05 ABAP Objects - Events Handling

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© IBM Corporation 2013


Defining and Registering Events in Object Oriented ABAP




© IBM Corporation 2013Developing User Interfaces with Web Dynpro for ABAP | Jan-2011 2

Agenda

Define and trigger events

Register and handle events





Unit Objectives

Define and trigger events

Handle events

Register and deregister events

Receive a reference from the sender

Explain the conceptual differences between methods and events





Overview





Characteristics and Uses

Looser linkage than for a method call

Different communication model

Trigger does not know the user

Important for GUI implementation

Conformity to other object models COM

ActiveX Controls

OpenDoc





Triggering and Handling Events: Overview

Triggering events Class defines event (EVENTS, CLASS-EVENTS)

Object or class triggers event (RAISE EVENT)

Handling events Event handler class defines and implements event handler method

([CLASS-]METHODS... FOR EVENT ... OF ...)

Event handler object” or handler class registers itself to specific object/class events at runtime (SET HANDLER)





Defining and Triggering Events: Syntax





Handling and Registering Events





Handling Events: Syntax





Registering for an Event: Syntax





Deregistration and the Implicit Reference SENDER





Registration/Deregistration: Handler Table





Defining View Layout

Event handling is sequential.

Sequence in which event handler methods are called is not defined.

As far as the Garbage Collector is concerned, registration has the same effect as a reference to the object registered.

Registered objects are never deleted.

Immediate effects of SET HANDLER on event handler

methods:

Newly registered event handlers are also executed.

Deregistered handlers may already have been executed.





Events and Visibility

The visibility of an event establishes authorization for event handling.

The visibility in an event handler method establishes authorization for SET-HANDLER statements.

An event handler method must have either the same or more restricted visibility than the event it refers to :





Events: Unit summary

You are now able to: Define and trigger events

Handle events

Register and deregister events

Explain the conceptual differences between

methods and events





Hands-on Exercise 8

Objectives: Define and trigger events

Handle events

Register for events





Thank You

Questions?

Documents

05 ABAP Objects - Events Handling