In the Jabber
open-source instant messaging
system, the list of users that a particular user communicates with and receives presence
from or sends presence
to. The equivalent of a "buddy list
" or "contact list
" in other instant messaging
A roster is composed of zero or more roster items (<item/> elements), which contain the Jabber ID and optional nickname of a user, as well as an indication whether the current user sends presence to that user, receives presence from that user, or both. (This is also known as the subscription status.) Each roster item may also belong to one or more groups, which are indicated by <group/> elements underneath the <item/> element.
A Jabber client queries or sets its roster by using an Info/Query message with the jabber:iq:roster namespace.