Saturday, 16 April 2011

SAP ABAP Webdynpro Interview Questions and Answers

1)   Types of ABAP UI Technologies
      Ans: Webdynpro for ABAP, BSP
2)   MVC Architecture Concepts and usage of the same in ABAP Webdynpro
      Ans: As per the MVC Architecture there is a clear separation between flow logic, view and the Business
              Logic. View holds all the UI elements that are visible in the UI, Controllers have the flow logic.
              Controllers are of different kind (Component Controller, View Conroller,Window Controller).
              Business logic is held in the Model which is in the form of Assistance class
              in webdynpro context.  
3)   Difference Between the View Container and the Transparent Container
      Ans: View Container holds the views, there can be multiple views assigned to the view container but only
      one view can be active(viewed) at a time. Transparent holds the webdynpro UI elements, A layout type
      can be associated  with it.
4)   What does a Model Class Consists of
      Ans: Model Class is the Assitance class in webdynpro. It contains the Business logic in the form of
      methods, Global data & Constants in the form of Class Attributes. The Model class can be accessed in
      webdynpro component using the attribute wd_assist->. Note: All the visibility properties of the
      Class are applicable when accessing the class using the object wd_assist.
5)   What is an Assistance Class and How is it Instantiated in Webdynpro
       Ans: Assistance Class is the model class which would act as the data provider  for the webdynpro
       component and it is instantiated by the webdynpro component during the run time and no explicat
       instantation is required.
6)   Design Patterns in Webdynpro(GAF,OIF,QAF Etc)
      Refer to the link:
      FPM Concepts in Webdynpro
7)   How do you debug an web based Application
      (Could be from ABAP Webdynpro, BSP or CRM Web UI)
       Ans: External break-points should be used to debug web UI's.
8)   How do you create a ALV Report/Editable ALV in Webdynpro
      Ans: ->Add the Standard ALV component to the web dynpro Component.
              ->Use Components tab: Ex: ALV_MATS  type SLV_WD_TABLE
              ->Create a context node with the table field information to be displayed
              ->Write the ALV Default Code for table display
              ->Set the read only attribute to false to switch to editable mode using
                 the method set_read_only of the interface 
                IF_SALV_WD_TABLE_SETTINGS implementing class 
9)   How do you Navigate between Views in Webdynpro
       Ans: Navigation between Views is through Plugs(Inbound and Outbound),
10) Usage of Plugs in Webdynpro
       Ans: Plugs are used to Navigate between the views. Parameters can be passed using the plugs similar to
       interface parameters of function module or a class method.
11) Usage of Webdynpro Component Controller
       Ans: Component controller is used to the store the Global attributes and Methods of the component.
       Attributes/methods declared in the component controller are visible through out the component and they
       are accessed using the attribute wd_comp_controller outside of component  controller(like
       views,windows etc) All the context nodes defined in the component controller are
       visible in all the views and windows of the component.
       Ex: if a variable called gv_count is defined in the component controller, it can be accessed in the view
       using the syntax wd_comp_controller->gv_count.
12) How do you access a Context Nodes and elements Programmatically
      Code required for accessing the Context Nodes can be written using the webdynpro code wizard.
      For Ex: if there exists a Node Node1 with cardinality 1:1 and has 3 Attributes to it Att1, Att2,Att3. The
      attributes can be accessed using the below code.

      data: lo_nd_node1 type ref to if_wd_context_node.
      data: lo_el_node1 type ref to if_wd_context_element.
      data: ls_node1 type wd_this->element_node1.

      lo_nd_node1 = wd_context->get_child_node
      ( name = wd_this->wdctx_node1 ).
      lo_el_node1 = lo_nd_node1->get_element( ).

**Read Node1
          static_attributes = ls_node1 ).

**Write to Node1
          static_attributes = ls_node1 ).

13) Message Areas in Webdynpro
      Message areas are created in views to display messages (Error,Success,Warning,Info).
      WD allows to have multiple Message errors in a view but throws an error when the view is displayed.
      Use the code wizard to get code for raising error messages. Few of the message classes and methods
      are: Interface: if_wd_message_manager.
      methods: report_t100_message.(used to report message from the  message class)
14) Concept of OTR(Online Text Repository) and its Usage
      OTR's are similar to text elements in ABAP. OTR's are created for
      UI texts and texts can be maintained in multiple language.
      OTR's can be created using the transaction: SOTR_EDIT
15) Concept of Interface Views
       If the views of a different components are need to be used in a webdynpro component mark the view as
       interface view and use it in another component. It's similar to using a include in a program.  A Interface
       view of the component can be used in any no of components. this concept supports the reusuability of
       the views.
16) Sequence of Webdynpro Events:
       Sequence: WDDOINIT of the component controller,
                       WDDOINIT of the Window Controller,
                       WDDOINIT of the View Controller,

      WDMODIFYVIEW(On Input/Display on any UI Element).
      WDBEFOREACTION(Method for validation of user input,
      Once the user action happens on the UI)
      WDAFTERACTION(Method for non-action specific operations
       before Navigation)
      WDDOEXIT( Exit from the View/Window/Component Controller)
      WDPOSTPROCESSING(used to perform exception handling for supply function methods)
17) Can a Component have Multiple Applications
       Yes, For a given webdynpro component any no of applications can be  created. Applications are similar
       to transactions in SAP.  You can associate different Interface views of the component to create different
       applications using the same component.
18) How do you launch a Webdynpro Application from a Transaction
      Refer to the previous blog Calling webdynpro application from a Transaction
19) How do you Navigate between two Webdynpro Components
      You can use Interface views to navigate between components or create a navigation class and
      do a explicit call.
20) Creating a tree in Webdynpro
      Tree UI element is used to create Tree  in Webdynpro. Tree can be defined as part of the table column.
21) Usage of Exit Plug in a Webdynpro Window
      Exit plugs are outbound plugs used to close the webdynpro application.  they can be called from the view
      which are embedded in the window  Note: Exit plugs won't work in portal environment.
      Exit plugs can also be used to pass the call to another URL. Here is the sample code snippet of the exit
      plug call:
      method onexit .

        data url type string.
        data close_window type wdy_boolean.
        url = 'url_name'.
        close_window = abap_false.
        wd_this->fire_to_exit_plg( url = url
                                                 close_window = close_window ).

22) why FQDN(Frequently Qualified Domain Name) is necessary for running Webdynpro Applications
      Refer to sap help:
21) Standard ALV Component required to create ALV Reports in Webydnpro
22) How do you build Select Options in Webdynpro
      Using the standard webdynpro component WDR_SELECT_OPTIONS
      You can refer to the example: WDR_TEST_SELECT_OPTIONS
23) How do you build F4 Search Help in Webdynpro
      A F4 help for an input field can be made available by attaching the search help
      to the table field. Usage of standard help component WDR_OVR.
      Creating a component for help and attaching it to the node element as Freely programmed value help
24) How are Plugs(Inbound/Outbound) bounded in the Window
      Plugs are created in the view and bounded in the window by using the drag drop option in the window
25) How do you Control the visibility of the Webdynpro UI elements Programmatically.
      Create a context element of type wdui_visibility and bind to the visibility property of the UI element.
26) What is the use of Interface views/nodes in Webdynpro.
       Interfaces nodes and views are created to use them in other webdynpro components.
27) How do you navigate between different Webdynpro applications
      Create a navigation class and trigger the target application to be called.
28) What are the webdynpro init  events and what is the sequence of trigger

       Sequence: WDDOINIT of the component controller,
                       WDDOINIT of the Window Controller,
                       WDDOINIT of the View Controller,

29) How are Error messages created and handled in webdynpro
      Create a message UI element in the view and trigger the message required(Error,warning,status) using the
      code generation wizard.
30) What is an OTR and mention its usage in Webdynpro
       Online Text Repository is the central storage for texts for webdynpro
       applications. An otr can be fetched in the program using the below mentioned code.
       data: lv_string type string.
        lv_string = cl_wd_utilities=>get_otr_text_by_alias(  alias =    
              'PACKAGE/OTR_NAME' ).

31) Can text elements be used in webdynpro, if yes how?
       Yes text elements can be used in webdynpro.
       Refer to the below code snippet.
        data: lv_string type string.
        lv_string = wd_assist->if_wd_component_assistance~get_text(  '025' ).     
32) What is the use of Road Map UI element
       Roadmap UI element is used to display step-by-step workflows. It can used to clearly define a process.
33) What are exit plugs?How are they created?
      Exit plugs are used to exit from the webdynpro page or an webdynpro window.
      Exit plugs are created in the window.
34) Is it possible to hide F4 function for an Input element programmatically?
      Yes it is possible to hide F4 function attached to an input field.Use the interface
      if_wd_context_node_info and the method set_attribute_value_help
35) How do Webydnpro Upload and download functions work, Explain.
      Fileupload UI element is used upload files from desktop the application.
      There is also restriction on the max data volumes that can be uploaded.
      Filedownload UI element is used to download files to the client.
36) Explain the concept of Road Map UI element in Webdynpro.
      Refer to the link: Road map UI element webdynpro for abap
37) How to create popups in webdynpro.
      Create a view and embed the view in the window and call the window to trigger the popup.
38) Explain the concept of OVS and its usage
      WDR_OVS is the standard webdynpro component to generate F4 helps
      for the input field. OVS refers to Object value selector.
39) Using Radio Buttons/Checkboxes/Dropdown lists in webdynpro
      Radio buttons/Checkboxes are used for objective selection similar to what is available in SAP GUI. An
      event is associated with each UI element for onclick action.
40) FPM Concept and its usage in webdynpro.->>>>Refer to the link

41) what is internationalization in webdynpro abap application?
      Internalization refers to creation of texts used in webdynpro application in a specific language and
      providing option to translate to multiple languages if necessary. This is achieved by using OTR's or text
      elements for static texts and performing translation when required.
42) What is Cardinality of a context node in webdynpro
       Cardinality refers to no of elements a node can accomodate during run time. When a node is created the
       cardinality is assigned to it. Cardinality is of the following kinds:
       0:1 -->At run time, no element or maximum one element can be instantiated
       0:n -->At run time, no element or maximum of n elements can be instantiated
       1:n -->At run time, minimum one element or maximum of n elements can be instantiated
       1:1 -->At run time, only one element should always be instantiated
       if you try violating the cardinality there would be a short dump saying Number of elements of the
       collection of node node_name violates the cardinality
 43) what is Personalization in abap webdynpro application
        Personalization refers to changing the properities of UI elements at runtime. Personalization settings are
        user specific. Configuration controller is used for personalization function.
        ex: Changing the order of columns in a table display.
 44) what are the controller types in webdynpro ABAP
        -Component Controller->Component Controller is global part of the component and each component
          has only one component controller. Global Attributes and  methods required by the component can be
          defined here.
        -Custom Controllers->Custom controllers are defined during design time and  these are optional. The
          visibility Custom controllers is in the entire component and has the life time equal to life time of the
          component. Custom controllers are used if a set of views have to be grouped to perform
          a special function or hold a set of data.
         -View Controller->Flow logic of the views are in view controller and a view can  have only one view
           controller. The visibility of View controller is specific to view only.
         -Configuration Controller->Configuration controller is used achieve personalization function.
         -Window Controller->A window controller exists for each window and can also have methods
           to write coding logic. Every window will have the default method and it is used to  receive
           parameters. The windows controllers are visible in entire component and also in the custom         
45)what are Layout types in Webdynpro and its usage
         ->Flow Layout  : Used for sequential display of WD UI elements.
         ->Row Layout  : here each ui element is displayed on its own column and the width differs from row to
             row.Rowheaddata is used to insert a break.
         ->Grid Layout  : Ui elements are arranged based the no of columns. line breaks  are inserted based on
             the size.
         ->Matrix Layout: Matrix layout arranges ui elements in columns. Matrixheaddata is used to insert a line
            Usage of the appropriate layout to build a webdynpro application is determined during the UI
 46)what is supply function method in SAP
         ->Supply function method is used to populate the context node or to default values to the context
             node elements. supply function method is called before the node is accessed for first read.
         ->Using supply function method is optional
47)what is singleton property of context node
         ->Singleton property is one of the attributes of the context node if this is set there can be only one
             instance of the respective context node at runtime.
48)How to default a value to the context attribute
     In the context attribute there is a property to set the default value. Use the same, However the
     default value can be overwritten using the set_attribute method of the interface if_wd_context_element.
49)Is it possible to pass parameters to webdynpro URL?
     yes you can pass parameters to webdynpro URL and it is passed as below.
     for ex: your url is
     Here the parameter values are passed for sap-system-login-basic_auth,sap-client and sap-language.
    ***********************More to Come********************


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  17. nice post thanks for sharing valuable information from Swathi