Per-Entity Metadata Working Group

[Scott Koranda <>]

> I realized I didn't reply to the list when I wrote this.
> I setup Cloudfront as a caching CDN for the beta mdq server. Details
> in the forwarded message below, along with my latency figures.
> 
> 
> ---------- Forwarded message ----------
> From: Patrick Radtke 
> <>
> Date: Fri, Aug 26, 2016 at 3:57 PM
> Subject: Re: [Per-Entity] Latency figures for CDNs
> To: David Walker 
> <>
> 
> 
> On Fri, Aug 26, 2016 at 1:56 PM, David Walker 
> <>
>  wrote:
> > Getting back to Nick's original question, I guess I am concerned about the
> > latency times for 12KB objects (~0.4 secs in the US), unless we think
> > InCommon sites have much better connectivity than Frost and Sullivan's
> > average (and that the predominant latency factor is the last-mile 
> > network).
> >
> > This, of course, brings us back to Chris's admonition that we focus on
> > business needs.  What delay is acceptable when an IdP or SP needs to
> > retrieve the metadata for some other SP or IdP?  0.4 seconds sounds pretty
> > long to me, but it is a rare event, we think.
> 
> I setup Cloudfront (US, Canada and Europe locations) to be a caching
> proxy for the beta MDQ server.
> A cache miss in the edge location closest to you will result in a
> query going to the MDQ server. Cloud front will cache the result for
> an hour.
> You can test it by using http://drhqoesel6yr5.cloudfront.net/ in place
> of http://mdq-beta.incommon.org/
> 
> Using curl to do the timing
> 
> curl -o /dev/null -s -w \
> %{time_connect}:%{time_starttransfer}:%{time_total} \
> http://drhqoesel6yr5.cloudfront.net/global/entities/https%3A%2F%2Ffm.incommon.org%2Fsp
> 
> 
> I get, for a cache hit,
> 10-20 ms from an EC2 instance
> 33-50 ms from home
> cache misses seemed to add 1 second.
> 
> If I hit the MDQ beta server directly I get
> 10-30 ms from EC2 instance (this surprised me)
> 175-200 ms from home.
> 
> I'd be curious to see what the variance is for people on this list.
> Your first curl will be likely be a cache miss in the CDN.
> 

Thanks Patrick. This is quite interesting.

After filling the cache I see 13ms from the LIGO data center
on the campus of the University of Wisconsin-Milwaukee. 

I see 9 ms from the LIGO data center on the campus of Caltech.

I see 54 ms from the LIGO data center at the Albert Einstein
Institute on the campus of the University of Hannover,
Germany.

From home I see 17ms.

(all time_total).

Scott K