1. CS 128/ES 228 - Lecture 14b1 Maps on the Internet

2. CS 128/ES 228 - Lecture 14b2 WWW + GIS = WebGIS Universal access No special software needed Data (map?) directly to consumer

3. CS 128/ES 228 - Lecture 14b3 Software Terminology Client – the user, or the user’s computer. Clients are assumed to be running “generic” software, e.g. Web browser Server – the remote computer Servers may be running all sorts of software. Note: one copy “serves all”

4. CS 128/ES 228 - Lecture 14b4 The Key Question Who performs the computation that produces the map?

5. CS 128/ES 228 - Lecture 14b5 Three Answers Server, in advance Produce.jpeg or.gif Server, on the fly In response to requests from the web Client Server gives the client the data and says, “Have fun”

6. CS 128/ES 228 - Lecture 14b6 Static Maps Limited utility as designer must have thought of all possibilities. Good for “how to get here” maps

7. CS 128/ES 228 - Lecture 14b7 Dynamic maps - Servers

8. CS 128/ES 228 - Lecture 14b8 Why should the server do the work? Server has all the data Can “cache” answers Server has better hardware BUT Server can easily be overloaded with requests

9. CS 128/ES 228 - Lecture 14b9 Dynamic maps - Clients

10. CS 128/ES 228 - Lecture 14b10 Why let the client do the work? Distributes computation across many machines Better customization BUT Must transfer lots of data Client needs data manipulation (GIS?) software

11. CS 128/ES 228 - Lecture 14b11 Real-Time Data (another “dimension”) The server can “be fed” data that is gather in “real-time” and this data can be sent in response to requests Water (river) levels Traffic Seismographic data

12. CS 128/ES 228 - Lecture 14b12 How is it done? ESRI Product – ArcIMS (Internet Map Server) Apparently used for Western NY site Various competitors Intergraph (Geo Media Web Map) MapInfo (MapXtreme) Autodesk (MapGuide)

13. CS 128/ES 228 - Lecture 14b13 Credits Much of the material (including the figures) came from http://www.ist.psu.edu/faculty_pages/bacasto w/gis/32 Other info came from Serving Maps on the Internet, by Christian Harder, ESRI Press, 1998.