This section describes ways in which you can expose your application's business logic functionality that's encapsulated within your Service layer.
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 existing business logic within the application. You can decide to do this for the same reason you would create a custom UI rather than expect the end users to solely utilize the standard UI (because using your objects directly requires them to understand the application's object schema in more detail).
