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ICT Class System Life Cycle.  Large systems development projects may involve dozens of people working over several months or even years, so they cannot.

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Presentation on theme: "ICT Class System Life Cycle.  Large systems development projects may involve dozens of people working over several months or even years, so they cannot."— Presentation transcript:

1 ICT Class System Life Cycle

2  Large systems development projects may involve dozens of people working over several months or even years, so they cannot be allowed to proceed in a haphazard fashion.  The goals of an information system must be thoroughly understood and formal procedures and methods applied to ensure that the project is delivered on time and to the required specification.  There are several versions of the systems life cycle diagram; the stages include problems definitions, problem investigation, feasibility study, analysis, design, Most of all the diagrams are by 5 or 6 steps.

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4  The course of developmental changes through which a system passes from its conception to the termination of its use and subsequent salvage, it has 6 steps which are feasibility study, analysis, design, programming, installation and maintenance.

5  The systems life cycle approach to development is also known as the “waterfall model”. The waterfall model is a software development  model describing the naive approach to software development in which development is seen as flowing steadily through the phases of requirements analysis, design, implementation, integration and maintenance

6  The development of a new information system is a major undertaking and not one to be undertaken lightly. For examples stores like Wal-Mart or Target, they have a computerized distribution system in the 80’s, business must adapt to remain competitive. Some of the reasons for introducing this new system may be:  1. The current system may be no longer suitable for its purpose  2. Technological developments may have made the current system redundant or outdated.  3. The current system may be too inflexible or expensive to maintain.

7  Feasibility Study is the first stage of the systems life cycle. The aim of feasibility study is to understand the problem and to determine whether it is worth proceeding. It has 5 main factors that are technical feasibility, economic feasibility, legal feasibility, operational feasibility and schedule feasibility.

8  Investigating what are we doing now  Fact finding methods ◦ Questionnaires ◦ Interviews ◦ Observation ◦ Examining documents  Dataflow diagrams

9  System Design  The design specifies the following aspects of a system:  The hardware, the outputs, the inputs, the user interface, the test strategy, conversion plan, etc.

10  The system specification must describe how the new system will work. Screen layouts and report formats must be designed, file contents and organizations specified, and each program in the system must be described by means of programs specifications, structure charts, pseudo code or flowcharts

11  Prototyping is considered as a strategy in system development in which a scaled down system or portion of a system is constructed in a short time, tested, and improved in several iterations. A prototype is an initial version of a system that is quickly developed to test the effectiveness of the overall design being used to solve a particular problem. Prototyping is similar to the Evolutionary (Iterative) Design Process. It is sometimes termed rapid prototyping and is similar to rapid application development (RAD).

12  The use of structure charts and pseudo codes for describing algorithms. Algorithm is a sequence of instruction to solve a given problem. Pseudo codes is an intermediate stage between plain English and the programming language in which the solution will eventually be coded.

13  Maintainability: The ease with which a software system or component can be modified to correct faults, improve performance or other attributes, or adapt to a changed environment  Usability: will the users find the system easy to use, will it save them time, cut out tedious repetitive tasks, give them quick access to information they need.  Suitability: it integrates an existing software with manual methods that are adapted to a new system  Maintainability: it makes modifications when is required

14  Unit Testing: The type of testing where a developer (usually the one who wrote the code) proves that a code module (the "unit") meets its requirements.  Integration Testing: A type of testing in which software and/or hardware components are combined and tested to confirm that they interact according to their requirements. Integration testing can continue progressively until the entire system has been integrated.

15 TThere are different types of maintenance. PPerfective maintenance: this implies that while the system runs satisfactorily, there is still room for improvement. AAdaptive maintenance: all systems will need to adapt to changing need within a company. CCorrective maintenance: problems frequently surface after a system has been in use for a short time, however it is thoroughly tested.

16  1. What is the System Life Cycle?  2. List and shortly describe the five main SLC stages.  3. List the contents of a feasibility report  4. List four fact finding methods  5. What is a data flow diagram?  6. Draw and describe the use of four DFD symbols.  7. Describe three alternative solutions in the design stage  8. List the details of the design specification  9. Describe the two types of documentation

17  GCSE ICT 4 th Edition   Bibliotheca

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