First of all, I suggest you watch this video.
It’ll explain a lot why webhooks are pretty fabulous. I’ve been trying to implement them recently in one of my own projects. I want a way to take a subscription payment for a web-service. The payment provider I have chosen is Recurly. This service has a payment page, very much like PayPal and special tools focused on management of subscriptions. Its pretty slick stuff. This was the first time that i’d encountered webhooks. After they subscribe to my service, their server sends a _POST request back to a my server, loaded full of xml related to the actions performed.
The one I’m looking for is ‘They paid and its all gravy’. This means i can activate their subscription.
At some point they might stop paying. At this point (any point in the future) the Recurly service will fire off another webhook at my server, letting me know that its not gravy. Behind the scenes, their account is automagically canceled.
The idea behind webhooks as explained in the video is a nice and simple one. So simple in fact that people have trouble understanding it. It allows the web to plug into other parts of the web. It allows completely seperate services and ideas to talk to each other, in a timely and smart manner.
Overall, its gravy.