> -----Ursprüngliche Nachricht----- > Von: Jim Jagielski > Gesendet: Mittwoch, 13. Februar 2008 17:07 > An: dev@httpd.apache.org > Betreff: ping for http in mod_proxy > > I've started looking at adding "ping" support for > mod_proxy_http to complement whats in mod_proxy_ajp... > The idea is to send a simple OPTIONS * to the backend > and hope for a reply. > > The rub is that I've been working on 2 separate > implementations: one talks direct to the socket and the > other basically tries to do what ap_proxy_http_request() > and ap_proxy_http_process_response() does, as far > as using brigades, etc... The former is much further > along, btw.
We cannot use the socket approach since we need to be able to handle SSL backend connections and this requires the brigades - filters approach. > > In any case, both implementations can have what I can > envision as some "weird effects" as far as how they > should actually work in the real world. For example, > should it honor force-proxy-request-1.0 and/or > proxy-nokeepalive, and, if so, how does that affect I think the ping is of limited use for HTTP/1.0 / non keepalive requests. I see it mainly as a measure to avoid race conditions with keepalive connections that get closed just in the moment as the request is being sent. The only benefit I would see for HTTP/1.0 / non keepalive requests would be that a successful connect call (we always create a new connections in this case) does not guarantee us that you get *any* response (in a timely manner). This could be because the connect is queued up on the backend in the connection backlog or in an application specific request queue and will be never processed. > the subsequent "real" request... In other words, > it's not as clean as AJP which has a "real" ping. > And all this is wondering whether or not it's > really useful in the 1st place... > > So before I go any further, any comments or ideas > on whether is is even a Good Idea or not... I'm starting > to have 2nd thoughts :) > It is a good idea for certain purposes and I really appreciate that you work on this. This issue is still on my when-I-got-time-TODO list. If not done until then, maybe something for the hackathon to work on. Regards Rüdiger
