Introducing the publish/subscriber pattern

- Now let's talk about the publish/subscriber pattern…or simply, Pub/Sub.…It's one of the more unique patterns we'll cover…in this course in that it doesn't deal with the creation…of objects or modifying their behavior.…Instead it deals with sending and receiving commands…to those objects.…The problem here is simple.…When we build systems the components have to link…to one another.…The general way of doing this is hard coding connections…between the components.…A calls B, which calls C.…This all works out well until you need to add…components D and E.…You end up with more and more connections…which becomes impossible to manage.…

We need a way to auto wire these components…without explicitly wiring them.…Luckily there's a pattern for that, Pub/Sub.…The concept is simple.…You have some shared channel or communication bus…where publishers send their messages.…Then you have a series of subscribers that are listening…to that channel for messages they care about.…When they detect messages that fit their requirements,…