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SAP AG 2005, Title of Presentation / Speaker Name / #

The structure of the context

Context mapping

Internal mapping

Contents:

The Context At Design Time


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After completing this topic, you will be able to:

Understand the structure of the context

Use the context editor

Use internal context mapping

The Context At Design Time: Topic Objectives


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The Context - The Heart of a Controller

Controller

Implementation

StandardHook

Methods

Instance

Methods

Context

Root Node

RequiredControllers

ControllerInterface

Other WDControllers

CustomController

BusinessLogic

(Models)

Created by explicit declaration or coding Created by the Web Dynpro Framework (WDF)

ComponentUsage

Other WDComponents


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Changing the Context

1) Open a controller (view orcustom) using the Changeoption in the context menu

2) Choose the Contexttab.

3) Display the Propertybyselecting the CONTEXTnode


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Context Structure Design Time (1)

Context Root Node

Node

Attribute

Context menu on the Context Root Node

Context Node:

Are arranged hierarchically and are permitted to have children

Children of a node may be entities known as other nodes or attributes

Metadata description declared manually or derived from a Dictionary Structure

Context Attribute:

Stores runtime data or references to runtime data

Based on DDIC Types


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Node Metadata (c=cardinality, s=singleton)

IF_WD_CONTEXT_NODE_INFO (interface)

Attribute Metadata (data type)WDR_CONTEXT_ATTRIBUTE_INFO (structure)

Context Structure Design Time (2)

All context nodes are collections.

A node collection is composed of

elements, where an element is anaggregation of the nodes immediate

children (attributes and/or other nodes).

The cardinalityproperty controls thenumber of elements a node collection

may hold at runtime.Design time

A node collection

Context Root (c=1..1, s=true)

FLIGHTS (c=0..n, s=true)

PRICE

Context Metadata

CARRID

CONNID

FLDATE

Context Metadata

BOOKINGS (c=0..n, s=false)

BOOKID

CUSTOMID

CLASS

PASSNAME


7/16 SAP AG 2005, Title of Presentation / Speaker Name / #

Context Structure Runtime (1)

All independent nodes are forced to be singletons. This is

because the context root node has one and only one element.

c=1..1, s=true

Independent Node

1Default

Element

c=0..1, s=true

Independent Node

1

Context Root Node

c=1..1, s=true

1Default

Element

= Element created by an application at runtime

= Element created by the WDF at context initialisation time

Node collection is initially empty.

Can contain a maximum of one element.

Node collection contains a default element.

Can contain a maximum of one element.




Context Root Node

c=1..1, s=true

1Default

Element

= Element created by an application at runtime

= Element created by the WDF at context initialisation time

Node collection is initially empty.

Can contain as many elements as required.

Node collection contains a default element.

Can contain as many elements as required.

= Element at the lead selection

c=0..n, s=true

Independent Node

..n2

1

c=1..n, s=true

..n2

Independent Node

1DefaultElement

All independent nodes are forced to be singletons. This is

because the context root node has one and only one element.




Design Time

Context Root

0Default

Element

The runtime structure of the

context if node BOOKINGS is a

non-singleton.



PRICE

Context Metadata

CARRID

CONNID

FLDATE

Context Metadata

BOOKINGS (c=0..n, s=false)

BOOKID

CUSTOMID

CLASS

PASSNAME

..nCARRID

CONNID2CARRID

CONNID1CARRID

CONNID

FLDATE

FLIGHTS

BOOKINGS

..nBOOKID

CUSTOMID2BOOKID

CUSTOMID1BOOKIDCUSTOMID

BOOKINGS

..nBOOKID

CUSTOMID2BOOKID

CUSTOMID1BOOKID

CUSTOMID

BOOKINGS

..nBOOKID

CUSTOMID2BOOKID

CUSTOMID1BOOKID

CUSTOMID

Runtime





PRICE

Context Metadata

CARRID

CONNID

FLDATE

Context Metadata

BOOKINGS (c=0..n, s=true)

BOOKID

CUSTOMID

CLASS

PASSNAME


Design Time

Context Root

0Default

Element

The runtime structure of thecontext if node BOOKINGS is a

singleton.

BOOKINGS

..nBOOKID

CUSTOMID2BOOKID

CUSTOMID1BOOKID

CUSTOMID

Runtime

..nCARRID

CONNID2CARRID

CONNID1CARRID

CONNID

FLDATE

FLIGHTS



Context Structure Why Singleton nodes?

Context Root

0Default

Element

Q: Why do singleton nodes exist?

A: Efficiency!

This design of context structure both copies

the way users handle business data, andcauses the Web Dynpro application to

consume significantly less memory.

BOOKINGS

..nBOOKID

CUSTOMID2BOOKID

CUSTOMID1BOOKID

CUSTOMID

..nCARRID

CONNID2CARRID

CONNID1CARRID

CONNID

FLDATE

FLIGHTS



Supply Function

Context node can be assigned a supply

function

This supply function is called by the runtime

when the data of the context node is required

Especially useful in combination with singleton

nodes

Context Root

BOOKINGS

..nBOOKID

CUSTOMID2BOOKID

CUSTOMID1BOOKI

DCUSTOMID

..nCARRID

CONNID2CARRID

CONNID 1CARRID

CONNID

FLDATE

FLIGHTS

Supply function

BOOKINGS_READ



Context Mapping

Context mapping is the primary mechanism for

sharing data between different controllers.

Advantages:

Data is automatically available to all

controllers using the mapping relationship

Only one copy of the data is ever maintained

Data can be mapped selectively, thus reducing

the amount of data in a controllers context to

the minimal set required to fulfil a task



Context Mapping

Drag and drop structure

or create a node anddefine the mapping

After the mapping themapped structure appears

in the target context

In the property of the node the mapping path is visible



W e b D y n p r o C o m p o n e n t

Context Mapping: Internal Mapping

View Controller Component Controller

Mapping Relationship

Context Root

FLIGHTS

Mapped node collection Node collection of mapping origin

Controller

Usage

Declaration

Context Root

BOOKINGS

BOOKID

CUSTID

CLASS

PASSN

PRICE

CARRID

CONNID

FLDATE

BOOKINGS

BOOKID

CUSTID

CLASS

PASSN

PRICE

CARRID

CONNID

FLDATE

FLIGHTS


16/16 SAP AG 2005 Title of Presentation / Speaker Name / #

You should now be able to understand:

The Structure of the Context

Internal Context Mapping

The Context At Design Time: Unit Summary

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