Programming Jabber

The <karma/> Tag

Like the <rate/> tag, <karma/> is used to control connectivity. Whereas rating helps control the number of connections, karma allows us to control the data flow rate per connection once a connection has been made.

The concept of karma is straightforward; each socket has a karma value associated with it. We can understand it better if we think of it as each entity (connecting through a socket) having a karma value. The higher the value—the more karma—an entity has, the more data it is allowed to send through the socket. So as rating is a throttle for connections, so karma is a throttle for data throughput.

There are certain settings that allow us to fine-tune our throughput throttle. Table 4-6 lists these settings, along with the values explicitly set in each of the c2s and s2s component sections in our jabber.xml file. Notice how the settings for the Server (to Server) Connections component are considerably higher than those for the Client (to Server) Connections—this is based on the assumption that server-to-server traffic will be greater than client-to-server on a socket-by-socket basis.

Table 4-6. Settings for karma control, with c2s and s2s values

Setting	c2s values	s2s values	Description
<init/>	10	50	The initial value for karma on a new socket.
<max/>	10	50	The maximum karma value that can be attained by a socket.
<inc/>	1	4	By how much the karma value is incremented (over time).
<dec/>	1	1	By how much the karma value ...