Java Reference
In-Depth Information
catch
(IOException ioe) { ioe.printStackTrace(); }
dataWindow.redraw();
}
}
15.6.4
Test
The test cases of the third prototype require installing the GIS application
server on a desktop PC that runs a web server and starting a web browser on
another networked computer. The test should verify that the applet is down-
loaded from the web server and started by the web browser correctly and
that the applet and the application server communicate correctly. The
following steps illustrate how to install the GIS.
■
On the server side:
-
Create the GIS database and insert the references to the available
thematic databases and tables.
-
Create the ODBC logical links to the GIS database and to the thematic
databases.
-
Copy the byte code of class
GisApplet
and the HTML file shown in
Figure 15.13 in the home directory of the web server or in one of its
subdirectories.
-
Start the application server, i.e. run class
GisServer
.
On the client side:
■
-
From a web browser connect to the HTML file that embeds the GIS
applet.
-
Once the applet has been loaded in the web browser, its graphical inter-
face should appear as shown in Figure 15.5.
15.7
■
Extension
In Section 15.6.1 we assumed that the GIS manager is able to generate query
tables within the thematic databases in order to circumscribe the data that
can be linked to a cartographic map. Prototype 2 allows the user to associate
geographic entities with single records of a query table. A more flexible
solution would allow the user to associate an entity with the SQL query that
generates a record from a set of tables.
The GIS applet allows the user to select only one geographic entity at a
time and to browse the associated data. When entities belonging to different
layers overlap, it would be nice to visualize the union of the data associated
with those entities.
15.8
■
Assessment
This case study has shown how to develop a set of tools for building
geographic information systems: a map editor, a data-map linker and a
map-based data browser.
