A factory is an object that creates instances or related types of objects. An abstract factory provides the interface that factory objects implement, as well as a method return a concrete factory implementation. For example, jETIA contains an Abstract DAO Factory that defines abstract methods to get different types of data access objects, and a static method to obtain a concrete instance of a DAO Factory.

In the abstract factory pattern as described in "Design Patterns", the Abstract Factory's static method to obtain a concrete factory instance would take a parameter identifying the type of concrete factory to return, and instantiate the appropriate sub-class of itself to satisfy the request. This hard coded knowledge of the available types of concrete factories makes it difficult to supply new types of factories later.

The Abstract Anonymous Factory is an adaptation of the abstract factory pattern that takes advantage of the anonymous class loading abilities of the Java runtime environment. Instead of explicitly telling the Abstract Factory about each type of Factory, the Abstract Anonymous Factory reads information about the types of concrete factories from a configuration file. The anonymous abstract factory then asks the runtime environment to find the class by name, and instantiate it.

Using this method, to add support for a new type of factory, the developer must implement the objects that are created by the concrete factory, create a new concrete subclass of the abstract anonymous factory, and modify a configuration file that is read dynamically at runtime. There is no need to recompile any of the code to deploy a new factory.

To help illustrate this concept, consider the sequence diagram shown the figure below. It depicts the sequence of events that occur when an application needs to use a Widget. In order to support a wide variety of widgets, an abstract anonymous widget factory is used. As you can see, the client obtains a concrete widget factory from the abstract anonymous widget factory. The configuration file is read to determine what types of widget factories are available, and in this instance, since no particular type is specified, the name of the default widget factory to use.

This is why the factory is referred to as "anonymous." Neither the client application nor the abstract factory has any advanced knowledge of the type of factory to instantiate. Since the concrete widget factory implements a known interface, it can be instantiated as a generic Object instance, and then cast to the appropriate interface type.