Jolt 1.2 Developer's Guide

JavaBeans Events and NonStop
TM
TUXEDO Events
JavaBeans communicate via events. An event in a NonStop
TM
TUXEDO system is different from an event in a
JavaBeans environment. In a NonStop
TM
TUXEDO application, an event is raised from one part of an application to
another part of the same application. JoltBeans events are communicated between beans.
Using NonStop
TM
TUXEDO Event Subscription and Notification With JoltBeans
NonStop
TM
TUXEDO supports brokered and unsolicited event notification. Jolt provides a mechanism for Jolt clients to
receive NonStop
TM
TUXEDO events. JoltBeans also include this capability.
Note
NonStop
TM
TUXEDO event subscription and notification are different from JavaBeans
events.
The following example shows how the NonStop
TM
TUXEDO asynchronous notification mechanism is used in
JoltBeans applications.
Use the setEventName() and setFilter() methods of the JoltUserEventBean to specify the NonStop
TM
TUXEDO
event to which you want to subscribe.
1.
The component that is to receive the event notifications registers itself as a JoltOutputListener to the
JoltSessionBean.
2.
subscribe() is called on JoltUserEventBean.3.
When the actual NonStop
TM
TUXEDO event notification arrives, JoltSessionBean sends a JoltOutputEvent to its
listeners by calling serviceReturned() on them. The JoltOutputEvent object contains the data of the NonStop
TM
TUXEDO event.
4.
When the client is not interested any more in the event, it calls unsubscribe() on the JoltUserEventBean.
Note
If the client is to subscribe only to unsolicited events, use setEventName ("\\.UNSOLMSG")
that can be set using the property sheet. EventName and Filter are properties of the
JoltUserEventBean.)
How JoltBeans Use JavaBeans Events
A Jolt client applet or application that has been built using JoltBeans typically consists of Jolt-aware GUI Beans, such as
JoltTextField or JoltList, and JoltBeans, such as JoltServiceBean and JoltSessionBean. The main mode of
communication between Beans is by JavaBeans events.
Jolt-aware beans are sources of JoltInputEvents or listeners of JoltOutputEvents or both. JoltServiceBeans are sources of
JoltOutputEvents and listeners of JoltInputEvents.
The Jolt-aware GUI Beans expose properties and methods so you can link the beans directly to the parameters of a
NonStop
TM
TUXEDO service (represented by a JoltServiceBean). Jolt-aware beans notify theJoltServiceBean via a
JoltInputEvent when their content changes. The JoltServiceBean sends a JoltOutputEvent to all registered Jolt-aware
beans when the reply data is available after the service call. The Jolt-aware GUI Beans contain logic that updates their
contents with the corresponding output parameter of the service.
Figure 1-1 shows a graphical representation of the possible relationships among the JoltBeans.
Figure 7-1. Possible Interrelationships Among the JoltBeans