Presented at the MAC URISA spring meeting on May 12th.

1. Internet-enabled GIS Using Free
and Open Source Tools
John Reiser
jreiser@njgeo.org

2. What exactly is Open Source?
• Freedom to allow others to adapt and reuse
while retaining some rights over code
• Community-driven software
• Precursor to the Open Content movement
• Eric Raymond's quot;The Cathedral and the Bazaarquot;

3. The Cathedral and the Bazaar
quot;I believed that the most important software
needed to be built like cathedrals, carefully
crafted by individual wizards or small bands of
mages working in splendid isolation, with no
beta to be released before its time.quot;
quot;The Linux community seemed to resemble a
great babbling bazaar of differing agendas and
approaches out of which a coherent and stable
system could seemingly emerge only by a
succession of miracles.quot;

4. No Miracles Necessary
• Open source does work
• Thousands of software packages are available
under open source licenses
– Operating systems, development tools, web
browsers, web and file servers, communications
tools, graphic design applications, etc…
• All with no upfront monetary cost
• How does GIS fit in?

5. The Cathedral

6. The Bazaar

7. Open Source GIS
• Software that allows us to share our data with
everyone using open standards
• Software that we can modify and improve
• GIS data released under an open license
• GIS data updated and enriched by community
input and participation

8. Open Source GIS
• Developing an open source GIS has many
benefits
– Low-cost of entry
– Adaptable and extendable
– Entry into the greater open source community
• quot;Open Source doesn't come with supportquot; is no
longer a valid excuse
• Several companies now provide support to OS
GIS packages

9. Sharing Data: Accessibility
• We can easily share data now
– FTP
– ZIP files posted to the web
• Helps GIS users, but outsiders are left in the dark
• Inviting, easy to use map interfaces are the new
way to share

10. Making GIS Accessible

11. NYCityMap
gis.nyc.gov/doitt/nycitymap/

12. Delivering On Change
whitehouse.gov/change/

13. Getting the parts together
• Protocols
– Web Map Service
– Web Feature Service
– Keyhole Markup Language
• Server side tech
– MapServer and/or GeoServer
– Tilecache
• Client side
– OpenLayers
– Google Maps and Virtual Earth (free but not OS)

14. Configuration of a Web Map
MapServer
Server Client
GIS
Data
GeoServer TileCache OpenLayers
Map
Other WMS
Cache

15. Web Map Service
• WMS is a protocol for requesting rendered map
tiles from a GIS server
• Allows access to the attribute information via
XML
• REST-ful protocol – necessary info within the URL

16. Web Feature Service
• WFS allows for retrieval of GIS features and
properties from a remote server
• WFS also allows updating GIS data on a remote
server
• Returns XML data

17. KML
• Once a quot;closedquot; language, Google pushed for its
adoption as an open standard
• KML is a subset of XML and related to GML
• KML stores vector data along with symbology
• KML can act as a wrapper for WMS services

18. Choosing a Server
• MapServer and GeoServer fill similar roles, but
there are some things to consider in choosing:
– Hosting environment
– Focus on rendering data or manipulating data
– Familiarity with command-line interface
– Patience

19. MapServer – mapserver.org

20. MapServer
• MapServer is robust software
– launched mid-1990s, currently version 5.4.0
• MapServer is lightweight
• Runs in either Apache httpd or IIS
• MapServer supports many file formats
• Easy to install
• More difficult to configure

21. GeoServer – geoserver.org

22. GeoServer
• GeoServer is also robust software
– launched 2001, currently version 1.7.4
• Written in Java, runs in Apache Tomcat
• Complicated to install in shared hosting
environment
• Easy to configure

23. Tile-based Mapping
• Common complaint of ArcIMS is that the service
is painfully slow
• The map extent is rendered from GIS data for
every request
• Caching pre-rendered maps allows the server to
send a static file without GIS processing

24. Tile-based Mapping
• Enforce a set of scales at which the map is
rendered
• Break each map scale into a grid of rendered
map tiles
• Map tiles can be stored on disk after rendering
• Removes the need to render from data for each
map request
• TileCache can manage the rendered tile cache

25. TileCache – tilecache.org

26. TileCache
• TileCache sits between the client and server
• Client requests map tiles (using WMS)
• TileCache checks the stored tiles
• If it exists, it returns the rendered tile to client
• If tile is missing, it passes the request to a GIS
server
• Once it receives the rendered tile, TileCache
stores the tile and sends it to the client

27. TileCache
• Written in Python, with extensions for server
environment
• Can cache tiles directly from MapServer or any
WMS-capable GIS server
• Can reduce the strain on infrastructure and lower
costs

28. OpenLayers – openlayers.org

29. OpenLayers
• JavaScript library for implementing a quot;Google
Mapsquot; style interface
• Allows interactive mapping within most modern
web browsers
• Originally from the same company as
TileCache, now a project of OSGeo
• Supports both WMS and WFS
• Supports tiles from Google Maps, Virtual Earth
• Highly customizable

30. Information Warehouse
njgin.state.nj.us

31. NuMapsDemographicDrapes
demos.numaps.com.au

32. Freedom to Mix and Match
• You could develop your interactive map using
entirely open source software
– quot;OpenGeo Architecturequot;
• You can mix and match parts as necessary
– ArcGIS &OpenLayers
– MapServer& Google Maps/Google Earth
• Open standards give you the freedom of choice

33. Open Source Community
• The strength of OS software comes from the
community
• quot;Given enough eyeballs, all bugs are shallow.quot;
• Propose or contribute new functionality
• Community is not limited to software

34. Collaboration
• Data can benefit from collaboration
• Parcels from a surveyor and tax assessor
• Free alternatives to high-cost data
– OpenStreetMap
• POI databases become truly valuable once
released to the crowd to update
• Just beginning to explore the value in
Volunteered Geographic Information

35. OpenStreetMap – openstreetmap.org

36. GeoNames – geonames.org

37. GeoCommons – geocommons.com

38. GeoCommons Finder!

39. GeoCommons Maker!

40. Open Source Community
• Equality, transparency and collaboration
• A community of passionate individuals
• Use the software and become part of something
greater
• Consider sharing your data with the community

41. Resources
• Open Source Initiative
– http://www.opensource.org/
• Open Source Geospatial Foundation (OSGeo)
– http://www.osgeo.org/
• Source images for quot;Cathedralquot; & quot;Bazaarquot; are GNU licensed images from Wikimedia Commons
– http://commons.wikimedia.org/wiki/File:Catedral_Metropolitana_de_Sao_Paulo_1_Brasil.jpg
– http://commons.wikimedia.org/wiki/File:Bd_bazaar.jpg
• Full text of quot;The Cathedral and the Bazaarquot; is available online:
– http://www.catb.org/~esr/writings/cathedral-bazaar/
• Web Mapping Illustrated is a great resource for developing your own web maps
– http://oreilly.com/catalog/9780596008659/
• Whitepaper on quot;OpenGeoquot; Architecture from GeoServer
– http://opengeo.org/publications/opengeo-architecture/ (published April 2009)