06-20-2013
Parkinson's law: need expands to consume excess resources.
Companies like Akamai make a good living ensuring your static web hits are filled from relatively local cache servers.
Good architectural design has to deal with:
- having a soft saturation, so throughput goes up to saturation and then excess load is shedded in a least-lost-value basis, like newest clients lower in priority than older clients (deeper into transaction process).
- avoiding negative saturation behaviors like overloaded Ethernet, which actually slows down due to collisions creating lost time on wire. Positive saturation behavior means the higher the overload, the more efficient the process. Requests can be sorted to they have higher locality of reference. Sometimes, requests for the same file can be mbone multicast as one. Sorting by disk position means shorter seeks.
- flow control mechanisms allow services beyond capacity to be queued for eventual fulfillment, but service cancellation is quickly forearded to the server. The bad behaviors are thing like sending service requests every n seconds until a reply is received, consuming precious bandwidth and cluttering the server with cancelled, redundant, prior requests. Some routers can stifle keep-alive traffic, say from tcp connections of queued services, so they do not drag down net speed.
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LEARN ABOUT DEBIAN
convert::color::hsl
Convert::Color::HSL(3pm) User Contributed Perl Documentation Convert::Color::HSL(3pm)
NAME
"Convert::Color::HSL" - a color value represented as hue/saturation/lightness
SYNOPSIS
Directly:
use Convert::Color::HSL;
my $red = Convert::Color::HSL->new( 0, 1, 0.5 );
# Can also parse strings
my $pink = Convert::Color::HSL->new( '0,1,0.8' );
Via Convert::Color:
use Convert::Color;
my $cyan = Convert::Color->new( 'hsl:300,1,0.5' );
DESCRIPTION
Objects in this class represent a color in HSL space, as a set of three floating-point values. Hue is stored as a value in degrees, in the
range 0 to 360 (exclusive). Saturation and lightness are in the range 0 to 1.
CONSTRUCTOR
$color = Convert::Color::HSL->new( $hue, $saturation, $lightness )
Returns a new object to represent the set of values given. The hue should be in the range 0 to 360 (exclusive), and saturation and
lightness should be between 0 and 1. Values outside of these ranges will be clamped.
$color = Convert::Color::HSL->new( $string )
Parses $string for values, and construct a new object similar to the above three-argument form. The string should be in the form
hue,saturation,lightnes
containing the three floating-point values in decimal notation.
METHODS
$h = $color->hue
$s = $color->saturation
$v = $color->lightness
Accessors for the three components of the color.
( $hue, $saturation, $lightness ) = $color->hsl
Returns the individual hue, saturation and lightness components of the color value.
SEE ALSO
o Convert::Color - color space conversions
o Convert::Color::RGB - a color value represented as red/green/blue
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
perl v5.12.3 2011-06-15 Convert::Color::HSL(3pm)