Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A keepalive is a message sent by one device to another to check that the link between the two is operating. A keepalive signal is often sent at predefined intervals, and plays an important role on the Internet. After a signal is sent, if no reply is received the link is assumed to ...Täielik kirjeldus
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A keepalive is a message sent by one device to another to check that the link between the two is operating. A keepalive signal is often sent at predefined intervals, and plays an important role on the Internet. After a signal is sent, if no reply is received the link is assumed to be down and future data will be routed via another path until the link is up again. Since the only purpose is to find links that don't work, keepalive messages tend to be short and not take much bandwidth. However, their precise format and usage terms depend on the communication protocol. Keepalive messages were not officially supported in HTTP 1.0. In HTTP 1.1 all connections are considered persistent, unless declared otherwise. However, the default keepalive timeout of Apache 2.0 httpd is as little as 15 seconds and for Apache 2.2 only 5 seconds. The advantage of a short timeout is the ability to deliver multiple components of a web page quickly while not tying up multiple server processes or threads for too long.