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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