INF3703
(2023)
Contents
CHAPTER 10: ................................................................................................................................................. 1
CHAPTER 11: ............................................................................................................................................... 27
CHAPTER 13: ............................................................................................................................................... 62
CHAPTER 14: ............................................................................................................................................... 74
CHAPTER 15: ............................................................................................................................................... 98
CHAPTER 17: ............................................................................................................................................. 128
T. Booyens
, CHAPTER 10:
10.2.1 Planning:
The planning phase of the SDLC provides a broad overview of the company and its objectives.
Initial assessment during this phase focuses on information flow and extent requirements.
Key questions to answer during the assessment include whether to continue the existing
system, modify it, or replace it.
For continuing the existing system, it's important to evaluate if it's working well and does not
require modification.
Modification may be considered when there are identified deficiencies in information flow.
The distinction between wants and needs is crucial when contemplating system modifications.
Replacing the existing system may be necessary if it has serious flaws beyond fixing.
Evaluating alternative solutions is part of the initial assessment process.
If a new system is deemed necessary, the feasibility study is conducted, addressing technical
aspects, system cost, and operational cost.
Technical aspects involve hardware and software requirements, such as the nature of hardware
and software, and the choice of operating systems, databases, and programming languages.
The system's cost-effectiveness is a crucial consideration, ensuring it aligns with the business
needs.
The operational cost considers human, technical, and financial resources needed to maintain
the system.
The impact of the new system on the company's culture, including potential resistance to
change, is also assessed.
10.2.2 Analysis:
The analysis phase follows the planning phase and involves a detailed examination of defined
problems.
It includes macro analysis of individual and organizational needs, aligning them with overall
information requirements.
The analysis phase serves as an in-depth audit of user requirements.
The existing hardware and software systems are evaluated during this phase to understand
functional areas, problems, and opportunities.
Collaboration between end users and system designers is crucial for identifying processes and
potential issues and setting performance objectives.
A logical systems design is created during this phase, specifying the conceptual data model,
inputs, processes, and expected outputs.
Tools like data flow diagrams (DFDs), hierarchical input process output (HIPO) diagrams, and
entity relationship (ER) diagrams may be used for designing.
Database design activities focus on entities, attributes, and relationships within the database.
Functional descriptions of system components (modules) are developed for each process within
the database environment.
Data transformations (processes) are described and documented using analysis tools like DFDs.
The conceptual data model is validated against these processes.
,10.2.3 Detailed Systems Design:
Detailed systems design phase involves finalizing the design of system processes.
This design includes technical specifications for screens, menus, reports, and other tools to
enhance system efficiency.
The phase outlines steps for transitioning from the old system to the new one.
Principles and methodologies for training are planned and require management's approval.
Management's approval is needed at all stages of the process, as a "GO" decision requires
funding.
There are multiple decision points throughout the process where the project can proceed or
not.
10.2.4 Implementation:
Implementation phase involves installing hardware, DBMS software, and application programs.
It includes a cycle of coding, testing, and debugging until the system is ready for delivery.
The actual database is created, customized with tables, views, user authorizations, and more.
Database contents can be loaded interactively or in batch mode using custom user programs,
database interface programs, or conversion programs.
Exhaustive testing is conducted, traditionally taking up a significant portion of the development
time, but modern tools have reduced this time.
After testing, final documentation is reviewed, printed, and end users are trained.
The system is fully operational at this phase and continually evaluated and fine-tuned.
10.2.5 Maintenance:
The maintenance phase begins shortly after the system becomes operational, as end users
request changes.
System maintenance activities fall into three categories: corrective maintenance for errors,
adaptive maintenance for business environment changes, and perfective maintenance to
enhance the system.
Each request for structural change requires retracing the steps of the SDLC, making the system
always in some stage of the SDLC.
The operational life span of a system depends on its perceived utility, and various factors may
lead to the reduction of this life span, including rapid technological change and high
maintenance costs.
Computer-aided systems engineering (CASe) technology, such as System Architect or Visio
Professional, can aid in producing better systems within a reasonable time and cost.
Structured, well-documented, and standardized implementation of CASE-produced applications
can prolong the operational life of systems by making updates and maintenance easier and
cheaper.
, 10.3 The Database Life Cycle (Dblc):
10.3.1 The Database Initial Study:
The Database Initial Study is initiated when the current system has failed to meet the
company's vital functions.
The database designer needs to assess the current system's operation, determine the
causes of its failure, and communicate with end users to understand their needs and
concerns.
Database design requires strong communication and interpersonal skills, as it is both a
technical and people-oriented task.
Depending on the complexity of the database environment, the designer may work
alone or as part of a systems development team with various roles.
The primary goals of the database initial study are to analyze the company's situation,
identify problems and constraints, define objectives, and set the scope and boundaries
of the project.
The process is interactive and iterative, and it leads to the development of the database
system objectives.
Analyzing the Company Situation:
Understanding the general operational conditions, organizational structure, and mission
of the company.
Aligning the design with the company's mission and operational demands.
Considering operational variations based on the type of business.
Defining Problems and Constraints:
Utilizing formal and informal sources of information.
Analyzing the functioning of the existing system, input requirements, document
generation, and system output usage.
Recognizing the difference between the official system description and real-world
operations.
Addressing challenges in problem definition, particularly in understanding the
operational scope.
Identifying precise answers for effective problem-solving, especially regarding
operational relationships among business units.
Understanding the constraints, such as time, budget, and personnel, that can impact the
design.
