Coming from various discussions I have had in the GIS and ESRI Users groups in LinkedIn, I decided I should write a log entry describing the three technologies that people discuss frequently, without differentiation between them: the geoweb, web mapping and web GIS. While there are multiple definitions of the three, mine defines the three based on their functionality, differentiating them and drawing clear distinctions.
In essense, the geoweb consists of locationally aware web technologies usually manifested on the world wide web. Web mapping then refers to those online applications that permit users to view or create maps on a web platform, usually with limited or no GIS analysis. Web GIS then refers to Geographic Information Systems that use web technologies as a method of communication between the elements of a GIS.
GIS has been defined numerous times by several scholars and organizations. ESRI, the world’s largest producer of GIS Software defined GIS through the lens of data, map view and model view (source). The United States Geological Survey (USGS) defines GIS as a system capable of capturing, storing, analyzing and displaying geographically referenced information (source). Nicholas Chrisman, a leading scholar in GIS, in his book Exploring Geographic Information Systems, defined GIS as “the organized activity by which people measure aspects of geographic phenomena and processes; represent these measurements, usually in the form of a computer database, to emphasize spatial themes, entities and relationships; operate upon these representations to produce more measurements and to discover new relationships by integrating disparate sources; and transform these representations to conform to other frameworks of entities and relationships. These activities reflect the larger context (institutions and cultures) in which these people carry out their work. In turn, the GIS may influence these structures.” (source) As can be seen by all the definitions, a Geographic Information System has multiple components, including human actors, that work together for a common purpose. These definitions then provide us a first step into clarifying what is the difference between a web GIS and web mapping.
If any of the above definitions are to be considered valid, then mapping is a single component in what is termed GIS, the visualization aspect. Therefore one can define web mapping applications as applications that enable the visualization of geographically referenced data through a web interface available online. While most web mapping applications today allow users to perform some spatial analysis (short path finding algorithms), this does not constitute a GIS application in my mind, as other, simple sorts of analysis are not permitted (imagine spatial queries, buffer analysis, etc).
As web mapping has been clarified, we can now explain what the geoweb is. First of all, the geoweb is considered as a collection of web applications and/or services that are geographically aware. What that means in other words is that applications that somehow are aware of geographic locations, either through geo-ip location or supplemental information as tags or EXIF data in photographs. The uses are multiple, like browsing Flickr photos by location information, load-balancing servers (redirect traffic to the nearest available server to answer requests, etc). The geoweb is therefore an amalgamation of location-aware services available to the public that provide location-based decisions to be made.
The last definition, web GIS, is all that remains. Using any definition of GIS provided above, one will notice there are multiple components. The interaction between the components is usually very direct in desktop GIS. Data, maps and analysis happen on the same computer, so communication is done internally. Enterprise GIS often allows the user to communicate with data remotely, and sometimes even analysis is done remotely. Web GIS enables the communication of all components to happen through the web, enabling diverse data, analysis algorithms, users and visualization techniques that may be hosted at any location on the web.
Of course, the above definitions are the way I understand the world of GIS and location-aware applications. If you have any suggestions or corrections to make on the above, feel free to leave me comments or email me directly.