BAPI Conventions ABAP Interview Questions

BAPI Conventions

Methods

• If the BAPI to be implemented is a standardized BAPI, use the generic names, for example, GetList, GetDetail.
• The method name must be in English (maximum 30 characters).
• The individual components of a BAPI name are separated by the use of upper and lower case.Example: GetList
  Underscores ("_") are not allowed in BAPI names.
• Each BAPI has a return parameter that is either an export parameter or an export table.
• So that customers can enhance BAPIs, each BAPI must have an ExtensionIn and an ExtensionOut parameter.

Parameters

• If standardized parameters are used, you have to use the names specified for standardized parameters.
• BAPI parameter names should be as meaningful as possible. Poorly chosen names include abbreviations and technical names (e.g. "flag", table names, etc.).
  The parameter and field names must be in English with a maximum of 30 characters.
• The components of a parameter name in the BOR are separated by upper and lower case letters to make them easier to read. Example: CompanyCodeDetail
• Values that belong to each other semantically should be grouped together in one structured parameter, instead of using several scalar parameters.
• For ISO-relevant fields (country, language, unit of measure, currency), additional fields for ISO codes are provided.
• Unit of measure fields must accompany all quantity fields and currency identifiers must accompany currency amount fields.

Standardized BAPIs

Some BAPIs provide basic functions and can be used for most SAP business object types. These BAPIs should be implemented the same for all business object types. Standardized BAPIs are easier to use and prevent users having to deal with a number of different BAPIs. Whenever possible, a standardized BAPI must be used in preference to an individual BAPI.

The following standardized BAPIs are provided:

Reading instances of SAP business objects

GetList ( )	With the BAPI GetList you can select a range of object key values, for example, company codes and material numbers. The BAPI GetList() is a class method.
GetDetail()	With the BAPI GetDetail() the details of an instance of a business object type are retrieved and returned to the calling program. The instance is identified via its key. The BAPI GetDetail() is an instance method.

BAPIs that can create, change or delete instances of a business object type

The following BAPIs of the same object type have to be programmed so that they can be called several times within one transaction. For example, if, after sales order 1 has been created, a second sales order 2 is created in the same transaction, the second BAPI call must not affect the consistency of the sales order 2. After completing the transaction with a COMMIT WORK, both the orders are saved consistently in the database.

Create( ) and CreateFromData( )	The BAPIs Create() and CreateFromData() create an instance of an SAP business object type, for example, a purchase order. These BAPIs are class methods.
Change( )	The BAPI Change() changes an existing instance of an SAP business object type, for example, a purchase order. The BAPI Change () is an instance method.
Delete( ) and Undelete( )	The BAPI Delete() deletes an instance of an SAP business object type from the database or sets a deletion flag. The BAPI Undelete() removes a deletion flag. These BAPIs are instance methods.
Cancel ( )	Unlike the BAPI Delete(), the BAPI Cancel() cancels an instance of a business object type. The instance to be cancelled remains in the database and an additional instance is created and this is the one that is actually canceled. The Cancel() BAPI is an instance method.
Add ( ) and Remove ( )	The BAPI Add adds a subobject to an existing object instance and the BAPI and Remove removes a subobject from an object instance. These BAPIs are instance methods.

BAPIs for Mass Data Processing

The BAPIs listed above for creating and changing data can also be used for mass processing. For more information see BAPIs for Mass Data Transfer [Extern]

BAPIs for Replicating Business Object Instances

Replicate( ) and SaveReplica( )

The BAPIs Replicate() and SaveReplica() are implemented as methods of replicable business object types. They enable specific instances of an object type to be copied to one or more different systems. These BAPIs are used mainly to transfer data between distributed systems within the context of Application Link Enabling (ALE). These BAPIs are class methods.

Other Less Used Standardized BAPIs

• Programming GetStatus() BAPIs [Extern]
• Programming ExistenceCheck() BAPIs [Extern]

Standardized Parameters

There are some parameters that can be created for various BAPIs because they contain the same or the equivalent data in all BAPIs. They should be implemented the same in all BAPIs.

Address parameters	Specific reference structures are defined for address parameters in BAPIs. You should copy these structures to use in your BAPI, especially if the underlying object type uses the central address management (CAM).
Change Parameters	In BAPIs that cause database changes (for example, Change() and Create() BAPIs) you must be able to distinguish between parameter fields that contain modified values and parameter fields that have not been modified. This distinction is made through the use of standardized parameters.
Extension parameters	The parameters ExtensionIn and ExtensionOut provides customers with a mechanism that enables BAPIs to be enhanced without modifications.
Return Parameters	Each BAPI must have an export return parameter for returning messages to the calling application. To provide application programmers with a consistent error handling process for BAPI calls, all return parameters must be implemented in the same, standardized way.
Selection Parameters	Standardized selection parameters are used in BAPIs that can be used to search for specific instances of a business object type (e.g. in GetList() ). These parameters enable the BAPI caller to specify the relevant selection criteria.
Test Run Parameters	The parameter TestRun is used in write BAPIs (Create() and Change() ), to check the entries for the object instance in the database before actually creating the object instance. The creation of the object instance is only simulated and data is not updated.
Text Transfer Parameters	To transfer BAPI documentation texts (e.g. the documentation of a business object type), you have to create standardized text transfer parameters.

Important things to remember..

It is important to follow the guidelines below when develop9ng BAPIs:

• BAPIs must not contain CALL TRANSACTIO or SUBMIT REPORT
• BAPIs must not invoke a COMMIT WORK. instead use the BAPI TransactionCommit to execute the commit after the BAPI has executed.
• BAPI structures must not use includes.
• There should be no functional dependecies between two BAPIs
• BAPIs must perform there own authorization check
• BAPIs should not use dialogs
• BAPIs must not cause the program to abort or terminate. re4levant messages must be communicated through the return parameter.

BAPI/ALE Integration

When you use the BAPIs for asynchronous messagning, the application in the sendig systen calls the generated ALE IDoc interface isntead of the BAPI.

Asynchronous BAPIs use the ALE interface this way:

• Creates an IDOC from the BAPI data
• Sends the IDOC to the target system
• Receives the IDOC in trhe target system, crreates the BAPI data from the IDoc and calls the BAPI

An ALE interface for a BAPi is created in transaction BDBG.