RE: Proxy Automatic Configuration files
RE: Proxy Automatic Configuration files
- Subject: RE: Proxy Automatic Configuration files
- From: Tommy Nguyen <email@hidden>
- Date: Fri, 6 Jun 2008 16:03:43 -0700
- Acceptlanguage: en-US
- Thread-topic: Proxy Automatic Configuration files
Hi Jeff, thanks much for the info. I was asking because the old Netscape Navigator doc that originally describes the PAC file format is a bit vague, but seems to hint that caching of whether a given proxy is down, is done (at least for a certain period of time):
----------------------
http://wp.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html
The Navigator will automatically retry a previously unresponsive proxy after 30 minutes, then after 1 hour from the previous try (always adding an extra 30 minutes).
If all proxies are down, and there was no DIRECT option specified, the Navigator will ask if proxies should be temporarily ignored, and direct connections attempted. The Navigator will ask if proxies should be retried after 20 minutes has passed (then the next time 40 minutes from the previous question, always adding 20 minutes).
----------------------
So my question is not so much about caching the entire proxy list, but more about caching the status of individual proxies that are down (some of which may or may not be in the proxy list). What is Apple's guidance on doing this (not recommended? recommended with certain timeout lengths? etc)?
Thanks,
Tommy
> -----Original Message-----
> From: macnetworkprog-bounces+tommy.nguyen=email@hidden
> [mailto:macnetworkprog-
> bounces+tommy.nguyen=email@hidden] On Behalf Of Jeff
> Jenkins
> Sent: Friday, June 06, 2008 2:36 PM
> To: Tommy Nguyen
> Cc: email@hidden
> Subject: Re: Proxy Automatic Configuration files
>
> There is no caching of the proxy list, since the PAC file could change
> and the proxy server's status could change as well.
>
> -- jrj
>
> On Jun 5, 2008, at 12:39 PM, Tommy Nguyen wrote:
>
> > The 10.5 SDK now supports processing of PAC files, however it's not
> > entirely clear what the correct behavior should be when proxies are
> > down.
> >
> > For example, say the OS returns 2 proxies: {ProxyA, ProxyB}. ProxyA
> > is down and takes a while for the connection attempt to timeout, but
> > we ultimately discover ProxyB is good, and use it. Should this
> > information be cached, and if so, for how long? For example, say
> > another thread is spawned that tries to make the same connection
> > attempt. Should that second thread already know that ProxyA is down
> > and just go straight to ProxyB (and if so, how long before new
> > threads try connecting with ProxyA again?) or should it *always*
> > retry the full proxy list for every new connection?
> >
> > Thanks,
> > Tommy
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