Topic 2.1.5 SDLC Phases or Steps, Chapter 2 - System Development Life Cycle, HSSC-II (12th Class) Computer Science Key Point Notes

12th Class (HSSC-II) Computer SLO Based Key Point Notes

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Unit 2: System Development Life Cycle

Topic 2.1.6: SDLC Phases or Steps:

SDLC Phases or Steps:

1. Defining problem
2. Planning
3. Feasibility Study
4. Analysis
5. Requirement Engineering
6. Design
7. Coding
8. Testing / Verification
9. Deployment / Implementation
10. Maintenance / support

1- Defining Phase:

• In this phase, the problem to be solved or the system to be developed is clearly defined.
• The requirements are documented and approved by the customer or company.
• It is very important to identify all requirements in order to develop the project successfully.
• Example: A student Examination System needs to be developed to cover all aspects from conducting the examination and generating results.

Planning Phase:

During the planning phase:

• The objective of the project is determined
• The requirements to produce the project are considered.
• An estimate of resources, such as personnel and costs, is prepared.
• All the information is analyzed to get alternative solutions, if any.
• The information is assembled into a project plan and presented to management for approval.

Feasibility study:

• It is the analysis and evaluation of a proposed project, to determine, whether it is technically, financially, legally, and operationally feasible within the estimated cost and time.
• It is used to assess the strengths and weaknesses of the proposed project.

It is divided into the following types or forms:

Technical Feasibility: (Determines the level of and type of technology needed for the system)

Analysis Phase:

• During this phase, the project team determines the end-user requirements and provide their expectation from the new system.
• The In-charge of the project team must decide whether the project should go ahead with available resources or not.
• It is also looking at the existing system to see what and how it is doing its job.

During this phase, the project team asks the following questions:

• Can the proposed project be developed with the available resources and budget?
• Will this system improve the performance of an organization?
• Does the existing system need to be replaced?

Example: The Student Examination System is analyzed for development. The team may visit the educational institute to study the existing system to suggest improvements.

Requirement Engineering

• It is the process of determining user expectations for a new or modified system/software.
• It is a set of activities used to identify and communicate the purpose of a software/system.

It consists of the following steps:

1. Requirement gathering:

It is the first part of any system development process in which meetings with customers are arranged, and their requirements and demands are analyzed which are of two types:

• Functional Requirements which specify the software functionality that the developer must build into the system to enable users to accomplish their tasks.
• Non-Functional Requirements specify the criteria for the judgment of the operation of a system which describes how the system performs its duties.

2. Requirement Validation:

It is concerned with examining the gathered requirements to certify that they meet the intentions of the stakeholders.

3. Requirement Management:

• It is performed to ensure that the software continues to meet the expectations of the users.
• It needs to gather new requirements that arise from changing expectations, new regulations, or other sources of change.

Functional Requirements vs Non-Functional Requirements

Design Phase:

• It is the architectural phase of system development in which the project team develops a logical design for data storage and processing.
• The project team designs a mock-up or dummy user interface, for which the developers write the actual code to make it functional.

The design phase consists of two different structures:

1. Algorithm:

It is a step-by-step procedure which is used to solve a problem.

2. Flowchart:

The diagrammatic representation of an algorithm is called a flowchart.

Flow chart Symbols

Example:
The algorithm that inputs marks and prints the message “PASS” or “FAIL”. Passing marks are 33.

STEP 1: START
STEP 2: Input marks (M)
STEP 3: Comparing the marks (M) with 33 i.e.
            IF M >= 33 THEN PRINT “PASS” OTHERWISE PRINT “FAIL”
STEP 4: STOP.

Flow Chart

Coding / Construction:

• During this phase, the developers/programmers create the database, write the code in a programming language for data processing, and design the actual user interface.
• Test data is prepared and processed as many times as necessary to refine the code.
• Coding is also called computer programming.

Example:

            #include <iostream.h>
            void main(void)
            {
                        int marks;
                        cout<<”Enter Marks;
                        cin<<marks;
                        if(marks >= 33)
                                    cout<<”PASS”;
                        else
                                    cout<<”FAIL”;
            }

Testing/Verification

• The process of executing programming modules to find errors is called testing.
• During this phase, the system is tested for functionality and performance.
• The purpose of testing is to evaluate an attribute or capability of a program or system and determine whether it meets its required results.
• Testing/verification the software is actually operating the software under controlled conditions and checking and evaluating the result against pre-specified requirements.

Deployment / Implementation

It is a set of activities that are used to make the software/system available for use.

Activities involved in this phase are:

i.     Installation and activation of the hardware and software.

ii.    Train the users on the developed system.
iii.   Conversion from the old system to the new system.

Deployment Methods:

1. Direct Implementation / Deployment:

• It involves the old system being completely dropped and the new system being completely implemented at the
same time.

2. Parallel:

• This method involves operating both systems together for a period.
• This method allows any major problems with a new system to be encountered and corrected without loss of any information.

3. Phased:

• This method involves the new system being gradually introduced and the old system being progressively discarded.

4. Pilot:

• In this method, the new system is installed for a small number of users to learn, use, and evaluate.
• Once the system is performed satisfactorily, the new system is installed and used by all.

Maintenance / Support

• Maintenance can be either repairing or modification or some enhancement in the existing system.
• The performance of a system is monitored continuously and when problems or modifications are identified, the system may reenter the planning phase which will continue until a complete solution is provided to the customer.

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Topic 2.1.1: A System:

Topic 2.1.2: System Development Life Cycle (SDLC) and its important

Topic 2.1.3: Objectives of SDLC:

Topic 2.1.4: Stakeholders of SDLC:

Topic 2.1.5: SDLC Phases or Steps:

Topic 2.1.6: Personnel Involved in SDLC and their Role:

Full Chapter Key Point Notes (Topic wise)

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