14 - wd_dataflow context mapping and model binding

8/6/2019 14 - WD_dataflow Context Mapping and Model Binding

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Matthias Weidlich

Web Dynpro:Context Mapping & Model Binding

Seminar System Modeling

08.06.05


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HPI, Seminar System Modeling - SS2005 / 2

Agenda

Context Concept

usage of contexts

general structure

context properties

supply functions and context programming

Data Flows in a Web Dynpro Application

overview

data binding

context mapping

model binding

model import

connection to model at runtime

In a Nutshell

References


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Context Concept: Usage of Contexts

contexts are the main concept for storingand passing data in Web Dynpro

each controller has its own context

all data used in controllers or views is

stored in the context of the correspondingcontroller

a context represents a hierarchical datamodel

a context describes entities and their

relations, so it can be compared to an ERModel


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Context Concept: General Structure

a context is always

structured as a tree,

consisting of nodes

and attributes

each context has a root node, underneaththe data fields are stored

nodes represent data structures, attributes

represent data elements

Context Element

Subnode

name cardinality selection singleton

Root Node cardinality = 1..1

Value Node

leadSelection

Model Node modelClass

Context

Node Attribute name readOnly

Value Attribute calculated type

Model Attribute

consists

of

"consists

of


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Context Concept: Cardinality

Boat

Controller

b3

Red

b2

Green

Sailor

s1 05.05. 07.05.

s5 12.06. 13.06.

Sailor

redb3

greenb2boat_colorboat_ID

Johns5

Jims1sailor_namesailor_ID

13.06.12.06.s5b207.05.05.05.s1b2

rented tillrented fromsailor_IDboat_ID

Lending

rented from

rented till

Boat

boat_ID

color

Sailor sailor_ID

name


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Context Concept: Cardinality (2)

node elements represent either

an individual instance

of an object type

or a list of instances

this property of a nodeis called cardinality

cardinality is specified

via min appearance ..max appearance:

(0)1..1: the node

contains only one

element instance which

has (not) to be instantiated0(1)..n: the node can contain multiple element instances (at least one)

leadSelection marks one element in an element list

Element in

Design Time

1:1 Node cardinality = 1..1

0:1 Node cardinality = 0..1

1:n Node

cardinality = 1..n

0:n Node cardinality = 0..n

Element in

Runtime

Node

Element0..1

List ofNode

Elements

1..n

0..n

consists

of

can be

mapped to


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Context Concept: Type and Calculated

type declares the data type of the attribute (type can be Java NativeType, but should be a Java Dictionary Type)

calculated = true means the attribute is not stored as a memory object,but will be automatically calculated by the Web Dynpro Runtime on

demandon demand: the attribute is accessed by a layout controller or somecontroller coding

body of setter- and getter- method is generated automatically, thedeveloper has to code the calculation part

code example for calculated property:

java.lang.String getUserFullName (

IPrivateFormView.IUserDataElement element) {

//@@beginreturn element.getFirstname() + + element.getLastname();

//@@end

}


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Context Concept: Singleton

singleton = true means that the elements of the relevant node areinstantiated for only one element of the parent node (leadSelection)

Boat

Controller

b3

Red

b2

Green

Sailor

s1 05.05. 07.05.

s5 12.06. 13.06.

Sailor

State5


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Supply Functions:

special type of controller methods for creating context attributes in

value nodes

method body with user coding area is automatically created

often used in connection with singleton nodes

context programming:

generic APIs

needed for the dynamic creation of new context elements at runtime

use global interfaces, e.g. IWDContext, IWDNode, IWDNodelement

typed APIs

typed APIs are automatically created for statically defined contextelements

method signatures contain the corresponding object typesuse interfaces that are derived from the global interfaces, e.g.IContextNode, INode

Context Concept: Supply Functions & Context Progr.


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Data Flows in a Web Dynpro Application

data binding:link betweenview layout andview controllercontext

context mapping:link between twoglobal controllercontexts orbetween globalcontroller

context and view

controllercontext

model binding:link betweenglobal controller

context and WebDynpro Model

Web Dynpro Application

View

Controller

Model

Custom

Controller

Model

Agent

Web Dynpro Runtime

Custom Controller

Context

View Controller

Context

View Layout

to backend system

to

presentation

server


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Data Flows: Data Binding

data binding:link betweenview layout andview controllercontext

1:context elementthat has notbeen bound

2:UI element that

has not beenbound

3, 4, 5:UI element /context element

that has beenbound


View

Controller

Model

Custom

Controller

Model

Agent

Web Dynpro Runtime

Custom Controller

Context

View Controller

Context

View Layout

to backend system

to

presentation

server

2 3 4 5

1


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Data Flows: Data Binding (2)

properties of the user interface elements can bebound to attributes respectively nodes of a view context

context attributes have to be Java Dictionary Types, as Java Native Typescannot be bound

any user changes to the UI element properties in the view are immediatelyvisible in the context

as the same data storage is assigned, no data transport is necessary

if the UI element property

is a field of values (e.g. a table), the bound node has to be a multiplenode (cardinality = 0/1 . . n)

is a single value bound to an attribute of a multiple node,leadSelection marks the value to show

UI ElementUI Element

Property

Context Attribute

Value Attribute

Node Attribute

is bound toconsists of


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Data Flows: Context Mapping

context mapping:link between twoglobal controllercontexts orbetween globalcontroller

context and viewcontrollercontext

1, 2:

context elementthat has not beenmapped

3, 4, 5, 6:context element

that has beenmapped


View

Controller

Model

Custom

Controller

Model

Agent

Web Dynpro Runtime

Custom Controller

Context

View Controller

Context

View Layout

to backend system

to

presentation

server

2 3 4

1

5 6


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Data Flows: Context Mapping (2)

locally defined attributes areonly visible for thecorresponding controller

mapped attributes are visible atboth ends of the mapping

again: the same data storage isassigned, no data transport is

necessary

constraint:

attribute 1 can only be mappedon attribute 2, if one of the

parent nodes of attribute 1 ismapped on one of the parentnodes of attribute 2

Nodeconsists

of

Value Node

Model Node

is mapped to

AttributeValue Attribute

Model Attribute

is mapped to

is mapped to

is mapped to

consists

of


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Data Flows: Model Binding

model binding:link betweenglobal controllercontext and WebDynpro Model

1:model elementthat has not beenbound

2:context element

that has not beenbound

3, 4, 5:context element /model element

that has beenbound


View

Controller

Model

Custom

Controller

Model

Agent

Web Dynpro Runtime

Custom Controller

Context

View Controller

Context

View Layout

to backend system

to

presentation

server

2 3

4

1

5


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Data Flows: Model Binding (2)

Web Dynpro model:

data structure that represents the

data and functionality

of the backend

all model classes have to implement the

Common Model Interface (CMI)

CMI affects data management and eventhandling

access to CMI classes:

with generic methods

with typed getter- and setter methods

Model Element

Model Class name

Non Executable

Model Class

Executable

Model Class

Model

belongs

to

Model Property name type

consists

of


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Data Flows: Model Binding (3)

constraint:a context model attribute can only be mapped on a model attribute, if oneof the parent nodes of the context model attribute is mapped on one of theparent classes of the model attribute

Model ElementContext Element

Model Class

Model AttributeContext

Model Attribute

Context

Model Node

is bound to

Model

consists of


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Data Flows: Model Import

supported model types:

UML Web Dynpro Model in the XMI format

webservice description as WSDL

Java Bean model

Remote Function Call (RFC) model

import wizard generates the classes out of the model

Import

Wizard

Model

Agent

R

Model Data

to WebDynpro

Runtime

Models

Webservice Model

(WSDL)

UML Web Dynpro

Model (XMI)Java Bean Model

RFC Model


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Data Flows: Connection to Model (J2EE based)

J2EE based Web Dynpro Runtime communication:

to webservice via SOAP

to J2EE backend server via Remote Method Invocation (RMI)

to ABAP backend server by using the SAP Java Connector (SAP JCo)

SAP JCo is a middleware component that supports ABAP calls JAVAand JAVA calls ABAP

Model

AgentWebservice Provider

J2EE Backend Server

ABAP Backend Server

R

(RMI)

R

(SOAP)

R

(SAP JavaConnector)

J2EE Web

Dynpro

Runtime

R

Backend

Data

Backend

Data

Backend

Data

Model Data


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Data Flows: Connection to Model (ABAP based)

ABAP based Web Dynpro Runtime communication:

again: to webservice via SOAP

to ABAP backend server directly by calling RFCs and BAPIs

access to SAP Business Objects is gained by standardized methods:

Business Application Programming Interfaces (BAPIs)Remote Function Calls (RFCs) are a SAP standard for communicationbetween applications on SAP systems as well as non-SAP systems

Model

Agent

Webservice Provider

ABAP Backend Server

R

(SOAP)

R

(RFC, BAPI)

ABAP Web

Dynpro

Runtime

R

Backend

Data

Backend

Data

Model Data


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In a Nutshell

contexts are the main concept for data management in WebDynpro

a context is a data model

data flows in Web Dynpro:

data binding links properties of user interface elements andcontext attributes

context mapping links context elements

model binding links context elements and elements of themodel


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References

Web Dynpro Overview, McNulty, SAP AG, 2003Creating your first Web Dynpro Application, SAP Online Help, SAP AG 2004

Creating an Email client using Web Dynpro, SAP Online Help, SAP AG 2004

Java-Programmierung mit dem SAP Web Application Server, Kessler, Tillert,

Dobrikov, Galileo Press, Bonn 2005Introduction to Web Dynpro, SAP Developer Network, www.sdn.sap.com

Web Dynpro Architecture, SAP Library, www.help.sap.com

Business Application Programming Interfaces, tse - technologieberatung undsystementwicklung, Hamburg 2005, http://www.tse-

hamburg.de/Papers/SAP/sapBAPI.htmlSAP BAPI und SAP JCo, Horn, 2005, http://www.torsten-horn.de/techdocs/sap-bapi.htm

Application Server, Web Application Server, Web Services, SOAP, Java,

Horn, 2005, http://www.torsten-horn.de/techdocs/applicationserver.htm

Wiederverwendbare Software (Web Dynpro), Tillert, 2004, www.sap.infoThe new face of SAP - Web Dynpro, Winkler, 2004, http://www.oio.de/web-dynpro-the-new-sap-face.htm

14 - wd_dataflow context mapping and model binding

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