Learning Domain-Driven Design

Chapter 3. Managing Domain Complexity

As you saw in the previous chapter, to ensure a project’s success it’s crucial that you develop a ubiquitous language that can be used for communication by all stakeholders, from software engineers to domain experts. The language should reflect the domain experts’ mental models of the business domain’s inner workings and underlying principles.

Since our goal is to use ubiquitous language to drive software design decisions, the language must be clear and consistent. It should be free of ambiguity, implicit assumptions, and extraneous details. However, on an organizational scale, the domain experts’ mental models can be inconsistent themselves. Different domain experts can use different models of the same business domain. Let’s take a look at an example.

Inconsistent Models

Let’s go back to the example of a telemarketing company from Chapter 2. The company’s marketing department generates leads through online advertisements. Its sales department is in charge of soliciting prospective customers to buy its products or services, a chain that is shown in Figure 3-1.

Figure 3-1. Example business domain: telemarketing company

An examination of the domain experts’ language reveals a peculiar observation. The term lead has different meanings in the marketing and sales departments:

Marketing department

For the marketing people, a lead represents a ...