Webdynpro ABAP Introduction Overview for Beginners

SAP Web dynpro, ABAP Webdynpro is the SAP standard UI(User Interface) technology. ABAP Web dynpro used for developing web based business applications without knowing HTML(Hyper Text Markup Language) or Javascript. 

SAP Webdynpro is developed using ABAP and also Java, here in this post we are going to know about detail over view on SAP Webdynpro ABAP introduction and webdynpro tutorial. Click on read more to view this article.

SAP Webdynpro ABAP Introduction Tutorial

SAP Webdynpro ABAP, Webdynpro is the SAP standard UI(User Interface) technology used for developing web based business applications without knowing HTML(Hyper Text Markup Language) or Javascript. SAP Webdynpro is developed using ABAP and also Java here in this post we are going to know about detail over view on SAP Webdynpro ABAP.

What is Web Dynpro:

--> Webdynpro is the SAP standard UI technology used for developing web business applications without knowing HTML or Javascript

--> Strict separation between the layout and business data

--> Reuse and better maintainability through reusability

--> Automatic input checks

--> Automatic data transport using data binding

--> WYSIWYG view editor

Contents of Webdynpro:

Concept of View

Components of View Layout

Properties Tab

Context Tab

Methods Tab

Attributes Tab

Concept of Component Controller

Application

Displaying Messages

Supply Function

Cardinality Property

Singleton

Lead Selection

Hook Methods

Types of Controllers

Hook Methods Chart

View and it's Concept :

We can add different UI elements that can be nested on in the other one to create the screen.

Each view has a view controller that is automatically created for this view and each view has several tabs (Properties, Layout, Outbound Plug, Inbound Plug, Attributes, Context, Actions and Methods).

Components of View Layout:

1) UI Element Library

2) View Designer

3) Context Menu

4) UI elements properties and

5) UI element Hierarchy

1) Properties Tab:

Here we can set the lifetime of the view

1) Framework controlled – Controller by Framework

2) When Visible – Lifetime limited to its visibility. 

2) Context Tab:

The data are stored in the context and the UI elements are only objects the user interacts with.

3) Methods Tab in webdynpro:

Event Handler Methods

Hook Methods and (wddoinit, wddoexit etc)

User-defined instance methods

4) Attributes Tab in web dynpro:

i) wd_context:

It is a reference to the controller context. IF_WD_CONTEXT_NODE interface provides several methods that enable us to obtain read and write access to a context node.

ii) wd_this:

This is a self reference to local controller interface. We can use it to call user defined methods.

iii) wd_comp_controller:

It is a reference variable of IG_COMPONENT CONTROLLER type that we can use to access all the publically accessible methods of the component global generated interface of the corresponding component controller.

Concept of Component Controller in webdynpro

Data required across different views can be stored in this context

Application:

For the execution of the Web Dynpro Component.

Displaying Messages:

On the properties tab of an application we can specify how the messages are handled.

1) Show Message component on demand

2) Always display message component

Supply Function:

Each node may have a supply function defined for it and automatically called by the Web Dynpro Framework.

The scope of using a supply function is to populate a context node. In certain cases , we can use the Hook Method wddoinit instead of a supply function.

Cardinality Property:

It tells us how many elements a context node may have at runtime.

1 to 1 – Exactly one context element is instantiated

0 to 1 – Maximum one context element is instantiated

0 to n – Zero or more context element is instantiated

1 to n – One or more context element is instantiated 

Singleton:

Unlike the Cardinality of a node which describes the number of possible elements within the node the ‘Singleton’ property determines whether or not these elements are set for all the parent node (Non-Singleton) or for exactly one element of the parent node (Singleton).

Lead Selection:

At runtime, every child set as a singleton contains elements for exactly one element of the parent node. For this purpose, one element from the set of possible elements of the parent node must be highlighted.

This is achieved by initializing lead selection. For each newly created context node, lead selection is initialized automatically.

Hook Methods:

These methods cannot be deleted and represent the interface between the Framework and our application. The Hook Methods are called in a specific sequence according to a Phase Model.

Types of Controllers:

1) Component Controller

2) View Controller

3) Window Controller

4) Custom Controller

Hook Methods Chart:

1)wddoinit():

Ø This method can be considered the controller constructor. It is automatically called when the controller is initialized for the first time.

2) wddoexit():

Ø This method can be considered as the controller destructor. It is automatically called when exiting the controller, and can be used for executing closing statements.

3) wddomodifyview():

Ø This method is mostly used in the dynamic programming, it is a method used for modifying the view before rendering.(Dynamically modifying the view)

4)wddobeforeaction():

Ø We can use this method to perform our own validation before an action is triggered.Check_mandatory_attr_on_view)

5) wddocontextmenu():

Ø It is used to provide the hierarchical context menus in Web Dynpro views.

Ø We can create a context menu at design time, by using the CONTEXT_MENUS root, or dynamically, by coding the wddooncontext menu method.

6) wddoafteraction():

Ø This method is called for all visible views at the time an action is executed.

Ø Here functions can be placed that are carried out equally for all associated event handlers.

Ø This avoids any unnecessary multiple programming in the event handlers.

7) wddoonopen() & wddoonclose()

There are two methods are only processed when a window is opened or closed as a dialog box.

Since the opening of dialog box does not involve any navigation, no inbound plug is called and therefore no event handler method is processed.

The wddoonopen method can therrefore be used to implement initializations.

8) wddodobeforenavigation():

It can be used to perform an additional validation of those controller contexts that are required in the application but have not been validated in the request/response cycle yet.

This is important for more complex Web Dynpro applications in particular. This method is used for the component assigned to the phase model instance and all embedded components.

9) wddopostprocessing():

This method is called in the process step before rendering. Therrefore it allows you to add application specific clean-up processes.

10) Wddoapplicationstatechange():

This method replaces the ‘WDDOEXIT’ method in the phase model.

Web Dynpro ABAP Interview Questions

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