Page 229 - DCAP405_SOFTWARE_ENGINEERING

Software Engineering

Notes Requirements Classification

Requirements can be classified on a number of dimensions:
Figure 13.2: Requirement types

Client managers
System end-users
User requirements Client engineers
Contractor managers
System architects

System end-users
Client engineers
System requirements
System architects
Software developers

Client engineers
Software design (perhaps)
specification System architects
Software developers

Other classifications may be appropriate, depending upon the organization’s usual practice and
the application itself.
There is a sturdy overlap between requirements classification and requirements attributes.

Conceptual Modeling

The growth of models of a real-world problem is key to software requirements analysis. Their
purpose is to aid in understanding the problem, rather than to initiate design of the solution.
Hence, conceptual models comprise models of entities from the problem domain configured to
reflect their real-world relationships and dependencies. Several kinds of models can be developed.
These include data and control flows, state models, event traces, user interactions, object models,
data models, and many others. The factors that influence the choice of model include
The nature of the problem. Some types of software demand that certain aspects be analyzed
particularly rigorously.

Example: Control flow and state models are likely to be more important for real-time
software than for management information software, while it would usually be the opposite for
data models.

The expertise of the software engineer. It is often more productive to adopt a modeling
notation or method with which the software engineer has experience.

The process requirements of the customer. Customers may impose their favored notation
or method, or prohibit any with which they are unfamiliar. This factor can conflict with
the previous factor.
The availability of methods and tools. Notations or methods which are poorly supported
by training and tools may not achieve widespread acceptance even if they are suited to
particular types of problems.

222 LOVELY PROFESSIONAL UNIVERSITY