PROGRAM DEVELOPMENT LIFE CYCLE

Programmin

gRISHI RANA

115358 D1 CSE N2

PROGRAMMING

Creating algorithms is the precursor to creating

programs;

An algorithm is the blueprint, so to speak, of a

computer program.

Recall that the general problem-solving

process has 5 phases

1.Defining the problem2.Analysing the problem3.Identifying and Evaluating Possible Solutions

4.Selection and Justification of the Optimal Solution

5.Implementation and Review

In phase 5 the organisation gets a new system

This system is made up of hardware, software, people

and procedures

The process of creating this new system is called the SDLC

SDLC means the ...

Systems Development

Life Cycle

The Systems

Development Life Cycle

is therefore something of a sub-process inside

a larger overall process

The Systems Development

Life Cycleis a model used to guide Information Technology

professionals through the management of

Information Technology projects to create a new

computer system

The Phases in theSystems Development Life

Cycle are :

1.Feasibility Study2.Analysis3.Design4.Implementation5.Testing6.Maintenance

The SDLC

"Implementation and Review" therefore, is also done in stages.

Note carefully that the SDLC may mean :

- implementing a system which uses a general purpose computer program

or- implementing a system that uses another type of off-the-shelf or pre-existing package

or it may mean

- implementing a system that requires the organisation to employ/use a programmer or a team of programmers or a software house to create a custom-written software package

If the organisation chooses to buy a pre-existing computer software package, it simply has to be purchased and installed, and the staff trained to use it.

They may also have to carry out conversion activites i.e. somehow copying the data they presently have into the new program

However, if the software to meet the organisation's needs does not presently

exist, then in the "implemtation and

review" stage of problem solving, a new software

package has to be created.

In such cases the SDLC is more than just

putting a system in place but would also

have to involve creating a new software

package.

Creating a new software package

means that the project involves more than just

systems analysts, it also needs

programmers

Systems analysts evaluate the

information technology needs of an

organisation and prescribe and design

new systems for them.

Computer programmers, on the other hand, develop

and maintain the instructions to a

computer (software) which are written in a

computer language

Computer programmers take instructions from

systems analysts as to what the computer

program is to look like and what it is to do

Working together they carry out a

particular variant of the SDLC

called the PDLC

The process of creating new

software is called the

Program Development Life

Cycle

Program Development

Life CycleThe progam development life cycle is the process of developing a software according to the desired needs of a user by following a basic set of procedures

While the SDLC is about the entire system, the

Program Development Life Cycle

is concerned principally with how a new software program

comes into being and is continually maintained over

its lifetime

Program DevelopmentLife Cycle

The progam development life cycle involves • users• systems analysts• programmers and • testers

Program DevelopmentLife Cycle

The steps in program development are :

1.Requirements Definition

2.Design3.Implementation / Coding

4.Testing5.Maintenance

Program DevelopmentLife Cycle

Program DevelopmentLife Cycle

Step 11.Requirements Definition

A requirement is a document which details the needs of a customer in a service or a product

Program DevelopmentLife Cycle

Step 11.Requirements Definition

This is a critical component in the process.Users often have a vague idea of what they want in a program. It is the analyst's job to help them to flesh out these ideas

Program DevelopmentLife Cycle

Step 11.Requirements Definition

Requirements definition is the process of eliciting and documenting what the users need in a computer program

Program DevelopmentLife Cycle

Step 11.Requirements Definition

Incomplete or inaccurate requirements result in schedule delays, wasted resources and customer dissatisfaction

Program DevelopmentLife Cycle

Step 11.Requirements Definition

At the end of the requirements definition phase the systems analyst produces a document called the system specifications

Program DevelopmentLife Cycle

Step 2 2. Design

In the design phase of the Program Development Life Cycle the systems developer/software engineer creates the algorithm.The algorithm may be expressed as pseudocode and/or flowcharts

Program DevelopmentLife Cycle

Step 2 2. Design

They may use techniquse such as •modular programming• top down design• bottom up design• structured programming

Program DevelopmentLife Cycle

Step 3 3. Implementation/Coding

Coding means translating the algorithm into computer language format. The programmers who do this are also responsible for testing their results to ensure, in particular, that it contains no syntax errors

Program DevelopmentLife Cycle

Step 4 4. Testing

The program is given to a group of specialist testers and/or a group of user representatives who run it and verify that it performs according to the specifications developed in step 1

Program DevelopmentLife Cycle

Step 5 5. Maintenance

Over the life of a program, user needs or statutory requirements will mean that the program needs to be amended sometimes. This is what maintenance is about.

Program DevelopmentLife Cycle

Documentation

Some books list documentation as a separate step in the process and some do not.This is because documentation takes place over the life of the project. As one works every step of the way everything should be documented.

The PDLC is a cyclical process

THE END