Enterprise Service Layer

The Enterprise Service Layer (ESL) is the highest level of abstraction in a SOA architecture.

An API defined at ESL can cross domain boundaries; it calls directly the Domain Service Layer, which in turn interacts with the Application Service Layer or the RDBMS Service Layer.

Since the ESL is the API of the enterprise, all the components in the enterprise can call it directly.

ESL exposes a number of API considerably lower than the ASL because it works at a higher level of abstraction than the ASL.