The top-down approach focuses on the overall process. It starts with defining the overall business requirements that give the framework of the business process model. After that the model that describes how a requirement is fulfilled is split to separate business processes. Each of these processes has its specific activities and the activities include on their side specific services and tasks. The goal of the model, however, is to depict a broader view of a business process fulfilling a given requirement but not to show how a specific activity is performed. This broader view helps business analysts and managers to see how the overall process goes, where it needs improvements, and whether any elements are missing in the general process. On the other side, a top-down process model that does not focus on the subprocesses' characteristics and activities does not allow to see how the subprocesses and their activities behave in reality.
In the process composer, you can use the top-down approach to model a process according to the requirements of a specific business case. The starting point is defining a general overview of the process and the process steps. With this approach, the process modeling includes the following steps:
Creating a process.
Creating the process steps, represented by activities (human, automated, subprocess).
Creating and importing the business logic of the process steps (tasks, Web services, rules).