You can save the map with data, or save it
as a theme only containing references to the raw map data.
Map Theme Only
A theme has basically to do with the look
and feel of the map and provides you with full control over how
map data is displayed. A map theme allows you to decide what is
displayed, when, and how.
If a map is saved as theme only, the
application must have access to the map data sources. The
following prepared map data is saved:
- Uniform Resource Locators (URLs) or file names, pointers to map data sets (server, local directories, databases, …), and any specific parameter relevant to each data source (for example, the features selected or the area of selection within the data source).
- The number, name and hierarchy of layers.
- The look and feel of each layer (color, transparency, thickness for vector, …).
- The resolution collection to which a given map theme will apply (for example, see roads in white, thickness 3 at “street level”, but after a zoom out operation see the same roads in black, thickness 1 at “city level”, then zoom out again to make them disappear).
- The zoom level setting, if this has been defined by an Area of Interest, (see Managing areas of interest).
A use case for this implementation could be as an application
used to monitor traffic in a Web portal. The application
developed using JViews
Maps would load the latest traffic and street information at
launch time, from external Map Servers.
For more information about saving a map theme, see Saving a map.
Map Theme and Map Data
When you save the map theme and the map
data, the contents of the map file are the same as when you save
a map theme only, but instead of storing map data as a set of
URLs or pointers, the data is copied locally. This provides a
faster loading time, especially for raster data, and allows a map
to be displayed even if the original "source data" is not
accessible anymore.
However, some operations on the map such
as a change in coordinate system might need this source data to
ensure proper reprojection without loss of precision. If source
data is not available, embedded map elements are reprojected
without reading them back from the original data source.
A use case for this implementation could be if the application
developed using JViews
Maps is used to monitor the position of firemen in a building.
The firemen would probably have poor or no connectivity to a
server, so would need map data locally. Any available bandwidth
could be used to update the position of the individual firemen
in the building during an intervention.
For more information about saving a map theme and map data, see Saving a map.