Databases and web mapping the Open Source way
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This document provides an introduction to using open source tools for databases, web mapping, and geospatial querying. It discusses using PostgreSQL with PostGIS for spatial databases, connecting to databases from MapServer, and using OpenLayers to add interactive maps to web pages. Finally, it mentions additional open source web mapping tools like MapGuide Open Source, Mapfish, and Mapchat.
Databases and web mapping the Open Source way
- 1. Databases and Web Mapping the Open Source Way Open Source GIS Masterclass, Lancaster University January 2010 Jo Cook OA Digital j.cook@oadigital.net 01524 880212
- 2. Introduction
- 3. Introduction 3 2 1
- 4. Databases + www.postgresql.org postgis.refractions.net ● Serverbased database (not like access) ● Enterpriselevel, with support for transactions and multiple users
- 5. How to connect to a database ● HOST: localhost, 192.168.3.40, myserver.com ● DATABASE ● USERNAME ● PASSWORD ● PORT: Usually 5432
- 7. Getting spatial data into PostgreSQL ● OGR2OGR ● SHP2PGSQL Syntax: $shp2pgsql /location/of/file.shp tablename s coordinate system W latin1 | psql d database U username W h host p port
- 8. Querying data ● SQL: Structured Query Language SELECT some comma delimited columns FROM your_table WHERE some condition is met; ● Use PSQL from command line or PgAdmin3
- 9. Spatial Querying ● Find out which county a point is in: SELECT name_2 FROM tblcounties WHERE st_within(geomfromtext('point(1.3 54.26)', 4326), the_geom); ● Find out which counties border Lancashire: SELECT a.name_2 FROM tblcounties a, tblcounties b WHERE b.name_2='Lancashire' AND a.the_geom && b.the_geom;
- 10. Map Servers
- 11. Types of Map Server ● Minnesota Map Server (aka Mapserver) cgi program on a web server. Configuration via text files ● Geoserver javabased program. Configuration via web interface
- 13. Checking the map file ● SHP2IMG $shp2img m /location/of/mapfile.map o /location/of/outputfile.png ● WITH THE BROWSER http://yourserver.com/cgibin/mapserv? map=/location/of/mapfile.map&mode=map
- 14. Connecting to PostgreSQL from Mapserver LAYER NAME "province" STATUS ON TYPE POLYGON CONNECTIONTYPE POSTGIS CONNECTION "host=localhost port=5432 dbname=canada user=postgres password=postgres" DATA "the_geom from province" END
- 16. Structure of a web page <html> <head> <title> My Home Page </title> </head> <body> HELLO WORLD! </body> </html>
- 17. Scripting ● SERVERSIDE: php, asp ● CLIENTSIDE: javascript
- 18. And finally...Web Mapping <html> <head> <script src="http://www.openlayers.org/api/OpenLayers.js"></script> <script type="text/javascript"> var map; function init() { map = new OpenLayers.Map('map'); mylayer = new OpenLayers.Layer.MapServer( "World Map", "http://localhost/cgibin/mapserv.exe", {map: 'C:/world_mapfile.map'}); map.addLayer(mylayer); map.zoomToMaxExtent(); } </script> </head> <body onload="init()"> <div id="map" style="width: 600px; height: 300px"></div> </body> </html>
- 19. Base Mapping and Map Controls ● Can use base data from Google, Microsoft, Yahoo, Openstreetmap etc, but may need to reproject to EPSG 900913 (spherical mercator) ● Can add map controls such as layer switchers, coordinates, reference maps and so on
- 21. And Finally... Open Source Web Mapping is Great Fun!!! This work is licenced under the Creative Commons AttributionShare Alike 2.0 UK: England & Wales License. To view a copy of this licence, visit http://creativecommons.org/licenses/bysa/2.0/uk/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California 94105, USA. Jo Cook OA Digital http://oadigital.net j.cook@oadigital.net +44 (0)1524 880212