Chapter 3 Building Process Hierarchy Diagrams

Process Hierarchy Diagram Basics

A Process Hierarchy Diagram (PHD), sometimes known as a Functional Decomposition Diagram (FDD), is an optional diagram in a BPM, which lets you specify the structure of a system by identifying high-level functions independently of their execution order or conditions. In the PHD you decompose processes to an appropriate level of detail in order to understand the functions required by your system. This process decomposition is called a process hierarchy. All the processes are related to each other by decomposition links. During the creation of your diagram, you can move or reuse processes as necessary.

The PHD is mostly used during the analysis phase of a project. Business analysts and managers use it to:

Define all the processes performed in the scope of a business function
Focus on process recognition and enumeration; only process names are defined at this step
Decompose already identified processes into sub-processes until an appropriate atomic level is reached
Reorganize sub-processes, if necessary, by changing their parent
Display in a single view the whole hierarchy of an already described process or of any decomposed sub-process

Example

In the following example, the root process, Marketing, is decomposed into three sub-processes, Paper Advertising, Email Campaign, and Corporate Web Site. The latter is in turn decomposed into two sub-processes, and so on:

Each of these processes can be analyzed in its own business process diagram (see the Building Business Process Diagrams chapter).