Events

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Events
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Events

• Events are used to allow a controller to inform
  another controller (whether its in the same
  component or another component) that something
  has occurred
• Events are particularly important in situations
  in which communication must take place against
  the direction of a usage relationship

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Events
Parent component uses the component interface
controller of thechild component giving the
ability toexecute methods in the
componentinterface controller.
Parent Component
ComponentController
Usage
ComponentInterface Controller
Child Component
However, if the child component cannotexecute
code in the parent componentso if it needs to
communicate with theparent component it must
raise an eventin its component interface
controllerto which the component controller of
theparent component subscribes. This causesa
an event handler method in the parentcomponent
controller to execute.
ComponentController
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Events

• Events can be defined for all controllers except
  view controllers and interface view controllers
• Events cannot be defined in view controllers
  because they have no public interface to make the
  events available
• Controllers can subscribe to the events defined
  in other controllers if a usage relationship is
  established
• When the event is fired, an event handler method
  executes in the subscribing controller

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Firing an Event

• Event is defined in controller A
• Method is created in controller A which fires the
  event by executing the code wdThis.wdFireltevent
  namegt()
• Method can be executed by an action or by some
  other code
• Controller that subscribes to the event executes
  and event handler when the event is fired
• Parameters can be passed

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Event Handler
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Event firing
public void fireEvent( java.lang.String text )
//_at__at_begin fireEvent()
wdThis.wdFireEventAnEvent(text) //_at__at_end
public void reactToComponentEvent(com.sap.tc.webd
ynpro.progmodel.api.IWDCustomEvent wdEvent,
java.lang.String text ) //_at__at_begin
reactToComponentEvent(ServerEvent) //Whatever
code is required to handle event //_at__at_end
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Action Events
public void onActionGo( com.sap.tc.webdynpro.progm
odel.api.IWDCustomEvent wdEvent )
//_at__at_begin onActionGo(ServerEvent)
wdThis.wdFirePlugToResultView() //_at__at_end
public void onPlugfromStartView( com.sap.tc.webdy
npro.progmodel.api.IWDCustomEvent wdEvent )
//_at__at_begin onPlugfromStartView(ServerEvent) Stri
ng headerText "Congratulations " headerText
wdContext.currentContextElement().getHeaderText
() headerText "!" wdContext.currentContextE
lement().setHeaderText(headerText) //_at__at_end