The Kraken plugin allows users to log in to and communicate through other instant messaging services via their XMPP accounts. The gateway itself provides a number of "transports" to other protocols (AIM, ICQ, MSN, Yahoo, etc).
To help identify the differences between the plugin as a whole and the underlying interfaces to external protocols (AIM, ICQ, etc), we refer to the plugin itself as the "gateway" while we refer to the protocol handlers as "transports".
Copy the kraken.jar into the plugins directory of your Openfire installation. The plugin will then be automatically deployed. To upgrade to a new version, copy the new kraken.jar file over the existing file. Please be aware that an upgrade will cause all of the users on your server who are making use of the plugin to be disconnected from their external IM accounts. Your users should be reconnected after the plugin reloads.
By default, after the plugin has been deployed all of its features are disabled. This plugin is configured via the "Gateways" sidebar item located in the Openfire Admin Console. You can enable individual transports via the "Settings" sidebar item, and add new registrations/view existing registrations from the "Registrations" sidebar item.
Before going into specifics, there are some important things you need to know first. A user must be registered with a transport in order to make use of it. Registration is the process wherein a user tells a transport what username and password will be used with the external service. This process also places the transport JID in their roster to that the transport itself can "hear" them come online, and act appropriately (logging them in and such). In this case, we interact with the user's roster directly, so there is no need for a flood of subscription requests to the client itself. A side effect of this is that only users of the local Openfire server will be able to make use of any transport on the gateway. Roster items are created as non-persistent, which means that when the end user logs out or disconnects from the gateway, the associated transport roster items will no longer exist in their roster.
The web interface of the gateway plugin provides a mechanism for setting up registrations on a user's behalf, as well as editing and deleting them. It also provides tools for monitoring who is using the gateway, their status, etc. In a typical setup, a user will be allowed to register an account themselves. See the next section for details on this. You can also set who has access to the specific transports and even enforce manual registrations only. If a specific transport has any options, they will be made available from the web interface. You will see the full hostnames of the transports listed. You do not have to register these with your DNS service. They are referenced internally by Openfire and no external query is necessary.
If you have a firewall set up, you do not need to open any inbound ports. However, you will need to make sure the following outgoing connections will work based on the transport in question:
There is additional online documentation available at: Kraken's Online Readme
Typically, users will use Service Discovery (aka disco) to find out what services are available on a server, and then will be provided with a way to register with whatever transports are made available. Some clients do not have the functionality to interact with transports. In this case, a server admin will need to register the user on their behalf. (see above)
When registering with any Kraken transports, you will see the transport itself show up in your XMPP roster. This is normal and is how the transport knows when you are logged in or not, and detects status changes. Removal of the transport roster items will typically remove your registration with the transport as well.
Special note for Spark: As of this release, and an upcoming release of Spark, you will not have the transports in your roster when you register from Spark. This is an experimental feature for a smoother user experience. Note that if you register from Spark and then move to another client, you will not automatically log into any transports. If you plan to dance between clients and not use Spark exclusively, I would recommend you register from another client than Spark.
If the plugin behaviour is not as expected you can enable server debug logging. This will allow the plugin to start logging. Server debug logging should only be enabled temporarily, as it will generate a lot of additional logging that will both slow your server down and consume a lot of disk space.
Thanks to the Adium X folk for use of a couple of their service icons!