Chapter 7 - System Life Cycle

Chapter 7

System Life Cycle​

ICT LESSON

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Do you know or ever heard of system analyst?

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Do you know or ever heard of system analyst?

When an organization or a client considers that one of its systems has problems or is in need of improvement, a system analyst studies the system to determine where the problems are and how the system can be improved.

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The analyst then plans how the system is going to be imported into the organization and arranges for continuing maintenance of the system. This whole process is known as the systems life cycle and can be summarized as:

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Analysis

Development and testing

Documentation

Design

Implementation

Evaluation/Maintenance

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The main stages of a system life cycle are .....

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The system life cycle or the system development life cycle (SDLC) is often depicted using a diagram known as the waterfall model.

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​ Analysis : Collecting information about the present system and identifying problems.

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Design : Designing a new system to correct the problems identified in the analysis.

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Implementation: Replacing the old system with the new system.

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Testing : testing new system

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Deployment: released the new system

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Maintainance: There are some issues which come up in the client environment and also to enhance the product some better versions are released.

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​Iteration

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This stage starts with the definition of the problem and a suitable study.

Analysis

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Process:​ Collecting information by observing the user or client's work environment.

Observations

​Advantages

• No detailed planning is required.​

• Less time-consuming

• Helps the analysts understand the requirements in real-time

• Effective method.​

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what disadvantages of observation?

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Process:​ People who use the system are interviewed to collect their feedback.

Interview

​Advantages

• The analyst can open ended questions to collect more feedback and questions can be modified during interview.

​Disadvantages

• It can be a time-consuming process and interviewees cannot remain anonymous with this method.

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Process:​ Questionnaires are distributed to employees/customers to find out a range of opinions about the current system.

Questionnaire

​Disadvantages

• May not be completely accurate, not all returned and vague answers

​Advantages

• Can reach a larger audience and save more times.

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Process:​ Existing documentation for the current system is analyzed to identify what data is inputted and outputted.

Collecting Documentsr

​Advantages

• Analysts can see how current system operates and obtain information which is critical to the system

​Disadvantages

• It can be a very time-consuming process.

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With one of those techniques mentioned before a list will be formed of what will be necessary for the solution. This list of the requirements specification

Open Ended

An entrepreneur builds a food company, and for a week, he doesn't get enough customers. he has tried to promote his business using flyers, what should be done to make his business grow?

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Based on the information from the analysis stage, a new system will be designed. The new system will hope to resolve the issues identified in the current system.

design

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Based on the information from the analysis stage, a new system will be designed. The new system will hope to resolve the issues identified in the current system.

design

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When designing a new system you need to think about what the outcome will look like

design

The important part is to decide what the organization/client wants to happen in the end. If they like the output, they are likely to accept the whole solution.

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The basic four symbols of a dfd

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​Function

​File or database

​Information flow

​Input or output

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definition of a Data flow diagram (dfd)

​Data flow diagrams are used to visualise the information that enters, leaves, or effects a system within a system

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Uses of a data flow diagram​

1. ​To find the inputs, outputs, processes, and storage information for the proposed system.

2. ​To identify the pros and cons of any changes planned for the new system.

3. To identify system requirements such as hardware and software for the planned systems​

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Design phase

The design phase of the system life cycle is important as it helps show how the new system will look.​

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input Design

The analyst has to decide how the data will be collected and design a method of inputting it. For example:

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•Is the input manually or automatically? manual data collection means the users have to insert the data by themselves, while automatic data collection can use sensors as the input.

•Are the data captured forms using paper-based or electronic-based? This depends on the application

•Is the data going to be input by someone using a keyboard? Screen? or papers?​

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input Design

A system analyst has been asked to create an ICT system for their bookshop. What do you think needs to be inserted into the system?​

​Before a data input form can be created the database has to be created. The following need to be considered:

•Type of data that will capture and input.

•Different tables which may be required and relationships which could be established.

•Different fields (including Key) would be required.

•Data types that would be required for each field

•Text

•Integer (numeric)

•Double

•Boolean (Yes/No)

•OLE Object (Image)​

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input Design

​Paper Based Forms Must Include:

•Clear heading and instructions.

•Use of text boxes to collect information such as name,  DOB, etc.

•Use of tick boxes to make choices easier (Gender).

•Clear fonts and text styles.

​Electronic Forms Include:

• Text boxes

• checkboxes

• Buttons

• radio buttons/options buttons

• list boxes

• drop-down menus​

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documentation​

​To any organization, documentation is the most reliable form of information as the users can always refer back to the documents. A new system is always supported by two types of documents:

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Technical documentation

​Technical documentation is the information about the solution that a technician needs in order to understand how the system works.

​This explains how the system was developed and includes information such as hardware and software requirements, file structures, and coding used.

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Technical documentation

​Technical documentation is required when updating or fixing problems with the system. It will include:

​This is the definition of the problem that the system solves, as agreed with the client.

​If the purpose of the system meets the requirement then we can move on to the next technical documentation.

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Technical documentation

​There will be some limitations put on the system in the initial discussions between the client and the analyst.

​The limitation may vary, some examples are the client wants to add a new feature of the system, but the analyst thinks it will add too much cost and time.

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Technical documentation

​These will show the complete information system in a graphical or visual concept. Sometimes referred to as the system architecture

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​Details of any programming done will need to be included, such as the original designs for the program, possibly in the form of program flowcharts as well. The program itself must be fully annotated.

​Annotation is a term used in computer programming to refer to documentation and comments that may be found in code logic.

​Because sometimes programmer will require an explanation of the rationale behind the logic, an explanation of how the logic accomplishes its purpose or simply leaving a mark to their code.

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​This will include the name of the variable, the reason it is being used ,and the data type.

​This is to help technicians follow the program if some maintenance needs to be done and to ensure that variables are not duplicated.

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​The hardware needed to run the system is also listed, including estimated file sizes.

​software requirements should also be listed, including details of the software that has been bought, used, or modified during the process.

​Minimum system requirements for running the software will also be included.

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​This defines the data types of all the fields in the files used by the system.

​It also shows the linkages between the files. If the system uses databases, then the database management system will have a view that shows the relationship between the tables.

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​When a system is already implemented, validation of each module is also routinely checked, to ensure all data given are correct and there is no problem during the process of each module.

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​User documentation is provided for the people who will use the system. Users do not need to know how the system works in detail, however, there are some features and functions that they should know:

​User documentation

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​This will include:

•The sort of data that needs to be input

•How to input the data

•How to format it

​It is basically like creating a manual for the users to learn how to use the system.

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​The outputs from some successful runs of the software should be shown so that the user has a reference of how the system should look if it is used properly.

​This could be in the form of a video tutorial.

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​Things can go wrong, especially a new system is implemented and users with their first experience with it. It is important to have a message showing what is wrong when users inputted the wrong data into the system, so the users can repeat the process and enter the correct data.

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​There should be some assistance given for minor problems that can arise with the system being used.

​The trouble-shooting guide tells the user how to identify that certain things have gone wrong and what can be done about them.

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​Experiences are the best teacher. Problems that occur within the process are collected together with the answers that go with them.

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​1. Name the stages of the system's life cycle.

​2. Name 3 ways you could research an existing system.

3. Describe these methods of researching an existing system.

• Observation

• ​Interviews

• Questionnaires

​Assignment