A nice feature of the Ellucian Banner product is the large variety of PL/SQL packages available for use by the customer. These constitute an API. Rather than having to manually track database table schema changes, ensure referential integrity, etc. on a case-by-case basis, client code can simply call the API and get the desired result without hassle.
Ellucian also provides a smaller set of Java and Web APIs, as well, depending on the product. It also has an event-driven architecture called Banner Event Publisher.
Long-term, Ellucian intends to migrate the INB and SSB user interfaces to Banner XE, a system based on Groovy-on-Grails. The intention is to make all service-oriented calls available at the Web service level, for use by XE as well as external applications. However, there is a fallback position available for having Groovy call the traditional PL/SQL packages should porting them to Java be problematic (slow, too expensive, etc.).