The UrlDefinitionsFactory is the default implementation of DefinitionsFactory.
The DefinitionsReader interfaces reads a source (usually an URL) to return a map of raw (i.e. with their inheritance not resolved) definitions. The default implementation, DigesterDefinitionsReader reads from usual Tiles XML definition files using Jakarta Commons Digester.
If you need to read definitions from other kind of sources, this is the item to configure.
The LocaleResolver interface resolves the current locale requested by the user. The default implementation, DefaultLocaleResolver takes the current locale from a session-scoped Locale object under the org.apache.tiles.LOCALE key. If it is not found, the default locale of the request will be taken.
If you want to read the current locale in other ways, this is the item to configure.