A Analysis works directly on the structure of the RFG, thus they are implemented as Actions. All Analyses derive from the abstract class RFG_Analysis and have to overwrite only the method "Execute_Analysis", all other parts are mostly done automagically.
Parameters given by the paramter dialog (see Analysis-Master, the Section called Analysis-Master in Chapter 5) can be read from the Parameter Pot. Then the Analysis can modify the RFG without knowing about the mechanisms of the observers, which modify the model of OpenCAGE itself.