Compare Revisions

Connection management in HTTP/1.x

Change Revisions

Revision 1120485:

Revision 1120485 by bunnybooboo on September 18, 2016 at 6:52:20 AM PDT

Revision 1120501:

Revision 1120501 by bunnybooboo on September 18, 2016 at 7:08:01 AM PDT

Title:

Connection management in HTTP/1.x

Slug:

Web/HTTP/Connection_management_in_HTTP_1.x

Tags:

"Guide" "HTTP" "Performance" "WebMechanics" "Performance"

Comment:

editorial review of short-lived

peristent connections editorial review

Content:

	Revision 1120485			Revision 1120501
n	54	Short-lived connections have two major drawbacks: the time	n	54	Short-lived connections have two major hitches: the time ta
	>	to establish a new connection is significant, and the performance		>	ken to establish a new connection is significant, and performance
	>	of the underlying TCP connection gets better only when this conn		>	of the underlying TCP connection gets better only when this conn
	>	ection has been in use for some time (warm connection). To mitiga		>	ection has been in use for some time (warm connection). To ease t
	>	te this problem, even before HTTP/1.1, the concept of a <em>persi		>	hese problems, the concept of a <em>persistent connection</em> ha
	>	stent connection</em> has been crafted, sometimes called a <em>ke		>	s been designed, even prior to HTTP/1.1. Alternatively this may b
	>	ep-alive connection</em>.		>	e called a <em>keep-alive connection</em>.
n	57	A persistent connection is a connection that stays open for	n	57	A persistent connection is a one which remains open for a p
	>	some time and that can be reused for several requests, sparing t		>	eriod, and can be reused for several requests, saving the the nee
	>	he TCP handshake and making better use of the TCP performance cap		>	d for a new TCP handshake, and utilizing TCP's performance enhanc
	>	abilities. The connection will not stay open forever: idle connec		>	ing capabilities. This connection will not stay open forever: idl
	>	tions are closed after some time (a server may use the {{HTTPHead		>	e connections are closed after some time (a server may use the {{
	>	er("Keep-Alive")}} header to give a minimum amount of time they s		>	HTTPHeader("Keep-Alive")}} header to specify a minimum time the c
	>	hould be kept open).		>	onnection should be kept open).
n	60	Persistent connections also have drawbacks; even when idlin	n	60	Persistent connections also have drawbacks; even when idlin
	>	g they consume some server resources and under heavy load, {{glos		>	g they consume server resources, and under heavy load, {{glossary
	>	sary("DoS attack", "DoS attacks")}} can be conducted. In these ca		>	("DoS attack", "DoS attacks")}} can be conducted. In such cases,
	>	ses, using non-persistent connections, that are closed as soon as		>	using non-persistent connections, which are closed as soon as the
	>	they are idle, brings better performance.		>	y are idle, can provide better performance.
n	63	HTTP/1.0 connections are not persistent by default. Setting	n	63	HTTP/1.0 connections are not persistent by default. Setting
	>	{{HTTPHeader("Connection")}} to anything other than <code>close<		>	{{HTTPHeader("Connection")}} to anything other than <code>close<
	>	/code>, usually <code>retry-after</code> will make them persisten		>	/code>, usually <code>retry-after</code>, will make them persiste
	>	t.		>	nt.
t	66	On the other hand, on HTTP/1.1, they are persistent by defa	t	66	In HTTP/1.1, peristence is the default, and the header is n
	>	ult and the header is not needed (but often added so that it is t		>	o longer needed (but often added in case of a fallback to HTTP/1.
	>	aken into account in case of a fallback to HTTP/1.0).		>	0).

Back to History