What logic defines which method(s) are invoked when an implementation class is called?

See Writing Components
Answer below from the nabble user mailing list:

I don't understand how Implementation classes work (in UMO descriptors). While the class itself is registered in the XML configuration file, I don't see any mapping for the class methods with their signatures. How does the Mule engine know how to invoke these methods? The Hello World example works, but I am having trouble seeing any design patterns/restrictions to carry forward to my own UMO Components.

Hi,

It matches the payload (message) type with the methods available on your component. That is, if after transformations there is a method accepting this transformed message object it gets called.

Andrew

This uses reflection..
If you have multiple methods matching the criteria you will receive this error at runtime: Found too many possible entry points on: class

If you implement the Callable interface then the logic will always invoke the method onCall().