Programming Jabber

The <rate/> Tag

The <rate/> tag affords us a sort of connection throttle by allowing us to monitor the rate at which incoming connections are made and to put a hold on further connections if the rate is reached.

The rate is calculated to be a number of connection attempts—from a single IP address—within a certain amount of time. We can see these two components of the rate formula as attributes of the <rate/> tag itself:

<rate points="5" time="25"/>

This means acceptance of incoming connections from an individual IP address will be stopped if more than five connection attempts (points) are made in the space of 25 seconds (time).

The “rating” (the throttling of connection attempts) will be restored at the end of the period defined (25 seconds in this case).

The effect of a <rate/> tag in this io section is serverwide; all socket connections (for example, those of c2s and s2s) can be rate-limited. If there is no explicit <rate/> specification in a particular service that listens on a socket for connections, then the specification in this io section is used. If no <rate/> tag is specified in this io section, then the server defaults are used—these are actually the same as what’s explicitly specified here.