Information Technology Reference
In-Depth Information
Chapter 7
System Design
System design involves a process to fulfill user requirements. Constraints imposed
on the project and on the user requirements may interact in complex ways to
produce several designs rather than a single design. The result of the design phase
is several system design deliverables as a design report which is ready for eval-
uation. System design as described by Sommerville is concerned with how the
system functionality is to be provided by different components of the system. The
activities in the process are (Sommerville
1996
):
• Partition requirements: During this phase requirements are analyzed and formed
into groups.
• Identify sub-systems: This activity is concerned with identifying different sub-
systems which meet the requirements.
• Assign requirements to subsystems: In this phase, the requirements are assigned
to subsystems. In principle there is never a clean match between requirements
partitions and identified sub-systems.
• Specify sub-system functionality: this may be seen as a system design phase or
software system design phase.
• Define sub-system interfaces: This critical activity involves defining the inter-
faces that are provided and expected by each sub-system (Fig.
7.1
).
The system analysis and design phase depend on each other. This Phase of the
SDLC continues from the Detailed System Analysis and describes how the proposed
system will be built. The design is specific to the technical environment that the
system will operate in and the tools used in building the system. The results of this
phase significantly impact the build and implementation phases of the system. The
project manager is responsible for producing the deliverables associated with the
detailed system design. A good system design process should therefore result in a
system which can be implemented in either hardware or software. However, the
project manager usually delegates responsibility for some or all of these deliverables
to the development team. If some or all of the phase's deliverables have been
delegated, the project manager maintains overall responsibility for producing
quality deliverables submitted.
