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Buffering is available under Technical Settings in SE11.
Buffering has 3 options.
SAP buffering can be permitted for a database table as follows:
Buffering not allowed
SAP buffering is not performed for the table. Open SQL always accesses the current data of the data table directly. This setting also dictates that SAP buffering should also not be activated for this table in any other systems due to the way it is used.
Buffering allowed, but switched off
SAP buffering is not performed for the table when delivered. This setting dictates, however, that buffering is possible in principle and can be activated in other systems depending on how the table is used.
Buffering switched on
SAP buffering is performed for the table. If possible, Open SQL statements access the SAP buffer in the shared memory instead of accessing the table directly.
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BAPI and RFC enabled FM are similar however, since BAPI is registered in BOR, it can be accessed through external applications and languages like VBA Excel or other places. RFC enabled FM works for SAP to SAP type systems
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"This variant of the statement CLASS is used to make the class class known, regardless of the location of the actual definition of the class in the program. It does not introduce a declaration part and must not be ended using ENDCLASS.

Example: CLASS c1 DEFINITION DEFERRED.
One example of using the addition DEFERRED PUBLIC would be a type group in which a reference type is declared with a reference to a global class, which itself contains components with references to this reference type. In this situation, the entire class cannot be loaded before the type group, since the types are not yet known. After the statement DEFERRED PUBLIC, however, the class name can be specified after REF TO without the class having been loaded previously."