Accessing form data from custom RuleAlgorithm implementation

The calculate method of the RuleAlgorithm interface is passed an array of the parameters, provided within the AttrValue tag of the OIR e.g. <Attr id="SomeAttribute"/>. While  RuleConfigurableTypeAttributes.properties can be configured, one is still typically limited as to what one can list there.

I would think there would be some APIs (e.g. action bean) used by the form submission framework to call the RuleAlgorithm implementation that can also be called directly from the RuleAlgorithm implementation to access the form data. Any ideas?

Environment: PDMLink 11.2 M010