In SAP ABAP data migration, what is the main alternative technique to the batch input session method when implementing BDC processing?

Introduction / Context:
Batch Data Communication, or BDC, is a traditional SAP technique for loading data into the system by simulating online transactions. There are two classic approaches: the session method and the CALL TRANSACTION method. Many interview questions ask for the alternative to batch input sessions to check whether the candidate understands both approaches and knows when each one is appropriate.

Given Data / Assumptions:

• BDC is used for migrating or loading data by running SAP transactions programmatically.
• The session method creates batch input sessions that are processed later in background via transaction SM35.
• The CALL TRANSACTION method executes the transaction immediately from the ABAP program using BDC data.
• The question asks specifically for the main alternative to batch input sessions.

Concept / Approach:
In the session method, BDC data is recorded into a session and stored in the database. Administrators then process these sessions as background jobs. In contrast, the CALL TRANSACTION method uses the ABAP statement CALL TRANSACTION with USING bdcdata to run the transaction directly in the program context. This means there is no separate session stored for later; instead the program can evaluate the return messages immediately, log errors, and even handle transaction mode (synchronous, asynchronous, or with update task options). Because of this, CALL TRANSACTION is regarded as the main alternative to the batch input session method.

Step-by-Step Solution:
Step 1: Recall that standard teaching about BDC mentions two main methods: session method and CALL TRANSACTION method. Step 2: Session method writes BDC data to the database as a batch input session, which is later processed in background. Step 3: CALL TRANSACTION method builds BDC data in an internal table and then calls the transaction immediately with that data. Step 4: CALL TRANSACTION allows the programmer to capture messages from the transaction using the MESSAGE control, enabling more granular error handling inside the same ABAP program. Step 5: Option a describes this method accurately and clearly labels it as an alternative to batch input sessions. Step 6: Options b, c, and d describe manual entry or non SAP techniques that are not recognised BDC methods in SAP.

Verification / Alternative check:
You can verify this in SAP documentation and BDC tutorials, which almost always present both the session method and the CALL TRANSACTION method as the two standard approaches. Examples show ABAP code building an internal table bdcdata and then calling CALL TRANSACTION tcod USING bdcdata. Process chains and SM35 processing are only involved in the session method, confirming that CALL TRANSACTION is the named alternative.

Why Other Options Are Wrong:
Option b is wrong because manual keying is not a BDC method; it contradicts the goal of automation. Option c is incorrect and dangerous, as copying database files at the operating system level is not a supported way to migrate application data. Option d refers to printing, which does not update SAP application tables and is unrelated to BDC programming.

Common Pitfalls:
A common pitfall is to always use the session method even for small data volumes where CALL TRANSACTION would be simpler and give better control over error handling. Another mistake is to misuse CALL TRANSACTION in update task modes without understanding the impact on performance and locking. The key takeaway is that session method and CALL TRANSACTION are the two main BDC methods, and CALL TRANSACTION is the direct program driven alternative to batch input sessions.

Final Answer:
Using the CALL TRANSACTION method, where the ABAP program submits transactions online with BDC data in the same session instead of creating separate batch input sessions.