Context, nodes and attributes of a Web Dynpro ABAP Component

what is a context ?, what is a node ? in web dynpro for ABAP

+ -

Context

  • Every Web Dynpro ABAP application need to store some data at run time, context acts as a data container of a Web Dynpro application
  • Context is a temporary place where we declare data deceleration's in the form of nodes and attributes.
  • Each context has a hierarchical structure. It contains a root node CONTEXT and the different context elements are arranged below it. You can create new context nodes and individual context attributes below each context node.
  • Context contains nodes and attributes

Web Dynpro ABAP Context

Attribute

It is used to store a single value, these are similar to fields in table or structure.

Ex: MATNR, MTART, VBELN

Node

Node is a collection of attributes, it is similar to structure or internal table.

Properties of node

Cardinality

It specifies how many records that can be stored in a node, four options are available under cardinality.

Minimum Maximum Description
0 1 Node can store only one record i:e same as work area.
Node can only be filled through back end logic only ( can not be used for user input ).
1 1 Node can store only one record I:e same as work area
Node can be used for user input .
0 n
Node can store maximum 'n' number of records.
Node can only be filled through back end logic only ( can not be used for user input )
1 n
Node can store 'N' number of records I:e same as internal table
Node can be used for user input .

If maximum value = 1, it can store 1 record.
If maximum value = n, it can store 'N' records.

If minimum value = 0, data is selected from back end (using select, itab etc).
If minimum value = 1, data can be selected from front end (user input).

Understanding for Basic Users

For basic understanding, here I am comparing web dynpro with ABAP.

In ABAP we declare internal table like below.

DATA : IT_MARA TYPE TABLE OF MARA.

In web dynpro we create a node for mara with cardinality 0-n or 1-n, both can store 'n' number of records(Internal table can store n records).In future lesson we will learn when to take 0-n and 1-n cardinality for creating a node.

In ABAP we declare work area like below.

DATA : wa_MARA TYPE MARA.

In web dynpro we create a node for 'MARA' with cardinality 0-1 or 1-1, both can store one record only(work area can store only one record).In future lessons we will learn when to take 0-1 and 1-1 cardinality .

Learner Questions


No Questions by learners, be first one to ask ..!!

    Please Sign in to ask a question

    Was this lesson helpful to you? Yes No 89 People out of 91 think this lesson helpful


    Lesson Navigation

    ←Previous Chapter
    Next Chapter →