Pyramid is a WSGI application framework that primarily follows a request-response mechanism. However, if you need to work with events you can still use them. It comes with some default event types that are emitted implicitely by Pyramid as long as you have a subscriber for them. For most applications the default event types are enough, but what if you want to write your custom event type and emit it explicitly from your code? It turns out that the application registry that Pyramid uses by default comes with a handy notify method. Pyramid uses this method internally  for its default events. Here is how you would take advantage of it:

from import subscriber

class MyCustomEventType(object):
    def __init__(self, msg):
        self.msg = msg

def my_subscriber(event):

def my_view(request):
    request.registry.notify(MyCustomEventType("Here it comes"))
    return {}

When running the application, every time a request goes through my_view, an event with a message is emitted, in this case, “Here it comes”. The subscriber then handles the event by printing the message, but it could do anything you want.

Notice that I’m using a decorator to hook my_subscriber. In order for the decorator to work you have to make sure you call the scan method when configuring the application.

Be aware though, that all these events are synchronous because Pyramid is primarily a request-response framework, all the events emitted block until the subscribers are done. If you want non-blocking events in Pyramid you could spawn a process from the subscriber or come with some other solution.

But the events in Pyramid are just another functionality that it offers. Pyramid is not a event-oriented framework, if you want to go all the way with async events you should look into Twisted or Tornado.