Design Pattern for Task Notification System

Question

I am looking a good design pattern that takes a combination of a Observer Design Pattern and Command Design Pattern.
Observer Design Pattern:

• Subject - ISystem
• ConcreteSubject - "Different Types of Systems"
• Observer - INotifier
• ConcreteObserver - "Different Types of Notifier's"

Command Design Pattern: Used to create a task. "Different Types of Task"
If anyone know of any good resource I can use or have done something related to what I am looking for please share?