5.2.3.4 Locating Factories in Another Domain

Typically, a FactoryFinder returns references to factory objects that are in the same domain as the FactoryFinder itself. However, it is possible to return references to factory objects in domains other than the domain in which a FactoryFinder exists. This can occur if a FactoryFinder contains information about factories that are resident in another domain (see the following figure). A FactoryFinder finds out about these interdomain factory objects through configuration information that describes the location of these other factory objects.

When a FactoryFinder receives a request to locate a factory object, it must first determine if a reference to a factory object that meets the specified criteria exists. If there is registration information for a factory object that matches the criteria, the FactoryFinder must then determine if the factory object is local to the current domain or needs to be imported from another domain. If the factory object is from the local domain, the FactoryFinder returns the reference to the factory object to the client.

Figure 5-3 Inter-Domain FactoryFinder Interaction

If, on the other hand, the information indicates that the actual factory object is from another domain, the FactoryFinder delegates the request to an interdomain FactoryFinder in the appropriate domain. As a result, only a FactoryFinder in the same domain as the factory object will contain an actual reference to the factory object. The interdomain FactoryFinder is responsible for returning the reference of the factory object to the local FactoryFinder, which subsequently returns it to the client.