Current Slide

Reactivity

• If a program’s environment is guaranteed to be fixed, the program need never worry about its own success or failure – program just executes blindly
• Example of fixed environment: compiler
• The real world is not like that: things change, information is incomplete. Many (most?) interesting environments are dynamic
• Software is hard to build for dynamic domains: program must take into account possibility of failure – ask itself whether it is worth executing!
• A reactive system is one that maintains an ongoing interaction with its environment, and responds to changes that occur in it (in time for the response to be useful)