With the JavaBeansTM Activation Framework standard extension, developers
who use JavaTM technology can take advantage of standard services to
determine the type of an arbitrary piece of data, encapsulate access to
it, discover the operations available on it, and to instantiate the
appropriate bean to perform said operation(s). For example, if a browser
obtained a JPEG image, this framework would enable the browser to identify
that stream of data as an JPEG image, and from that type, the browser
could locate and instantiate an object that could manipulate, or view that
image.

WWW: http://java.sun.com/products/javabeans/jaf/