System development is the development of an information system. System is a set of components that interact to achieve a common goal. System development should involve representatives from each department in which the proposed system will be used.
Information system is a collection of hardware, software, data, people and procedures that work together to produce quality information.
There are 5 phases in system development life cycle:
- Planning
- Analysis
- Implementation
- Maintenance
General guidelines for system development:
- Group activities or task into phases.
- Involve users.
- Define standards.
Project management- process of planning, scheduling and controlling the activities during system development.
Analysis of project management:
- Project scope.
- Required activities.
- Time estimates for each activities.
- Cost estimates for each activities.
- Order of activities.
- Activities that can take place at the same time.
Feasibility- measure of how suitable the development of system will be to the organisation.
- Operational feasibility
- Schedule feasibility
- Technical feasibility
- Economic feasibility
Documentation- the collection and summarisation of data and information.
How data and information gathered?
- Review documentation.
- Observe.
- Survey.
- Interview.
- JAD (Joint Application Design) session.
- Research.
(1)The planning phase for a project begins when the steering committee receives a project request.
Four major activities are performed:
- Review and approve project requests.
- Prioritize the project requests.
- Allocate resources.
- Form a project development team.
(2)The analysis phase consists of two major activities:
- Conduct a preliminary investigation
- Perform detailed analysis
Process modeling (structured analysis and design) is an analysis and design technique that describes processes that transform inputs into outputs.
- Entity-relationship diagrams
- Data flow diagrams
- Project dictionary
An entity-relationship diagram (ERD) is a tool that graphically shows the connections among entities in a system
Entities are objects in the system that have data.
A data flow diagram (DFD) is a tool that graphically shows the flow of data in a system.
- Data flows
- Processes
- Data stores
- Sources
The project dictionary contains all the documentation and deliverables of a project
Structured English is a style of writing that describes the steps in a process
(3) The design phase consists of two major activities
- Acquire hardware and software
- Develop all of the details of the new or modified information system
The next step is to develop detailed design specifications
Sometimes called a physical design
- Database design
- Input and output design
- Program design
A prototype (proof of concept) is a working model of the proposed system
- Prototypes have inadequate or missing documentation
- Users tend to embrace the prototype as a final system
- Should not eliminate or replace activities
Computer-aided Software Engineering (CASE)- tools that are designed to support one or more activities of system development.
- Project repository.
- Graphics.
- Prototyping.
- Quality assurance.
- Code generator.
- Housekeeping.
(4) The purpose of the implementation phase is to construct the new or modified system and then deliver it.
- Develop programs
- Install and test the new system
- Train users
- Convert to the new system
Program Development Cycle
- Analyze requirements
- Design the solution
- Validate the design
- Implemetn the design
- Test the solution
- Document the solution
(5) Maintenance
- Perform maintenance activities- to maintain the lifetime of the system.
- Monitor system performance- to see if any improvement is needed.
- Assess system security- manage the security and keep it updated.
Computer security plan should have:
- Identify all information assets of an organisation.
- Identify all security risks that may cause an information asset loss.
- For each risk, identify the safeguards that exist to detect, prevent and recover from a loss.
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