what is the architecture of a servlets package
The javax.servlet package provides interfaces and classes for writing servlets. The Servlet Interface
The central abstraction in the Servlet API is the Servlet interface. All servlets implement this interface, either directly or, more commonly, by extending a class that implements it such as HttpServlet.
Servlets | GenericServlet | HTTPServlet | MyServlet
The Servlet interface declares, but does not implement, methods that manage the servlet and its communications with clients. Servlet writers provide some or all of these methods when developing a servlet.