Computer Science SLO Based Key Point Notes

👉👉👉 Computer Science 12th Class Notes (Main Page)

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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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👉👉👉 Computer Science 12th Class Notes (Main Page)

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(National Book Foundation - As Federal Textbook Board, Islamabad 
Based on National Curriculum Pakistan 2026-2027 and Onward prescribed by Federal Board of Intermediate and Secondary Education, Islamabad, and All Pakistan Boards) 

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