Detail Description of Software Design

1. E-Content
on
Software Engineering
Lesson One : Definition and Activities
Lesson Two : Software Design Principles
Lesson Three : Software Design Consideration
Lesson Four : Software Design Process
Developed by
Dr. Sandeep Kumar Nayak

2. The business process engineering hierarchy:

3. Software DesignSoftware Design:
•Software Design is a transformation of user requirement with
reference to the SRS document into design documents which
are appropriate for implementation using programming
language.

4. Software DesignSoftware Design:
•Two activities are performed in software design:
• Preliminary Design
Identification various modules
Relationship among modules
Various interface designing
Output is software architecture using notational diagram
• Detailed Design.
Data structure designing
Algorithms designing
Output is the module specification document

5. Software DesignSoftware Design:
•It is of two types:
• Function Oriented
•Problem can be viewed as a set of function.
•Most of the functions share global data.
• Object Oriented
•Problem can be viewed as a collection of objects
•Data is hidden and can not be accessed by external functions.

6. Software DesignSoftware Design:
Characteristics of good software design:
•Correctness
•Understandability
•Efficiency
•Maintainability

7. Software Design Tool:Software Design Tool: Data Flow Diagram (DFD)Data Flow Diagram (DFD) ::
•Types of DFD
• Logical DFD
• Physical DFD
•DFD Components

8. Software Design Tool: Data Flow Diagram (DFD) :
•Levels of DFD
• Level 0
Show entire system in one diagram with high level
abstraction.
• Level 1
Show the basic modules of the system with data
flow among them.
• Level 2
elaborate all the modules with data flow between,
inside the modules and data store.

9. Software Design Tool: Structure Charts
•It derived from the DFD and it more elaborative at lower level
module

10. Software Design Tool: HIPO Diagram
•It shows the modules hierarchy of system.
•It shows the flow of data and control in a module.

11. Software Design Tool: Entity-Relationship Model
•It shows the entities and their relationship.

12. •Modularization
• It follows divide and conquer rule.
• Software system divides into various independent
module.
•Advantage of modularization:
• Modules can be reused.
• Easy maintenance.
• Abstraction can be achieved easily.
• Concurrent processing of module can possible.

13. •Concurrency
• Ability to execute more than one module in parallel
to each other
• Identify modules which can be executed in parallel.
•Design Verification
• Detection of mistake and missing.
• Structured verification approach for verification

14. •Software Design Complexity
• Halstead's Complexity Measures
• Cyclomatic Complexity Measures
• Function Point

15. Object Oriented Design : Process Flow :

16. Object Oriented Design : UML diagrams :
•This diagram captures the five view of a system.
User’s View
Use case Diagram
Structural View
Class Diagram
Object Diagram
Behavioral View
Sequence Diagram
Collaboration Diagram
State Chart Diagram
Activity Diagram
Implementation View
Component Diagram
Employment View
Deployment Diagram

17. • Class Diagram
• Object Diagram

18. • Sequence
Diagram
• Collaboration
Diagram

19. • State Chart
Diagram
• Activity
Diagram

20. • Component
Diagram
• Deployment
Diagram

21. • Alternative approaches should be considered to avoid
tunnel vision.
• Design should be mapped with the requirements.
• The gap between design and problem should be
minimum.
• Uniformity should be exist in the design.
• Changes can be accommodate by the design
whenever required.

22. • To avoid inconsistency, ambiguity and omissions,
design should be reviewed.
• Quality of design should be exist and maintain after
development.
• Design is not a coding.
• For occurring any unexpected situation, design
should be structured to degrade gently

23. • Translating the analysis model into a software design

24. • Translating the Object Oriented analysis model into a
software design

25. • Abstraction:
procedural abstraction, data abstraction and Control
abstraction
• Refinement:
process of elaboration
• Modularity:
Modular decomposability, Modular composability,
Modular understandability, Modular continuity and Modular
protection

26. • Software Architecture;
Structural properties, Extra-functional properties and
Families of related systems
• Control Hierarchy:
Levels of control (depth) , overall span of control (width),
Fan-out, Fan-in, superordinate, subordinate, visibility and
connectivity
• Structural Partitioning
Horizontal partitioning and Vertical partitioning

27. • Data Structure
logical relationship among individual elements of data
• Software Procedure
Details (data organization, structure, repetitive operation,
sequence of events, and exact decision points) of processing of
procured should be defined correctly.
• Information Hiding
Non relevant information should not be accessible among the
modules

28. • functional independence
Error isolation, Scope of reuse, Understandability

29. Cohesion:
•Coincidental cohesion: performs a set of tasks that relate to
each other very loosely
•Logical cohesion: elements of the module perform similar
operations
•Temporal cohesion: all the functions must be executed in the
same time span
•Procedural cohesion: set of functions of the module are all part
of a procedure

30. Cohesion:
•Communicational cohesion: all functions of the module refer to
or update the same data structure
•Sequential cohesion: elements of a module form the parts of
sequence
•Functional cohesion: different elements of a module cooperate
to achieve a single function

31. Coupling
•Data coupling: two modules are communicated using
parameters.
•Stamp coupling: two module are communicated using
composite data items
•Control coupling: execution of second module depend on the
data of one module
•Common coupling: share global data between two modules
•Content coupling: share code between two modules

33. • Data Design
Transformation of information model into data
structures which are essential in the implementation.
• Architectural design
Describes the design patterns, relationship between
elements and the rules.
• Interface design
Defines the communication between humans and the
software.
• Component-level design
Defines the procedural description of elements of the
software architecture.

34. Data Design:
•Data Modeling,
•Data Structures,
•Databases,
•Data Warehouse

35. Architectural Design Patterns
•Data-centered architectures

36. Architectural Design Patterns
•Data-flow architectures

37. Architectural Design Patterns
•Layered architectures

38. USER INTERFACE DESIGN: Characteristics of good user interface
design
•Speed of learning
•Speed of use
•Speed of recall
•Error prevention
•Attractiveness
•Consistency
•Feedback
•Support for multiple skill levels
•Error recovery (undo facility)
•User guidance and on-line help

39. Types of User Interface Design:
It can be designed into the following three categories:
• Command language based interfaces
A command language-based interface is designed unique
names to the different commands.
• Menu-based interfaces
A menu-based interface is designed using menu selection through
pointing device with least typing effort
• Direct manipulation interfaces
Direct manipulation interface is designed in the form of visual
models.

40. User Interface Design: Evaluation

41. User Interface Design: Process
•User, task, and environment analysis and modeling
•Interface design
•Interface construction
•Interface validation

42. COMPONENT-LEVEL DESIGN : Flow Chart

43. Component-level design : Box diagram

44. Component-level design : Decision table

45. Component-level design :Resultant Decision table

46. Thank You