public class PresenceSubscribeHandler extends BasicModule implements ChannelHandler<org.xmpp.packet.Presence>Implements the presence protocol. Clients use this protocol to update presence and roster information.
The handler must properly detect the presence type, update the user's roster, and inform presence subscribers of the session's updated presence status. Presence serves many purposes in Jabber so this handler will likely be the most complex of all handlers in the server.
There are four basic types of presence updates:
- Simple presence updates - addressed to the server (or to address), these updates are properly addressed by the server, and multicast to interested subscribers on the user's roster. An empty, missing, or "unavailable" type attribute indicates a simple update (there is no "available" type although it should be accepted by the server.
- Directed presence updates - addressed to particular jabber entities, these presence updates are properly addressed and directly delivered to the entity without broadcast to roster subscribers. Any update type is possible except those reserved for subscription requests.
- Subscription requests - these updates request presence subscription
status changes. Such requests always affect the roster. The server must:
- update the roster with the proper subscriber info
- push the roster changes to the user
- forward the update to the correct parties.
- XMPPServer probes - Provides a mechanism for servers to query the presence status of users on another server. This allows users to immediately know the presence status of users when they come online rather than way for a presence update broadcast from the other server or tracking them as they are received. Requires S2S capabilities.
WarningThere should be a way of determining whether a session has authorization to access this feature. I'm not sure it is a good idea to do authorization in each handler. It would be nice if the framework could assert authorization policies across channels.
- Iain Shigeoka
Nested Class Summary
Nested Classes Modifier and Type Class Description
PresenceSubscribeHandler.ChangeIndicate a state change.
Constructors Constructor Description
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description
getStateChange(RosterItem.SubType itemSubType, org.xmpp.packet.Presence.Type action, boolean isSending)Determine the changes to apply to the item, according to its subscription state.
initialize(XMPPServer server)Initializes the basic module.
process(org.xmpp.packet.Presence presence)Process an XMPP packet.
Methods inherited from class org.jivesoftware.openfire.container.BasicModule
destroy, getName, start, stop
public void process(org.xmpp.packet.Presence presence) throws PacketExceptionDescription copied from interface:
ChannelHandlerProcess an XMPP packet.
public static PresenceSubscribeHandler.Change getStateChange(RosterItem.SubType itemSubType, org.xmpp.packet.Presence.Type action, boolean isSending)Determine the changes to apply to the item, according to its subscription state. The method also turns the action and sending status into an integer code for easier processing (switch statements).
Code relies on states being in numerical order without skipping. In addition, the receive states must parallel the send states so that (send state X) + STATE_RECV_SUBSCRIBE == (receive state X) where X is subscribe, subscribed, etc.
itemSubType- The item to be updated
action- The new state change request
isSending- True if the roster owner of the item is sending the new state change request
- Change changes to apply to the item
public void initialize(XMPPServer server)Description copied from class:
Initializes the basic module.
Inheriting classes that choose to override this method MUST call this initialize() method before accessing BasicModule resources.