The most important phase in the SDLC process is to determine system requirements. If the requirements are wrong, the system will be wrong. SIX activities occur in this phase as the diagram shows. Users are a critical part of this phase. They must approve the requirements before moving to the next phase.
At this stage the system analyst must come up with the detailed requirements for the new system. Some of these requirement specifications include:
1. Output Specifications
These are the expected results from our proposed system.
The following factors should be considered when designing the output;
2. Input Specifications
We need to identify the input needed to obtain the relevant information from the system.
3. •File/Data Stores
This involves making informed decisions on files required to store data and information in the system. The attributes of the records in a file should also be identified. An attribute is a unique characteristic of a record for which a data value can be stored in the system database.
Factors to consider when designing a file:
4. Hardware and Software Requirements
The system analyst should specify all hardware and software requirements for the new system. Some of the factors to consider in hardware and software specification are:
Flowcharts use special shapes to represent different types of actions or steps in a process. Below are some of the shapes most commonly used;
Guidelines for drawing a system Flowchart
Stage 5: System Construction
By the end of the topic, the learner should be able to:
a) describe a system.
b) define an information system.
c) state the purpose of an information system.
d) identify the stages of system development.
e) develop a system using a case study.
f) write a report on the case study.
9.0.0 SYSTEM DEVELOPMENT (44 LESSONS)
9.2.1 Description of a system.
9.2.2 Definition of an Information system.
9.2.3 Purpose of an Information System.
9.2.4 Stages of system development
9.2.5 System Documentation
Langat, J., Musonye, D., & Antony, W. (2008). Foundation Computer Studies Book 3. In J. Langat, D. Musonye, & W. Antony, Foundation Computer Studies Book 3 (Pp. 74-110). Nairobi: Jomo Kenyatta Foundation.
Mburu, S., & Chemwa, G. (2013). Longhorn Secondary Computer Studies. In S. Mburu, & G. Chemwa, Longhorn Secondary Computer Studies (Pp. 91-120). Nairobi: Longhorn Publishers (K) Ltd.
Sommerville, I. (2010). Documentation. Retrieved 03 2017, From Host.Cs.St-Andrews:Https://Ifs.Host.Cs.St-Andrews.Ac.Uk/Books/Se9/Web/Extrachaps/ Documentation.Pdf
System Development definition
System development can be defined in various ways such as:
What is a system?
Description of a System.
A system can be described as either:
A system is described as soft because of the following characteristics:
A system is said to be hard because of the following characteristics:
Characteristics of Systems
All systems have some similar characteristics as illustrated below:
1. Holistic thinking
A system is considered as a whole because many entities will work together to make a complex whole.
A system is made up of different components (subsystems)
3. Boundary and Environment
Each system has a space or boundary within which the components operate. A system has two types of entities namely: internal and external entities.
An internal entity operates from within the system boundary. However, External entities operate from outside the boundary but are part of the system.
The purpose of each system is to perform a particular task or achieve a goal.
A system has the obligation to transform or process data from one state to another
6. System Entropy
The word entropy means decay. Systems decay over time.
7. Inputs and Outputs
A system communicates with environment by receiving inputs and giving outputs
8: Open VS Closed Systems
A system can be described as either open or closed. An open system receives input and gives output while a closed system does not.
A system adapts to changes in the environment in order to give the expected output or to perform to the expected level. This is possible through the feedback which can be used to influence inputs
Purpose of Information Systems
METHODS OF DEVELOPING SYSTEMS
There are four system development processes that help make projects more likely to succeed.
Each of these development methods offers advantages based on the scope and complexity of the system being built. No single process works for all projects because the scale of systems varies widely and different processes are appropriate for different types of systems.
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