Return a sequence of available zoom levels for a named layer.
Return a sequence of available zoom levels for a named layer.
This function should be re-implemented by AttributeStore subclasses so that catalogs with large numbers of layers can be queried efficiently.
The directory of the base catalog
Return a map with layer names and the list of available zoom levels for each.
Return a map with layer names and the list of available zoom levels for each.
This function should be re-implemented by AttributeStore subclasses so that catalogs with large numbers of layers can be queried efficiently.
Stores and retrieves layer attributes from the file system.