Odd but Handy URLs

Organization Link Purpose
Apple http://captive.apple.com/ non-SSL ProbeURL for WiFi hand-shaking. Replaces success.html.
Google http://www.google.com/ncr force plain English site (“no country redirect”)
IANA http://www.example.com official domain for examples in documents
IANA http://www.example.org official domain for examples in documents

How to fix “SuccessSuccess” Wi-Fi issue on MacOS X Mavericks temporally

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SpaceX Launch Begins Era of Space-Based ADS-B Tracking

The big news from the SpaceX launch of 10 Aireon Iridium 2G “Next” satellites is that ADS-B was also included on each satellite.

ADS-B is used for tracking and sending ATC digital information to airplanes. The FAA has mandated that almost all aircraft will install ADS-B transceivers before 2020, at a cost of $5,000 to $1 million per airplane, plus downtime.

Since there’s 150,000 registered US aircraft and thousands of foreign airliners, that just isn’t going to happen with the existing number of Mx shops and remaining 1,080 days. :)

These are fairly large satellites at 860 kg each:




SpaceX Launch Begins Era of Space-Based ADS-B Tracking
Iridium-1 Hosted Webcast
Layman HN Commentary
W: Automatic dependent surveillance – broadcast
faa.gov: ADS-B Frequently Asked Questions (FAQs)
avweb.com: New Satellites Promise Better ATC Coverage
gpsworld.com: Clocks fail on some Galileo satellites, backups working

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Perl and Monotonic Time Functions

Perl on Linux supports the POSIX C clock_gettime() function to get the monotonic time (always increasing system time, except for variable overflow) values:

Comparing monotonic time values:

  • avoid problems with leap seconds going backwards in time by NTP, but can “warp”
  • avoid problems with VM time going backwards
  • can only be used locally, not compared across machines
  • can rollover on variable overflow

Disadvantages of clock_gettime() over time/gmtime:

  • rollover requires awareness and calculation
  • not supported on Mac OS X and buggy before RHEL 5.3
  • relative time, not actual time, so cannot be displayed for humans
  • for most programs, requires code change and re-QA
  • dichotomy still exists between system and database time
use strict;
use diagnostics;

use Time::HiRes qw(clock_gettime CLOCK_REALTIME CLOCK_MONOTONIC);

   my $realtime = clock_gettime(CLOCK_REALTIME);

   my $mono = clock_gettime(CLOCK_MONOTONIC);

   print "realtime = $realtime, monotonic = $mono\n";
$ perl /tmp/clock.pl
realtime = 1483451061.64625, monotonic = 4536159.37919642

Perl – Time::HiRes
clock_gettime(3) – Linux man page
Erlang – Postscript: Time Goes On
lwn.net: The leap second of doom
SO: CLOCK_MONOTONIC Max value
SO: How do I get monotonic time durations in python?
SO: Linux clock_gettime(CLOCK_MONOTONIC) strange non-monotonic behavior
SO: Is CLOCK_MONOTONIC process (or thread) specific?
How the NYE leap second clocked Cloudflare – and how a single character fixed it
Time::Local

Posted in API Programming, Linux, Open Source, Perl, Tech | Leave a comment

eBay Bucks Base Earnings Now 1%

PSA:

“Changes to eBay Bucks Rewards Program starting January 1, 2017
Effective January 1, 2017 the Base earnings are changing from 2% to 1%.”

Guess I’ll be advising sellers to wait for 8% or 10% eBay Bucks days.



Last time I’ll see one of those.

Basic Economy Fares Don’t Lower Ticket Prices, They Increase Ticket Prices
The Champions of the 401(k) Lament the Revolution They Started

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Microservices: Java MicroProfile Links

Java DukeFrom the MicroProfile FAQ:

“The MicroProfile is a baseline platform definition that optimizes Enterprise Java for a microservices architecture and delivers application portability across multiple MicroProfile runtimes.

The initially planned baseline is JAX-RS + CDI + JSON-P, with the intent of community having an active role in the MicroProfile definition and roadmap.”

Looks more like a a REST bundle to me that avoids fixing Java’s inherent flaws:

  1. long GC pauses (seconds)
  2. bloated memory consumption (GBs)
  3. slow start-up time (seconds)
  4. crashes from exceeding pre-configured heap size
  5. licence confusion – is it Apache v2? EPL? “Copyrights are inconsistent at the moment”? what does Oracle say?

microprofile.io: Home, FAQ
theregister.co.uk: MicroServices-friendly Java lands on Eclipse
eclipse.org: Eclipse MicroProfile

Posted in API Programming, Business, Cloud, GC Pauses, Java, Linux, Microservices, Open Source, Oracle, REST API Programming, Tech | Leave a comment