Hi,
HttpServlet is abstract class because is a *stub* -
a class that implements the pertinent interfaces
with methods that do NOTHING-.
Developers can subclasse the stub, overriding only
those methods that are important to their application.
<!-- After E Gamma an Adapter (Design
patterns??) -->
This construct is fine, because it makes easy to create a subclass
(your class) that reacts to *only* the relevant events that are
important to your application.
gruesse,
ser