(13636) Sda Assign 1....

SESSION:2024
22222024202
3-24
SUBJECT:COMPUTER SCIENCE
SUBMITTED BY
 NAME: ZURGHUNA GUL
 ROLL NO: 13646
 ASSIGNMENT:1
 SUBMISSION DATE: 7TH OCT
 SUBMITTED TO: SIR ISMAIL AYYAB KHAN
 COURSE:SDA
DESIGN
Design means to draw or plan something to show the look, functions and working of it.
SOFTWARE DESIGN
It is also a process to plan or convert the software requirements into a step that are needed to be
carried out to develop a software system. There are several principles that are used to organize and
arrange the structural components of Software design. Software Designs in which these principles are
applied affect the content and the working process of the software from the beginning.
FOLLOWING ARE THE PRINCIPLES OF SOFTWARE DESIGN
1. PROBLEM PARTITIONING
For small problem, we can handle the entire problem at once but for the significant problem, divide the
problems and conquer the problem it means to divide the problem into smaller pieces so that each piece
can be captured separately.
For software design, the goal is to divide the problem into manageable pieces.
BENEFITS OF PROBLEM PARTITIONING

1. Software is easy to understand
2. Software becomes simple
3. Software is easy to test
4. Software is easy to modify
5. Software is easy to maintain
6. Software is easy to expand
These pieces cannot be entirely independent of each other as they together form the system. They have to
cooperate and communicate to solve the problem. This communication adds complexity.
2. ABSTRACTION
An abstraction is a tool that enables a designer to consider a component at an abstract level without
bothering about the internal details of the implementation. Abstraction can be used for existing element as
well as the component being designed.
There are two common abstraction mechanisms
 Functional Abstraction
 Data Abstraction
i. FUNCTIONAL ABSTRACTION
 A module is specified by the method it performs.

 The details of the algorithm to accomplish the functions are not visible to the user of the function.
Functional abstraction forms the basis for Function oriented design approaches.
ii. DATA ABSTRACTION
Details of the data elements are not visible to the users of data. Data Abstraction forms the basis
for Object Oriented design approaches.
3. MODULARITY
Modularity specifies to the division of software into separate modules which are differently named and
addressed and are integrated later on in to obtain the completely functional software. It is the only
property that allows a program to be intellectually manageable. Single large programs are difficult to
understand and read due to a large number of reference variables, control paths, global variables, etc.
THE DESIRABLE PROPERTIES OF A MODULAR SYSTEM ARE:
 Each module is a well-defined system that can be used with other applications.
 Each module has single specified objectives.
 Modules can be separately compiled and saved in the library.
 Modules should be easier to use than to build.
 Modules are simpler from outside than inside.
i. MODULAR DESIGN
Modular design reduces the design complexity and results in easier and faster implementation by allowing
parallel development of various parts of a system. We discuss a different section of modular design in
detail in this section:
ii. FUNCTIONAL INDEPENDENCE:
Functional independence is achieved by developing functions that perform only one kind of task and do
not excessively interact with other modules. Independence is important because it makes implementation
more accessible and faster. The independent modules are easier to maintain, test, and reduce error
propagation and can be reused in other programs as well. Thus, functional independence is a good design
feature which ensures software quality.
IT IS MEASURED USING TWO CRITERIA:
 COHESION: It measures the relative function strength of a module.

 COUPLING: It measures the relative interdependence among modules.
iii. INFORMATION HIDING:
The fundamental of Information hiding suggests that modules can be characterized by the design
decisions that protect from the others, i.e., In other words, modules should be specified that data include
within a module is inaccessible to other modules that do not need for such information.
The use of information hiding as design criteria for modular system provides the most significant
benefits when modifications are required during testing's and later during software maintenance. This is
because as most data and procedures are hidden from other parts of the software, inadvertent errors
introduced during modifications are less likely to propagate to different locations within the software.
4. TOP-DOWN APPROACH:
This approach starts with the identification of the main components and then decomposing them
into their more detailed sub-components.
5. BOTTOM-UP APPROACH:
A bottom-up approach begins with the lower details and moves towards up the hierarchy, as
shown in fig. This approach is suitable in case of an existing system.

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SESSION:2024

 NAME: ZURGHUNA GUL

 ROLL NO: 13646

 SUBMISSION DATE: 7TH OCT

 SUBMITTED TO: SIR ISMAIL AYYAB KHAN

FOLLOWING ARE THE PRINCIPLES OF SOFTWARE DESIGN

can be captured separately.

BENEFITS OF PROBLEM PARTITIONING

well as the component being designed.

There are two common abstraction mechanisms

 A module is specified by the method it performs.

ii. DATA ABSTRACTION

for Object Oriented design approaches.

THE DESIRABLE PROPERTIES OF A MODULAR SYSTEM ARE:

detail in this section:

ii. FUNCTIONAL INDEPENDENCE:

feature which ensures software quality.

IT IS MEASURED USING TWO CRITERIA:

 COHESION: It measures the relative function strength of a module.

into their more detailed sub-components.

shown in fig. This approach is suitable in case of an existing system.

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