When implementing BAPIs, you should pursue the goal of avoiding the disadvantages of the "postcard effect" associated with conventional interfaces: No separation between contents and transport. In the case of a postcard, the text is written on a card that also serves as the information medium. If the information medium changes, then the receiver has to read the text in a different way. As a result, changes to the interface affect the type of access.

BAPIs, in contrast, clearly separate the business contents from the underlying communication technology. This procedure can be compared to a letter in an envelope: It is easy to put a letter in a new envelope, just like it is easy to apply new and/or different communication technologies like COM/DCOM, the CORBA standard, or new Internet standards. The envelope itself is irrelevant to understanding the contents of the letter. In this example, the BAPIs correspond to the letter, meaning they are independent of the programming language and communication mechanisms used.

Using BAPIs results in the following benefits:

• BAPIs represent well-defined, internally consistent units that always represent business facts and leave a consistent database state behind.

• The business contents can be standardized, since BAPIs not only allow the integration of the SAP system and other software components at a technical level, but also at the business level.

• BAPIs have become a communication standard between business systems. Access is possible through object-oriented interface technologies (such as COM/DCOM from Microsoft). The SAP business objects conform to the guidelines of the OAG (Object Application Group), and meet the CORBA standard from the OMG (Object Management Group).

• Stability and compatibility
  Once SAP has released a BAPI, its interface definitions and parameters will remain stable in the long term, which means application programs will not be affected by changes to the underlying SAP software or data. If upward-compatible enhancements are made to the BAPIs, the stability of the existing applications is not affected.

• Openness
  BAPIs can be accessed from any widespread development platform.