Information Technology Reference
In-Depth Information
Indirectly related class: The constraint involves the navigation of a series of
associations to an indirectly related class.
All of the constraints can be built using a combination of these three basic cases
of navigation that are listed below. Once we know how to deal with these cases of
navigation, we can build any constraint.
• OCL sets are used when navigating a single association.
• OCL sequences are used when navigating a single ordered association.
• OCL bags are multisets: they can contain he same object multiple times. Bags
are used to accumulate the objects when accessing indirectly related objects
(Bruegge and Dutiot
2004
).
8.5.4 OCL Quantifiers
There are two operations on collections which enable us to iterate over collections
and test expressions on each element:
1. Forall (variable| expression) is true if expression is true for all elements in the
collection.
2. Exists (variable| expression) is true if there exists at least one element in the
collection for which expression is true (Bruegge and Dutiot
2004
).
8.6 Managing Object Design
There are two primary management challenges during object design. The first
challenge is an increased communication complexity: The number of participants
involved during this phase of development increases dramatically. The object
design models and code are the result of the collaboration of many people.
Management needs to ensure that decisions among these developers are made
consistently with project goals. The second challenge is the consistency with prior
decisions and documents: Developers often do not appreciate completely the
consequences of analysis and system design decisions before object design. When
detailing and refining the object design model, developers may question some of
these decisions and reevaluate. The management challenge is to make sure all
documents reflect the current state of development (Bruegge and Dutiot
2004
).
8.6.1 Documenting Object Design
The first section of the ODD is an introduction to the document. It describes the
general
trade-offs
made
by
developers,
guidelines
and
conventions,
and
an
