2 Map Visualization Concepts

This chapter explains concepts that you should be familiar with before using the map visualization component.

Some fundamental concepts include style, theme, base map, mapping metadata, and map.

• Styles define rendering properties for features that are associated with styles. For example, a text style determines how such a feature is labeled on a map, while a line style determines the rendition of a linear feature such as a road.

• A theme is a collection of features (entities with spatial and nonspatial attributes) that are associated with styles through the use of styling rules.

• A base map consists of one or more themes. (A base map should not have the same name as any theme.)

• Mapping metadata consists of a repository of styles, themes, and base maps stored in a database.

• A map is one of the components that the map visualization component creates in response to a map request. The map can be an image file, the object representation of an image file, or a URL referring to an image file.

• Overview of the Map Visualization Component
  When an application uses the map visualization component, it applies specific styles (such as colors and patterns) to specific themes (that is, collections of spatial features, such as cities, rivers, and highways) to render a map (such as a GIF image for display on a web page).
• Styles
  A style is a visual attribute that can be used to represent a spatial feature.
• Themes
  Theme is perhaps the most important concept in the map visualization component. A theme is a visual representation of a particular data layer.
• Maps
  A map can consist of a combination of elements and attributes.
• How a Map Is Generated
  When a map request arrives at the map visualization component server, the server picks a free renderer associated with the data source in the request.
• Cross-Schema Map Requests
  A database user can issue a map request specifying a theme that uses data associated with another database user, to select data from tables that the other data source user is authorized to access.
• Workspace Manager Support in the Map Visualization Component
  Workspace Manager is an Oracle Database feature that lets you version-enable one or more tables in the database.
• Map Visualization Component Metadata Views
  The mapping metadata describing base maps, themes, and styles is stored in the global tables SDO_MAPS_TABLE, SDO_THEMES_TABLE, and SDO_STYLES_TABLE, which are owned by MDSYS.
• Oracle Maps
  Oracle Maps is the name for a suite of technologies for developing high-performance interactive web-based mapping applications. It consists of components from both the server side and the client side.