Inversion of Control

Final one GAH

control inversion

control doesn’t follow the call order, different parts of the code receive control at unpredictable moments

characteristics of control inversion 1

can’t walk through the code because logical flow is uncertain

characteristics of control inversion 2

need to ensure all paths are correct when debugging

why control inversion?

allows for more sophisticated programming constructions

example of inverted control 1

callbacks - allow server to interact with client

example of inverted control 2

factories - components that create others

example of inverted control 3

dependency injection - complex factories that encapsulate dependencies between sets of components

example of inverted control 4

extension via code fragments - move code around the network

challenges with callbacks

concurrency - client has to respond to server in the middle of a call, which means it constantly needs to be listening and responding

dependency injection design pattern

encapsulate complex construction and wiring, the inversion of control comes as the DI component contains logic that’s been removed from the clients and refactored

variations of dependency injection

method, interface, setter and constructor dependency

issue to bear in mind for all the systems 1

different code bases

issue to bear in mind for all the systems 2

different authorities

issue to bear in mind for all the systems 3

different permissions

issue to bear in mind for all the systems 4

different levels of understanding of how the overall system fits together