Shoal's client API is provided in this package. The entry point for
clients using GMS is the GMSFactory class. This class
provides the APIs for getting a GroupManagementService
instance for a given member name, group name, member type and
configuration. The GroupManagementService
instance provides methods for registering interest in specific group
events.
To process group events on the client side, Shoal makes it easy for
clients by providing a single interface that needs to be implemented,
namely, the CallBack interface. This interface provides a
method processNotification() that accepts a Signal
object. Signals are of various types - each type corresponding to a
specific group event. Clients register interest in these events by
using addActionFactory() methods provided in
GroupManagementService. The clients pass in an instance
of a specific ActionFactory type to the method.
The ActionFactory is a client side artifact with its
sub-types corresponding to a specific group event. One can think of the
ActionFactory-Action-Signal triplet
as a set of one-to-one correspondence objects for a specific type of group event.
Clients can choose to implement a specific ActionFactory and
Action type or use the reference implementations provided in the
com.sun.enterprise.ee.cms.impl.client package.
For instance, clients simply implement the CallBack interface and register
for group events using the default implementation of the, say,
FailureNotificationActionFactory to receive notifications for
failure events in the group.