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148 S o f t w a r e & S y s t e m s R e q u i r e m e n t s E n g i n e e r i n g : I n P r a c t i c e

confused with stability, a property indicating how strong the
consensus is for the current wording of a requirement.
• Impact This explains how the factor is likely to influence
the architecture.
• Authority This is the justification for including the factor in
the analysis. For example, it could be the name of a stakeholder
or a team member, references to requirements, stakeholder
requests, or other project documents, or a phrase like “general
knowledge” or “past experience.” External authorities are
generally better than just listing a team member, but since you
are the architects, others do expect you to be the authority some
of the time. Also, there will be cases where you identify a factor
that you expect will become important to certain stakeholders
later. You can list yourself as the authority temporarily, and
comment on who else may become interested.
• Expert This is the subject matter expert for the factor.
In addition, each factor has other attributes equivalent to those
usually attached to requirements, such as unique ID, owner, status, or
stability.
An example textual description of a factor is given in Figure 5.3.
Although storing factors, issues, and strategies in an ordinary
text document can be adequate for small efforts, we would recommend
managing them with a general-purpose requirements management
tool, such as Teamcenter, Doors, or Requisite Pro, if your organization is
already using one. The key advantage of using a tool is being able to
look at the same text either as a narrative document or as a
requirements catalog.

1. Organizational Constraints
1.3 Management
1.3.5 Buy reporting subsystem
(Factor-37)
The reporting subsystem should be based on a commercial product, e.g. Crystal
Reports
Negotiability Previous reporting system was implemented in-house, so buying
COTS is not a rigid requirement. But competitors are already doing this.
Changeability Reporting features may become more specialized, making the
“buy” option less advantageous.
Impact Buying the market leading product has low development cost, risk, and
time to market, but introduces licensing costs and reduces product
differentiation.
Authority Features 135, 136, and 139, and SR 174 are from Jim Smith, who has
interviewed customers concerning reporting features.
FIGURE 5.3 Textual presentation of a factor