS The Internet WWW

  22. What is Distributed GIS? • Distributed GIS is defined as a network-centric GIS tool that uses the Internet or a wireless net-information, disseminating spatial information and conducting GIS analysis. • The client devices could be desktop computers, laptop computers, PDAs, or mobile phones. • The servers could be distributed in multiple locations. • Protocols could be HTTP, WAP, FTP, Common Object Request Broker Architecture (CORBA) protocols, and ODBC libraries.

  23. What is Distributed GIS? Wireless GIS Distributed GIS Web-based GIS Internet GIS Other Internet GIS

  24. What is Distributed GIS? • Distributed GIS is an Integrated Client/Server Computing System • Distributed GIS is a Web-Based Interactive System • Distributed GIS is a Distributed and Dynamic System • Distributed GIS is Cross-Platform and Interoperable

  25. What is Distributed GIS? • Distributed GIS is an Integrated Client/Server Computing System • Distributed GIS applies the dynamic client/server concept on performing GIS data sharing and analysis tasks. • The connections between the client and server are established according to a communication protocol, mainly TCP/IP. • Depending on the amount of processes performed on the client side, the client could be “thick” or “thin”. • In addition, the concepts of client and server are relative; any computer could be both a server if it provides services to other computers and a client if it requests services from other computers.

  26. What is Distributed GIS? • Distributed GIS is a Web-Based Interactive System • The distributed GIS relies on the WWW and its add-ons to provide interactively between the user and the distributed GIS programs. • In addition to the interactivity provided by HTML, XML, or WAP, distributed GIS can also handle vector-based GIS data. It enables users to manipulate GIS data and maps interactively over the Internet or wireless networks. • Users can perform GIS functions such as map rendering, spatial queries, and spatial analysis using a Web browser or other Internet-based client programs.

  27. What is Distributed GIS? • Distributed GIS is a Distributed and Dynamic System • Geospatial data are usually distributed across different departments within an organization and among organizations, either on intranets or on the Internet. Distributed GIS can potentially query and extract these distributed databases rather than simply downloading the data directly into the end users’ local machines to combine with local data. • Distributed GIS clients should be able to search, download, and assemble analysis tools on demand. The clients have control over the functions required for a particular task.

  28. What is Distributed GIS? • Distributed GIS is Cross-Platform and Interoperable • Distributed GIS can be accessed across platforms regardless of what operating system the user is running. The clients of distributed GIS tend to be able to run in a variety of computing environments and platforms. • To be able to access and share remote GIS data and functions, distributed GIS programs require high interoperability. The Open Geodata Interoperability Specification and Geography Markup Language (GML) by the OpenGIS Consortium (OGC) are attempting to lay the ground rules for GIS interoperability.

  29. Why do we Need Distributed GIS • Uniqueness of Geographic Information on the Internet • Heterogeneous Format, resolutions, scales, times, and domains • The power of GIS operations/functions The value of geographic information will increase dramatically by providing GIS users with the capability of GIS operations.

  30. Why do we Need Distributed GIS • The disadvantage of the traditional GIS • The high price of GIS software package. • Inaccessibility to the Desktop GIS from locations other than the computer on which the desktop GIS software is installed. • Difficult to customize. • Proprietary technology and the lack of interoperability.

  31. Why do we Need Distributed GIS • Management Perspective • Globalization of geographic information access and distribution. • Decentralization of geographic information management and update

  32. Why do we Need Distributed GIS • User Perspective • The need of distributed GIS processing to cope with increasing size and variety of geospatial data sets • The need for customizable GIS modules for software package specialization • The demand for location-based information from the general public due to the popularity of the Internet and mobile devices

  33. Why do we Need Distributed GIS • Implementation • Installation is not necessary

  34. Client Client Client Web Server with Application Server Map Server Data Server Basic Components of Distributed GIS

  35. Basic Components of Distributed GIS • The Client • HTML HTML-based client has very limited user interactivity. It is particularly inadequate for users to interface with maps and spatial objects.

  36. Basic Components of Distributed GIS • The Client • DHTML Uses client-side scripting like JavaScript or VBScript to make the plain HTML dynamic • ActiveX controls General component ware that can plug into any application that supports Microsoft’s Object Linking and Embedding (OLE) standard. • Java Applets Reside at the Web server and are downloaded from the server and executed on the client at runtime. They allow the user to interact directly with the spatial features on the map. • Plug-ins Software executables that run on the browser to extend the capabilities of Web browsers.

  37. Basic Components of Distributed GIS • Web Server and Application Server • Web Server (HTTP Server) Respond requests from clients • Sending existing HTML document or ready-made map images to the client • Sending Java applets or ActiveX controls to the Web client • Passing requests to other programs and invoking other programs such as CGI that could process the queries

  38. Basic Components of Distributed GIS • Web Server and Application Server • Application ServerTranslator or connector between the Web server and the map server • Establishing, maintaining, and terminating the connection between the Web server and the map server • Interpreting client requests and passing them to the map server • Managing the concurrent requests and balancing loads among map servers and data servers • Managing the state, transaction, and security

  39. Basic Components of Distributed GIS • Map Server (GIS Server, spatial server) A major workhorse component that fulfills spatial queries, conducts spatial analysis, and generates, and delivers maps to the client based on the user’s request. • Filtered feature data that are sent to the client program for user manipulating • A simple map image in a graphic format, such as GIF or JPEG, or a graphic element map that is composed of discernible map elements with predefined colors, styles, legends, and so on.

  40. Basic Components of Distributed GIS • Data Server • Serves data, spatial and nonspatial, in a relational or nonrelational database structure. • A client application such as a Web client or a map server gains access to the database through the SQL. Therefore, a database server is often referred to as a SQL server. • Database middleware is often used to access different databases. There are three major database middleware: ODBC, Java Database Connectivity (JDBC), and Object Linking and Embedded Database (OLE DB) ActiveX Data Object (ADO). Through SQL, ODBC, or JDBC drive, the client application can query, retrieve, and even modify database records in the database server

  41. Client Client Client Web Server with Application Server Map Server Data Server Basic Components of Distributed GIS

  42. Basic Components of Distributed GIS thin client architecture VS. thick client architecture

  43. Basic Components of Distributed GIS Thin Major advantages of this model are: 1. Central control 2. Easy for data managing 4. Generally cheaper 5. Integration possibilities Disadvantages are: 1. Response time low 2. Less interactive 3. Vector data does not appear in client side

  44. Basic Components of Distributed GIS Thick Major advantages of this model are: 1. Images are not restricted to GIS and JPEG 2. Vector data can be used 3. More functions are available on the client side And disadvantages to this architecture are: 1. Platform and browsers are incompatible 2. Users are required to install additional software

  45. The Standards for Distributed GIS • Open GIS by Open GIS Consortium (OGC) • ISO/TC 211 by Technical Committee tasked by the International Organization for Standardization (ISO)

  46. The Standards for Distributed GIS • The main goals of OGC are the full integration of geospatial data and geoprocessing resources in mainstream computing and the widespread use of interoperable geoprocessing software and geodata products throughout the information infrastructure. • ISO/TC 211 emphasizes a service-oriented view of geoprocessing technology and a balanced concern for information, application, and system.

  47. The Standards for Distributed GIS OGC • The OGC, a broad-based alliance of government agencies, research organizations, software developers, and systems integrators, is engaged in a multi-year effort to define open GIS and to develop a set of requirements, standards, and specifications which support it. • The overall goal is to encourage software developers and integrators to adhere to these requirements, and through time create tools, databases, and communications systems that maximize the utility of systems and resources and take advantage of technological advances.

  48. The Standards for Distributed GIS OGC • Major areas of research and development within OGIS include defining a geodata type hierarchy that comprises simple and complex features, maps and coverages, images, and field datasets (and specifying the relevant interfaces); developing a consistent approach to metadata to support data collections and browsing; enabling the concept of ‘‘information communities’’ which share common definitions, information semantics, and data dictionaries/thesauri; and defining the basic data structures required for implementation.

  49. The Standards for Distributed GIS OGC • The three broad requirements for Open GIS • Interoperable applications • Shared data space • Heterogeneous resource browser • An open GIS architecture must provide robust methods for accessing multiple forms of data using multiple software environments.

  50. The Standards for Distributed GIS OGC • Open GeoData Interoperability Specification (OGIS) • initiated by the Open Systems Foundation • a comprehensive object based framework to support distributed access to geodata and geoprocessing resources • The OGC was set up to oversee the development of the OGIS

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