Best Practices in development of Business Classes in OO ABAP

Leonardo De Araujo

Alexandre Giguere

Agenda

What are Business classes ?

Why do we need them ?

Development standards

Examples

How to use them

DEMO

Next Steps

What are business classes?

OO ABAP Classes that represent business objects (ex: Purchase order, Sales Order, Delivery, Material, etc);

Largely based on SAP content, but not restricted to it (you can have classes for your own objects);

Best Practices in development of Business Classes in OO ABAP

Why do we need Business Classes?

Reduce TCO via standards, reusability, simpler coding and support;

Meaningful representation of SAP programs;

OO ABAP implementation;

MVC support. Business classes = Model;

Why do we need Business Classes? (cont.)

(Reasons why Object oriented approach achieves higher reliability)

Code abstraction makes it easier the communication between the functional and the technical team;

Reusability guarantees that the same logic is not coded in many places what could make it harder to maintain them in sync and potentially produce different results in different programs;

Encapsulation makes the solution more robust;

Classical Approach Business Requirement Development Objects Programs Tables Screens Example: Need a program to release a PO and create an inbound delivery for it. How to spec it? Where do I start the development?

Object Oriented Approach Business Requirement Development Objects Example: Need a program to release a PO and create an inbound delivery for it. CLASS ZCL_PURCHASE_ORDER Method RELEASE Method CREATE_DELIVERY

Development Standards

Naming convention;

Instantiation;

Buffering / performance optimization;

Inheritance;

Utility Classes;

Exception classes utilization;

Model Class;

Package Hierarchy;

Naming convention - General

Use English names

Use glossary terms

In compound names, use the underscore as separator

Naming convention - Attributes

Key Attribute – Instance Public (ONLY!); ex: Number(vbeln)

Attribute HEADER (if applicable) – Instance Private; ex: VBAK

Attribute ITEMS (if applicable) – Instance Private; ex: VBAP

Other options (SCHEDULE LINES, PARTNERS, etc…)

No need to prefix (ex: GS_HEADER)

For constants; use prefix CO_

Naming convention - Methods

Method names should begin with a verb;

Methods that return a boolean should begin by IS_

Event handler methods should begin with ON_

Method that verify of validate a state should begin by CHECK_

Events name should have the form noun_participle

Recommended methods parameters

IM_ for IMporting parameters

EX_ for EXporting parameters

CH_ for CHanging parameters

RE_ for REturning parameters

Naming convention – Methods (cont.)

Public

Method READ – Static Public;

Method DISPLAY – Instance Public;

Method GET_ <<attrib>> – Instance public;

Lifecycle methods CRUD (Create, Read, Update and Delete)

Protected / Private

Method READ_ <<attrib>> – Instance Private;

Method CONSTRUCTOR – Instance Private;

Instantiation

Instantiation as Private or Protected. NOT PUBLIC ;

Provide methods to instantiate your BC

Search

Read / Factory

Example:

PARAMETERS pa_vbeln TYPE vbeln_vl OBLIGATORY.

DATA lo_delivery TYPE REF TO zcl_outbound_delivery.

lo_delivery = zcl_outbound_delivery=>read( pa_vbeln ).

Buffering / performance optimization

Leveraging READ method to improve performance via buffering;

Attribute BUFFERED_OBJECTS (Public Static) of type table of the following structure:

KEY type <<TYPE OF THE KEY OF THE OBJECT>>

DATA type ref to <<CLASS ITSELF>>

READ method checks buffer before instantiation;

READ method updates buffer after instantiation;

Buffering / performance optimization (cont.)

Method READ.

Data: wa_buffered_obj type <<< >>>.

Read table BUFFERED_OBJECTS with key KEY = INPUT

into wa_buffered_obj <<binary search>>.

If sy-subrc eq 0.

Return = wa_buffered_obj-data.

Else.

Create object Return

exporting

key = INPUT.

wa_buffered_obj-key = Return-key.

wa_buffered_obj-data = Return.

Apppend wa_buffered_obj to buffered_obj.

Endif.

Endmethod READ.

** PS. FREE_ALL( ) or optional parameter bypass_buffer

Inheritance

ZCL_PURCHASEORDER

Attributes:

NUMBER

HEADER (EKKO)

ITEMS (EKPO)

INBOUND DELIVERIES

Methods:

CREATE

READ

FLAG_FOR_DELETION

SIMULATE_DISTRIBUTION

CREATE_DELIVERY

ZCL_MMDOCUMENT

Attributes:

NUMBER

HEADER (EKKO)

ITEMS (EKPO)

Methods:

CREATE

READ

FLAG_FOR_DELETION

ZCL_STO

Attributes:

NUMBER

HEADER (EKKO)

ITEMS (EKPO)

OUTBOUND DELIVERIES

Methods:

CREATE

READ

FLAG_FOR_DELETION

SIMULATE_DISTRIBUTION

CREATE_DELIVERY

Utility Classes (UC)

Main Advantages:

Implement OO

Build once and used everywhere

Examples:

ZCL_FTP (for File Transfer Protocol)

ZCL_APPLICATION_LOG (for Business Application Log)

ZCL_ADDRESS (for Business Address Repository)

ZCL_EMAIL (for Business Communication Service)

ZCL_BDC (for Batch Data Communication)

Class-Based Exceptions

Introduced as of BASIS release 6.10

Created using the Class Builder (SE24)

Derived from the predefined basic classes:

CX_STATIC_CHECK (recommended)

CX_DYNAMIC_CHECK REVIEW BY ALEX

CX_NO_CHECK REVIEW BY ALEX

Exception Text Management

Online Text Repository

Message Class (recommended)

Class-Based Exceptions (cont.)

Have your own EC linked to your BC (1:1 if applicable)

Example:

ZCL_OUTBOUND_DELIVERY (Business Class)

ZCX_OUTBOUND_DELIVERY (Exception Class)

Assign a Message Class to the EC (1:n)

Example:

Z_LE_SHP_DL (for Delivery Processing)

Class-Based Exceptions (cont.)

Attributes

Define KEY attributes of the business class

Flag public attributes as read-only

BAPIRET2_T (if applicable)

Methods

Log & display exception messages into the BAL

Display exception messages for RF screen limitations using SAP Console.

Model Class (MC)

Build your application logic over a general abstraction layer

Build your MC using:

Utility Class

Business Class

Persistent Class

Exception Class

Use the assistance class as your model for WD4A

Examples:

ZCL_DISTRIBUTION (for Distribution …)

ZCL_PICKING (for Picking …)

ZCL_PACKING (for Packing Station …)

Package Hierarchy

Examples

Business Classes in SAP ERP:

ZCL_SALES_ORDER

ZCL_PURCHASE_ORDER

ZCL_PURCHASE_REQUISITION

ZCL_CUSTOMER

ZCL_VENDOR

ZCL_MATERIAL

ZCL_HANDLING_UNIT

ZCL_STORAGE_UNIT

ZCL_TRANSFER_ORDER

ZCL_SHIPMENT

ZCL_MATERIAL_DOCUMENT

ZCL_INBOUND_DELIVERY

ZCL_OUTBOUND_DELIVERY

ZCL_ALLOCATION_TABLE

…

How to use them – Exemple 2 – Process flow

Report ZZZTEST123.

Parameters: p_order type vbeln.

Data: o_order type zcl_salesorder,

o_del type zcl_outbounddelivery.

...

* Read instance of the sales order

o_order = zcl_salesorder=>read( p_order ).

* Create delivery, returning instance

o_del = o_order->deliver( ).

* Post GI for delivery

o_del->post_GI( ).

...

Method deliver. (class zcl_salesorder) ... r_del = zcl_outbounddelivery=>create( key ) ... Endmethod.

DEMO

Next Steps

Consolidation of community standard

Wizard for automation of class generation

For more information:

SAP-PRESS Releases

Next Generation ABAP Development

ABAP Objects: ABAP Programming in SAP NetWeaver

SAP TechEd 2008 Sessions

COMP275 – Modern Business Programming with ABAP Objects

COMP277 – ABAP Development: Update Your Skills to SAP NetWeaver 7.0

SAP Links

http://www.sdn.sap.com

http://help.sap.com

Best Practices in development of Business Classes in OO ABAP

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