B2B Integration : A Practical Guide to Collaborative E-commerce

76 B2B Integration — A Practical Guide to Collaborative E-commerce
Application A Application B
API Calls I I API Calls
Data Access Layer
Data Source Data Source
Figure 3.21. — A typical API call
underlying business logic and data access, providing a higher degree of
security and data integrity.
APIs provide a high-level programming paradigm, where an
application or a program does not execute its own methods or functions
itself but makes some other applications or programs to do it. This way
the actual implementation of the method or function is always delegated
to the program publishing the API and not the calling programs (see
Figure 3.21). If there is any change in the business logic, which requires
changing the implementation of the method, the developers have to
change the code at only one place, i.e., in the program providing the
implementation of the method — as long as the incoming parameters
and output do not change.
For instance, applications and programs developed on any operating
system use APIs provided by the underlying operating system. This way
they are able to delegate all the dirty work of disk Input/Output (I/O),
memory allocation, painting graphics on the monitor, etc., to the operating