История изменений

Servers will usually have some timeout value beyond which they will
no longer maintain an inactive connection.  Proxy servers might make
this a higher value since it is likely that the client will be making
more connections through the same proxy server.  The use of
persistent connections places no requirements on the length (or
existence) of this timeout for either the client or the server.

A client or server that wishes to time out SHOULD issue a graceful
close on the connection.  Implementations SHOULD constantly monitor
open connections for a received closure signal and respond to it as
appropriate, since prompt closure of both sides of a connection
enables allocated system resources to be reclaimed.