Parent proxies are non-transparent HTTP proxies used behind PNS. Two things have to be set in order to use parent proxies. First, select a router which makes the proxy connect to the parent proxy, this can be either InbandRouter() or DirectedRouter(). Second, set the parent_proxy and parent_proxy_port attributes in the HttpProxy class. Setting these attributes results in proxy requests to be emitted to the target server both in transparent and non-transparent mode.

The parent proxy attributes can be set both in the configuration phase (e.g.: config() event), or later on a per-request basis. This is possible because the proxy re-connects.

class MyHttp(HttpProxy):
        def config(self):
                HttpProxy.config(self)
                self.parent_proxy = "proxy.example.com"
                self.parent_proxy_port = 3128

def instance():
        Service("http", MyHttp, router=InbandRouter())
        Listener(SockAddrInet('10.0.0.1', 80), "http")