Domain-Driven Design: Tackling Complexity in the Heart of Software

Domain Vision Statement
At the beginning of a project, the model usually doesn't even exist, yet the need to
focus its development is already there. In later stages of development, there is a need
for an explanation of the value of the system that does not require an in-depth study of
the model. Also, the critical aspects of the domain model may span multiple 
BOUNDED
CONTEXTS
, but by definition these distinct models can't be structured to show their
common focus.
Many project teams write "vision statements" for management. The best of these documents lay
out the specific value the application will bring to the organization. Some mention the creation of
the domain model as a strategic asset. Usually the vision statement document is abandoned after
the project gets funding, and it is never used in the actual development process or even read by
the technical staff.
A 
DOMAIN VISION STATEMENT
is modeled after such documents, but it focuses on the nature of the
domain model and how it is valuable to the enterprise. It can be used directly by the management
and technical staff during all phases of development to guide resource allocation, to guide
modeling choices, and to educate team members. If the domain model serves many masters, this
document can show how their interests are balanced.
Therefore:
Write a short description (about one page) of the 
CORE DOMAIN
 and the value it will
bring, the "value proposition." Ignore those aspects that do not distinguish this domain
model from others. Show how the domain model serves and balances diverse interests.
Keep it narrow. Write this statement early and revise it as you gain new insight.
A 
DOMAIN VISION STATEMENT
can be used as a guidepost that keeps the development team headed
in a common direction in the ongoing process of distilling the model and code itself. It can be
shared with nontechnical team members, management, and even customers (except where it
contains proprietary information, of course).

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