Software Engineering

2. 
Modifiability
, which addresses the ease with which the architecture can accom-
modate changes (product support).
3. 
Testability
, which addresses the ease with which the software product can be 
demonstrated to satisfy its specifications and stakeholder’s needs (acceptance 
testing).
4. 
Usability
, which is the ease of use and training of end users (training). Each of 
these attributes directly impacts a software life-cycle concern and total life-cycle 
costs.
The evaluation of implementing a desired change proposal must determine the 
impact of the change on the engineering solution, represented by the software prod-
uct architecture. If the architecture has been designed to be modifiable, then the 
effect on the architecture may not be substantial. Assuming the architecture and its 
documentation have been kept current, then it should be relatively simple to iden-
tify the design alterations that must be accomplished to affect the proposed change. 
This mandates the need for extensive traceability among the software architecture 
elements and project control mechanisms.
The software architecture and its documentation and relationships to work pack-
ages facilitates the incorporation of proposed changes into the software product 
and plans. However, every change implementation affects the progress of the pro-
ject as staff effort is diverted from planned activities to revise the product archi-
tecture, documentation, and plans. The impact analysis must account for progress 
1 
See 
http://www.softwarearchitectures.com/go/Discipline/DesigningArchitecture/QualityAttributes/tabid/ 
64/Default.aspx
.

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