API processor The API processor is essentially just the public interface to the DBMS made available through an API. In this way, database applications may be written directly in the host language making use of the DBMS services by invoking the functions in the API. In some cases, the API allows the database application to contain embedded DDL or DML statements. These statements are handled by the API through the language processor. Language processor The language processor is the pre-processor, parser, and compiler for the DDL and DML languages.