Software engineering

1. Software Life Cycle

2. Contents
System Development Phases
Analysis
Design
Implementation
Testing
System Life Cycle

3. Software Process
• The Software Process is a
structured set of activities
required to develop a software
system consisting of
Purpose of process is to deliver
software in a timely manner and
with sufficient quality to satisfy
those who have sponsored its
creation and those who will use it.

4. Software Development Model
Also called software process model.
A Process Model describes the sequence of
phases for the entire lifetime of a Software
Development.
Therefore it is sometimes also called Software
Development Life Cycle.

5. Introduction
• Fundamental concept in Software
Engineering is the Software Life Cycle.
• What is software life cycle?
It is a process used by software industry to
design, develop and test high quality
software's.
– Just like human’s life cycle

6. Software Life Cycle
Maintenance
Analy
sis
Design
Coding
Testing

7. Human Life Cycle

8. Software Products
• Software, when made for a specific requirement is
called software product.
• Types
– Generic - developed to be sold to a range of
different customers
• Examples – PC software such as editing, graphics
programs, project management tools; CAD software
– Custom- developed for a customer according to
their specification
• Examples – embedded control systems, air traffic
control software, traffic monitoring systems.

9. Software development life cycle
Analysis
Design
Coding
Testing

10. Analysis
• The process of identifying requirements,
current problems, timelines and Resources
costs

11. Analysis
• Define the user
• Define the needs
• Define the requirements
• Define the methods

12. Analysis

13. Analysis
• User
Requirements
1. Easy to use.
2. Quality Product.
3. More Safe &
Secure product.
• Software
Requirements
1. Developing Software
2. Advance Tools &
Technique

14. Design
• The business of
finding a way to
meet the functional
requirements within
the specified
constraints using
the available
technology

15. Design
1. With described in detail, including screen
layouts, process diagrams and other
documentation.
2. The output of SRS is the input of design
phase.
• Two types of design -
 High Level Design (HLD)
Low Level Design (LLD)

16. High Level Design (HLD)
1. List of modules and a overall idea of
module.
2. Interface relationship among modules.
3. Overall architecture diagrams along with
technology details.

17. Low Level Design (LLD)
• Describes each and every module in an
elaborate manner.
• Complete input and outputs for a module.

18. Implementation
• Developers use the LLD document and
write the code in the programming language
specified.
Example:
• C,C++,Java

19. Testing
• The testing process involves development
of a test plan, executing the plan and
documenting the test results.

20. Testing
–Black box testing （黑盒测试）
–White box testing （白盒测试）

21. Maintenance
• After the software is released and the
client starts using the software,
maintenance phase is started.
• Three things happen –
Bug fixing,
Upgrade,
Enhancement

22. Maintenance
• Bug fixing
Bugs arrived due to some untested scenarios.
• Upgrade
Upgrading the application to the newer
versions of the software.
• Enhancement
Adding some new features into the existing
software.