Geoide Architecture
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Explanation Geoide Architecture
Geoide-client
The Geoide client works with the Flash plugin. Advantages are:
- Plugin is widespread and if necessary it can be installed quickly;
- User-friendly, interactive service, moreover because map elements are known as vector objects to the client (unlike raster data);
- Also works on relatively slow connection speed due to strong compression;
- Easily customizable for specific applications (OO-programming with ActionScript2);
Geoide-server
This is the server component of Geoide with tasks like:
- Informing the client about the available maps and their properties;
- Controlling access security to map data;
- Collecting GIS data from the WFS (vector data) and WCS (raster data);
- Converting the GIS data in a flash file using the format specification and send it to the client;
- Converting attribute data from GIS objects to XML and send it to the client;
Web Feature Service
The Web Feature Service (WFS) has the following functions (according to OpenGIS specification):
- Informing a WFS client of the available data types ( "map layers" of the type of point, line or polygon) and metadata (definitions of attributes);
- Selecting data (spatial and alphanumeric) of GIS-objects according to a standard protocol from different types of data sources (Shapefile, Oracle Spatial, MapInfo, etc) and send it to the WFS client in GML format or as Java objects.
Geoide can use both a local and remote WFS server.
Web Coverage Service
The Web Coverage Service (WCS) has the following functions (according to OpenGIS specification):
- Informing about available grid layers (aerial, scanned topography, etc.);
- Selecting, according to a standard protocol, a clip from raster data of different formats (TIFF, JPEG, ECW, etc.); if needed conversion to another raster format (poison, jpeg, etc) and send it to the client.
Next to WCS, to display a raster image to a local Geoide, you can also use a remote WMS Tomcat. Tomcat is the servlet container, i.e. the Java environment that http requests from a client passes to the application servlet and sends the response of the application back to the client. Tomcat can also be used to dynamically create HTML pages based on data in a database JDBC (Java Server Pages, JSP). Similar technologies such as ASP (Internet Information Server) or PHP (Apache) can be used as well.
Deegree, WMS
Deegree is an open source system written in Java that implements the OpenGIS specifications for cooperation between different GIS systems. In addition to the WFS and WCS services, Deegree also includes a Web Map Service (WMS) and Catalog Service for the Web (SW-C). An advantage of using the Deegree WFS and WCS-service is that clients other than the Geoide client can also use the same services which exchange with other GIS applications such organizations.
Configuration Files
Geoide uses XML for the configuration of the system. This entry contains the following components:
- Client layout and functionality (GIClientConfig.xml): Uses buttons coupled with functionality, layout and color scheme of the various client components;
- Maps (GIContext.xml): Legend per Map format, serving client;
- Geoide server capabilities (geoide.xml): List of available map layers or WMS and WFS data sets.
- Legend Symbology (SLD.xml): Rules for classification and use of symbols for each legend unit;
- Data Sources in vector format;
- WCS: data sources in raster/grid format.
Integration with other applications
Geoide can easily be integrated with other applications. A link can be made within the client and the server components of Geoide. As for the client to another (administrative) application example using an HTTP request (URL) call with a map image is zoomed to a specified object. It is also possible to integrate the Geoide client in a Windows application using the API of the Flash plug-in. Link to the server components is also possible using the http protocol. The WMS and WFS are fully OpenGIS-compliant. The Geoide-servlet supports a similar protocol.
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