The Beas service layer is a middle layer between the application and the database.
The Beas service layer is a new generation of extension API for consuming Beas and SAP Business One data and services.
It builds on a core protocol, such as HTTP and OData, but you can also use it with Beas script, macro script, or PowerBuilder.
BSL provides a uniform way to expose full-feature business objects on top of highly scalable, high-availability applications.
Service layer currently supports OData versions 2, 3 and 4 (with limited compatibility).
For more information see BSL Documentation