This section describes ways in which you can expose your application's business logic functionality encapsulated within your Service layer.
Note
In some cases, Developer X is able to achieve such functionality through the standard Salesforce APIs. However, depending on the requirement, it might be easier and safer to call an API that exposes an existing business logic within the application. You can decide to do this for the same reasoning you would create a custom Visualforce page rather than expect the end users to utilize solely the standard UI (as using your objects directly requires them to understand the application's object schema in more detail).