Operation contracts provide a pre-condition and post-condition format to precisely describe changes to objects in a domain model resulting from a system operation, serving as a more detailed specification than typical use cases. An operation contract defines the operation name and parameters, references relevant use cases, assumptions about the system state before execution, and importantly describes the resulting state of domain model objects after completion. Operation contracts are optional in the Unified Process and should only be used when use cases are insufficient for developers to understand system behavior.

1. 8. Operation Contracts
Fakultas Ilmu Komputer
Universitas Sriwijaya
2008

2. Introduction
• Use cases or system features
are the main ways in the UP to
describe system behavior, and
are usually sufficient. Sometimes
a more detailed or precise
description of system behavior
has value. Operation contracts
use a pre- and post-condition
form to describe detailed
changes to objects in a domain
model, as the result of a system
operation.

3. UP Artifact Influence

4. Example

5. Definition
• Operation:
Name of operation, and parameters
• Cross References:
Use cases this operation can occur within
• Preconditions:
Noteworthy assumptions about the state of the
system or objects in the Domain Model before
execution of the operation. These are non-trivial
assumptions the reader should be told.
• Postconditions:
This is the most important section. The state of
objects in the Domain Model after completion
of the operation. Discussed in detail in a
following section.

6. What is a System Operation?

7. If developers can
comfortably understand
what to do without them,
then avoid writing
contracts….!