The set of C functions in OpenAPI enable an application to connect to a DBMS Server, execute SQL statements, and retrieve results. It provides support for all Ingres SQL statements. OpenAPI also lets an application connect to the Name Server and execute Name Server query statements.

OpenAPI is an interface that currently resides on top of the Ingres client/server protocol, called the General Communications Architecture (GCA). By using the GCA protocol, OpenAPI can communicate with the following: