Description
A web server can only serve a limited number of concurrent requests. QoS is used to ensure that important resources stay available under high server load. mod_qos is used to reject requests to unimportant resources while granting access to more important applications. It is also possible to disable access restrictions, for example, for requests to very important resources or for very important users.
Control mechanisms are available at the following levels:
- Request level control: mod_qos controls the number of concurrent requests to a name space (URL). It is used to define different priorities to different pages or applications within a web server.
- Connection level control: mod_qos controls the number of TCP connections to the web server. This helps limit the connections coming from a single client or from unknown networks, in order to reduce the maximum number of concurrent connections to a virtual server or to implement dynamic HTTP keep-alive settings.
- Bandwidth level control: throttles requests/responses to certain URL on the web server.
- Generic request line and header filter dropping suspicious request URLs or HTTP headers.
The module can be useful when used in a reverse proxy in order to divide up resources to different webserver.
Read more about this topic: Mod Qos
Famous quotes containing the word description:
“Everything to which we concede existence is a posit from the standpoint of a description of the theory-building process, and simultaneously real from the standpoint of the theory that is being built. Nor let us look down on the standpoint of the theory as make-believe; for we can never do better than occupy the standpoint of some theory or other, the best we can muster at the time.”
—Willard Van Orman Quine (b. 1908)
“God damnit, why must all those journalists be such sticklers for detail? Why, they’d hold you to an accurate description of the first time you ever made love, expecting you to remember the color of the room and the shape of the windows.”
—Lyndon Baines Johnson (1908–1973)
“Do not require a description of the countries towards which you sail. The description does not describe them to you, and to- morrow you arrive there, and know them by inhabiting them.”
—Ralph Waldo Emerson (1803–1882)