A domain model can provide compact information about its corresponding software system for business people. If the software system exists without its domain model and documentation it is time-consuming to understand its behavior and structure only from the code. Reverse Engineering (RE) tools can be used for obtaining behavior and structure of the software system from source code. After that the domain model can be created. A short overview and an example of obtaining the domain model, Topological Functioning Model (TFM), from source code are provided in the paper. Positive and negative effects of the process of TFM backward derivation are also discussed.