Massachusetts Institute of Technology Department of Urban Studies and Planning 11 520 A Workshop on Geographic Information Systems 11 188 Urban Planning and Social Science Laboratory Lecture 10 Introduction to Internet GIS and ArcIMS Nov 9 2005 Joseph Ferreira Jr Based primarily on lecture notes by Visiting Prof Zhong Ren Peng Fall 2003 See Peng and Tsou Internet GIS 2003 John Wiley ISBN 0 471 35923 8 Main Topic Introduction to Internet GIS and ArcIMS Introduction to Internet GIS State of the Art of Internet GIS Introduction to ArcIMS The Road Map of GIS Stand alone GIS Programs Mainframe based monolithic GIS programs Desktop GIS programs Limited or no communication with other computers other than transparently via for example use of a network file server Programs need to run on the mainframe or PC where the program resides Users need access to that machine via a login or dumb terminal session Examples early Arc Info installed on a stand alone mainframe or PC LAN based GIS Programs GIS installed on one or more machines on a Local Area Network LAN GIS programs run on local machines but can share data and printing facilities from the data server or GIS programs run on a server user can access it from any machine inside the LAN Typical Client Server architecture Examples Most current GIS programs Limitations of Stand Alone and LAN based GIS Programs Difficult for user outside the LAN to access Difficult to directly access data that are available outside the LAN Limited GIS users Difficult to mange update and extend What is Internet GIS Internet GIS is a network centric GIS tool that uses the Internet as a primary means of providing access to the functionality e g analysis tools mapping capability of GIS and to the spatial data and other data needed for various GIS applications Internet GIS is an integrated client server and Web Server application Internet GIS typically uses a Web browser as client Internet GIS can be viewed as a distributed objectoriented system Internet GIS is portable and cross platform Internet GIS vs Web GIS What s the difference between the Internet and the World Wide Web Internet refers to the inter connected computer network infrastructure Web is one of many applications that are based on the Internet The term Internet GIS focuses the use of a suite of Internet technologies not only the Web Internet GIS thus has more longevity and is a preferred term Features of Internet GIS Wide accessibility users from the world can access GIS data and analysis tools over the Internet No GIS software is required to install locally Takes advantage of the friendly graphic user interface that is provided by the World Wide Web Users can directly manipulate maps and GIS data over the Web Internet aware GIS software can access remote data anywhere on the Internet Internet GIS can easily incorporate up to date realtime information Basic Components of the Internet GIS Internet GIS State of the Art Static Map publishing Static Web Mapping Interactive Web Mapping Client side Plug ins and Helper Program GIS ActiveX Controls Java based Internet GIS Distributed Geographic Information Services Server Side and Client Side Internet GIS Server Side Internet GIS HTML to GIS server via CGI Common Gateway Interface script Client Side Internet GIS Client side Plug ins and Helper Program GIS ActiveX Controls Java based Internet GIS Hybrid of server and client side Internet GIS Static Map publishing Insert Map images in a text file on the Web Not a GIS Static Web Mapping How does it work Common Gateway Interface When information is collected by a browser it is sent to a HyperText Transfer Protocol HTTP server specified in the HTML form and that server starts a program also specified in the HTML form that can process the collected information Such programs are known as Common Gateway Interface programs or CGI scripts E O Johnson CGI is a simple interface that links Web browser server and other external programs CGI or Dynamic Link Library DLL has three functions It receives user inputs and parses them into parameters of variables to be used in GIS programs It lets Web servers run other GIS programs It interprets output and sends back to browsers Advantages of Static Web Mapping A thin client e g all data processing is done on the server while the client is used only for display and user input Takes full advantage of all GIS software functionality at the server Ubiquitously accessible over the Internet Can handle large database to serve spatial queries Drawbacks of Static Web Mapping Every user request has to go through the Internet to activate a CGI script every time Creates heavy traffic over the Internet Operation is slow because every command even very simple ones like zoom and pan has to be operated on the GIS server Maps are static images User cannot draw a box or a circle or select polygons on the map images Examples of Static Web Mapping VISA International ATM locator http www visa com ESRI s MapObjects Internet Map Server http metrotrip ci waukesha wi us waukesha Map Quest http www mapquest com Interactive Web Mapping Client Side Internet GIS Interactive Web Mapping programs allow 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 GIS ActiveX Controls GIS Plug Ins or Helper Programs GIS plug ins are software executables that run on the browser and interpret the GIS data received from the server GIS plug ins are used in extending the browser to process GIS data While GIS plug ins are small applications GIS helper programs can be large GIS applications or existing GIS software that is located in the user s local machine How Do GIS Plug Ins Work Partition Points for GIS Plug In Examples of GIS Plug ins Autodesk MapGuide http www mapguide com GeoMedia Web Map for Netscape browser Advantages of GIS Plug Ins GIS plug ins enable Web browser to interact with GIS data Some GIS functions i e zoom pan query can be conducted by the plug ins so it can reduce traffic on the Internet GIS plug ins can fetch data from the server on demand Plug ins are easy to control and are not distributed with browsers Drawbacks of GIS Plug Ins Plug ins are not platform independent The GIS vendor has to create different plug ins for different operating systems Unix PC Users have to download different plug ins from different GIS servers GIS plug ins and helper programs have to be installed in the user s machine Security concerns