Page 91 - DCAP405_SOFTWARE_ENGINEERING

Software Engineering

Notes Creation of a document describing the external behavior and associated constraints that
will satisfy those needs.

Analysis and validation of the requirements document to ensure consistency, completeness
and feasibility.
Evolution of needs.
The primary output of requirements engineering is requirements specification. If it describes
both hardware and software it is a system requirement and if it describes only software
requirement it is a software requirements specification. In both these cases, the system is treated
as a black box.
Requirements Specification

Requirements specification can be done in the form of a document, graphical model, prototype
or a combination of all these. System specification can be elicited using a standard template or
a flexible approach depending upon the system being developed.

System specification is produced as a result of system and requirements engineering. It contains
details about the hardware, software, database etc. It describes both the function and constraints
required for developing a system. It also tells about the input and output information from the
system.

Requirements Validation

The work product produced as a result of requirements engineering is checked for quality
during the validation step. Requirements validation ensures that all the requirements have
been stated correctly, inconsistencies and errors have been detected and corrected and that the
work product conforms to the standard for process, project and product.
Although the requirements validation can be done in any way that leads to discovery of errors,
the requirements can be examined against a checklist. Some of the checklist questions can be:

Are the requirements clear or they can be misinterpreted?
Is the source of the requirements identified?
Has the final statement of requirement been verified against the source?
Is the requirement quantitatively bounded?
Is the requirement testable?
Does the requirement violate domain constraints?
These questions and their likes ensure that validation team does everything possible for a
thorough review.

Requirements Management

Requirements may change throughout the life of a computer based system. Requirements
management includes the activities that help a project team to identify, control and track
requirements and changes to these requirements at any time during the project.
Requirements management begins with identification. Once the requirements have been
identified traceability tables are created. This table relates each requirement to one or more
aspects of system or its environment. They may be at times used as a requirements database in
order to understand how a change in one requirement will affect other aspects of the system
being built.

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