Keep-Alive

O cabeçalho Keep-Alive permite que o remetente indique como a conexão deve ser usada, para definir um tempo limite e um máximo de requisições.

O Connection cabeçalho precisa ser definido como "keep-alive" para isso funcionar , Connection e Keep-Alive são ignorados em conexões HTTP/2; Gerenciamento de conexões são feitos por outros mecanismos.

Tipo de cabeçalho General header
Forbidden header name sim

Sintaxe

Keep-Alive: parametros

Diretivas

parâmetros
Uma vírgula separa a lista de parâmetros, Cada consiste de um identificador e um valor separado pelo sinal de igualdade ('='). São possíveis os seguintes identificadores:
  • timeout: indicando a quantidade mínima de tempo que uma conexão deve ser mantida aberta (em segundos). Observe que os tempos limite maiores que o tempo limite do TCP podem ser ignorados se nenhuma mensagem TCP keep-alive estiver definida na camada de transporte.
  • max: indicando o número máximo de pedidos que podem ser enviados nesta conexão antes de fechá-lo. Menor que 0, este valor será ignorado por conexões non-pipelined, pois outra requisição será enviada na próxima resposta. Um HTTP pipeline pode usar isso para limitar o pipelining. 

Exemplos

Uma resposta content o cabeçalho Keep-Alive:

HTTP/1.1 200 OK
Connection: Keep-Alive
Content-Encoding: gzip
Content-Type: text/html; charset=utf-8
Date: Thu, 11 Aug 2016 15:23:13 GMT
Keep-Alive: timeout=5, max=1000
Last-Modified: Mon, 25 Jul 2016 04:32:39 GMT
Server: Apache

(body)

Especificações

Specification Title
HyperText Transport Protocol Keep-Alive Header The Keep-Alive Header (Experimental specification)
RFC 7230, appendix A.1.2: Keep-Alive Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing

Compatibilidade dos navegadores

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Keep-AliveChrome Full support YesEdge Full support 12Firefox Full support YesIE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android Full support YesOpera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support

Veja também

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