Wiring

Learn about wiring

wiring

for a system to work, each component’s required interfaces have to be provided by another’s interface

wiring stage 1

deciding which component will provide which required interfaces

wiring stage 2

performing the binding to connect the chosen components together

benefits of dependency injection 1

late binding - services can be swapped with others

benefits of dependency injection 2

extensibility - code can be extended and reused in ways not explicitly planned for

benefits of dependency injection 3

code can be developed in parallel

benefits of dependency injection 4

classes with clearly defined responsibility are easier to maintain

cup and ball diagrams

full circle provides, half circle requires

wiring question 1

when does it occur? at installation? at start up? dynamically through lifetime?

wiring question 2

how is the wiring specified? implicitly? explicitly as code? or explicitly as workflow?

wiring at installation pros

detect anomalies, find missing components

wiring at installation cons

not very extensible and not very robust

wiring at startup pros

find issues before any user touches the system, clear behaviour, extensible when system restarts

wiring at startup con

subject to binding failures

wiring dynamically notes

more flexible and extensible, but more complex

interface compatibility option 1

name based - interfaces have the same name

interface compatibility option 2

structural type - interfaces respond to the same operations or messages