org.geotools.factory
Interface OptionalFactory

All Superinterfaces:

Factory

All Known Implementing Classes:

AuthorityBackedFactory, DeferredAuthorityFactory

public interface OptionalFactory

extends Factory

An optional factory that may not be available in all configurations.

Such factories often need some external resources. For example the default EPSG factory need a MS-Access database installed on the client machine. This database is not bundle in Geotools distribution; if the user have not installed it, the factory can't work.

This interface is not a manager for automatic download of external resources. It is just a way to tell to FactoryFinder that this factory exists, but can't do its job for whatever reasons (usually a missing resource that the user shall download and install himself), so has to choose an other factory. In other words, the interface is used as a filter, nothing else. The process is as follows:

• When FactoryRegistry.getServiceProvider(java.lang.Class, javax.imageio.spi.ServiceRegistry.Filter, org.geotools.factory.Hints, org.geotools.factory.Hints.Key) is invoked, it starts to iterate over all registered factories. If an ordering is set, it is taken in account for the iteration order.
• If no suitable factory was found before the iterator reachs this optional factory, then isReady() is invoked. If it returns , then this optional factory is processed like any other factories. Otherwise it is ignored.

NOTE: is not designed for factories with intermittent state (i.e. return value of isReady() varying in an unpredictable way). The behavior is undetermined if the state changes with time.

Version:

$Id: OptionalFactory.java 17672 2006-01-19 00:25:55Z desruisseaux $

Author:

Martin Desruisseaux

Method Summary

boolean

isReady() Returns if this factory is ready for use.

Methods inherited from interface org.geotools.factory.Factory

getImplementationHints

Method Detail

isReady

public boolean isReady()

Returns if this factory is ready for use. An optional factory may returns for now but returns later. However, the converse is not recommended.