TransformInstance

The Web Bean is a container for one or more Transform objects, and it must specify at run-time which Transform from its collection it wishes to use to perform data rendering.  When a Web Bean calls the transform() method, it specifies which Transform object it wishes to use by the TransformInstance key.

A TransformInstance object manages a transform and its associated MarkupOutput object.  Each TransformInstance is built to correspond to exactly one transform. Thus it can have a 'key’ set which allows it to be differentiated from all other TransformInstances by its unique name. This enables the caller to determine which transform is the default one and associate names for multiple transforms. By simply calling the transform method with no parameters, the default transform is automatically selected.

The advantage of using the TransformInstance key is that it enables multiple transforms to be applied, each uniquely identified by the key.