Tools Of The Geospatial Web
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Transcript of Tools Of The Geospatial Web
Tools of the Geospatial Web
Last week - Google Maps
It allows users to easily load and internet map through an API
This kind of map is classified as a Open, Reusable map
This Week
Look at the API concept
Look at AJAX in greater detail
Look at other non-API Web Mapping Applications
What is API
An API is an Application Programming Interface
It web-developers to leverage the power of other applications through their own websites
Google Maps API
This API allows us to leverage the methods and classes developed by Google for this application
What does this look like?
<title>Google Maps JavaScript API Example</title>
<script src="http://maps.google.com/maps?file=api&v=2&key=abcdefg"
type="text/javascript"></script>
<script type="text/javascript"> function initialize() { if (GBrowserIsCompatible()) { var map = new
GMap2(document.getElementById("map_canvas"));
map.setCenter(new GLatLng(37.4419, -122.1419), 13);
Event handler and its place
<body onload="initialize()" onunload="GUnload()">
<div id="map_canvas" style="width: 500px; height: 300px"></div>
</body>
More Information
http://www.google.com/apis/maps/documentation/introduction.html
Other APIs
Yahoo! Maps http://developer.yahoo.com/maps/
Virtual Earth SDK http://dev.live.com/virtualearth/sdk/
ArcWeb Services http://www.esri.com/software/arcwebservices/index.html
AJAX
Ajax - Asynchronous JavaScript and XML
Ajax allows the Web browsers to send GET and POST requests without refreshing the browser
POST and GET
Are Methods that are stated in submission forms
Eg. Database search http://first6years.org/?q=node/14
GET VS POST
Get is used primarily in querying data
Post is used for posting or uploading data into a database
What does AJAX do?
In AJAX POST and GET are managed through the AJAX engine or javascript object
This is done asynchronously meaning that code execution doesn’t wait for a response from a server
What does the user see?
This creates a seamless experience allowing for richer experiences similar to the desktop environment.
QuickTime and aﾪTIFF (Uncompressed) decompressor
are needed to see this picture.
Non-API Internet GIS Applications
Other Internet GIS applications allow for more robust tools and customization of both Primary and secondary data.
Most now come with Out-of-the-Box development tools
Open SourceApplications
Mapserver - OGC Compliant first designed by NASA http://mapserver.gis.umn.edu/
Geoserver- OGC Compliant with an interface similar to Open Layers http://geoserver.org/
Application Architecture
These Web Mapping Systems run a webserver or integrate with one
Store Spatial data in a directory and provide an interface for creating your mapping application
Map files
Data is then stored in an XML based Map file which is used to define the look and feel of the web map
Generally these files are used on one map at a time
Break
After the break we will look at these two different applications in greater detail
