K2 Level -Unit 3 Object Oriented Analysis, Structured analysis

and structured design (SA/SD)

Subjective Question -Unit 3 Object Oriented Analysis,

Structured analysis and structured design (SA/SD)

Question:1 Describe object oriented analysis concepts.

Object-Oriented Analysis (OOA) is the first technical activity

performed as part of object-oriented software engineering. OOA
introduces new concepts to investigate a problem. It is based on a set
of basic principles, which are as follows-
Solution: 1
(With step 1. The information domain is modeled.
wise marking) 2. Behavior is represented.
3. The function is described.
4. Data, functional, and behavioral models are divided to
uncover greater detail.

Differentiate between structured analysis and object oriented

Question:2
analysis.
1. Structured Analysis :
Structured analysis is a method of development that allows
and gives permission to the analyst to understand and know
about the system and all of its activities in a logical way. It is
simply a graphic that is used to specify the presentation of
the application.
2. Object-Oriented Analysis :
Solution: 2
Object-Oriented Analysis (OOA) is a technical approach
(With step
generally used for analyzing and application designing,
wise marking)
system designing, or even business designing just by
applying object-oriented programming even with the use of
visual modeling throughout the process of development to
just simply guide the stakeholder communication and
quality of the product. it is actually a process of discovery
where a team of developers understands and models all the
requirements of the system.

Question:3 Describe a class for a system using a suitable diagram.

 A class is a blueprint or prototype that defines the variables and methods
common to all objects of a certain kind.
 In the real world, we often have many objects of the same kind.
For example, our bicycle is just one of many bicycles in the
world. Using object-oriented terminology, we say that our bicycle
object is an instance of the class of objects known as bicycles.
Solution: 3
Bicycles have some attribute (current gear, current cadence, two
(With step
wheels) and behavior (change gears, brake) in common.
wise marking)
However, each bicycle's attribute is independent of and can be
different from other bicycles.
 When building bicycles, manufacturers take advantage of the fact
that bicycles share characteristics by building many bicycles from
the same blueprint. It would be very inefficient to produce a new
blueprint for every individual bicycle they manufactured.

Table 1

Discuss the relationship between object oriented analysis and object-

Question:4
oriented design.
Relationship between OOA and OOD

 OOA involves problem definition and design focuses on solution

specification.
 OOD transforms the problem representation into a solution
representation.
 The problem and solution domain representations are different
and smaller than real-world problem.
 And the solution domain includes everything in the problem
domain, plus any additional constructs required by the solution.
 However, it is difficult to determine where OOA ends and OOD
begins, because of the blundered distinction between analysis and
design in the object paradigm.
Solution: 4
(With step
wise marking)
 OOA is concerned with devising a precise, concise, understandable,
ad correct model of real-world. Before building anything complex,
such as a house, a computer program, or hardware-software system.,
the builder must understand the requirements and the real-world
environment in which will exit.
Purpose of OOA is to model the real-world system so that it can be
understood. To do this, we must examine requirements, analyze their
implications, and restate them rigorously. We must abstract important
real-world features first and defer small details until later. The
successful analysis model states what must be done, without
restricting how it is done, and avoids implementation decisions.
Purpose of OOD
The product of OOA is used to make design further in OOD.

Discuss the various steps in Object-oriented analysis and design

Question:5
process using a suitable diagram.
Object oriented and analysis process
 OOAD begins with a problem statement (requirement) generated
by users and possibly customer.
 The requirement may be incomplete of informal, and
identification processes make it more precise and exposes
ambiguities and inconsistencies.
 The requirement should not be taken as immutable but should
serve as a basis for refining the real requirements. Next, the real-
world system described by the requirement must be understood
and identified, and its essential features abstracted into a model.
Solution: 5  Identifying objects, attributes, associations and behaviours of the
(With step object is the important step in constructing an object model.
wise marking)  And the next step is to organize classes by using inheritance to
share common structure.
 Inheritance can be added in two directions:
1. by generalizing common aspects of existing classes into a
superclass (bottom up or generalization)
2. refining existing classes into specialized subclasses (top
down or specialization).
 The object identification and refinement process are called object
model creation process.
 The last OOAD step is to implement class model using a
programming language.
 Table 2

Question:6 Describe various steps in structured analysis.

Structured Analysis is a logical tool to understand and describe the
information system in a logical way which uses graphical tools in an
organized manner that makes use of graphical diagrams to develop and
present system specifications to users in a way that makes them clear and
easy to understand.
Some of the important steps involved in structured analysis are as below:

Solution: 6  Studying the current system and evaluating all of its issues
(With step  Modelling this system
wise marking)  Modelling the new system around these issues, in order to fix
them
 Modelling the new physical environment
 Evaluating any alternatives
 Choosing the best system approach
 Creating the graphical specifications
 Question:7 Discuss various tools of structured analysis.
Tools of Structured Analysis:
Following are the various tools and techniques which are used for system
development. They are –
• ER Model
Solution: 7
• Flowchart
(With step
• Data Flow Diagrams
wise marking)
• Decision Trees
• Decision Tables
• Structured English
• Data Dictionary

Describe data dictionary as tools for structured analysis. Give a

Question:8
suitable example to illustrate data dictionary.
Data Dictionary:
Defines each term (element) encountered during the analysis and
design of a new system. It is a special kind of dictionary which contains
all the information about the data of a system. It forms an integral part
of structured specification. It is only a documentation of data.
The important components of data dictionary are:
1. Data Element: Smallest unit of data that is meaningful or pieces
of data which can’t be meaningfully decomposed are known as
data elements. For each data element the data dictionary should
Solution: 8 hold the following description:
(With step wise  Name
marking)  Description
 Name of the relative data element
 Length and type of data element
 Codification Structure
 Range of value and their meaning
2. Data Structure: They are made up data element or a combination
of both data element and data structure.
They should contain the following information:
 Name
 Description
  Included data elements and data structure with brief description
3. Data Flow: Contains the volume of flow (Start, End) point with
the description of data.
4. Data Store: Additional information on the volume and data flows
to and from it is also usually recorded.
5. Process: Documenting the processes include documenting name
and brief description of the process followed by a process
description. The entry for each and every process forms a part of
data dictionary.

Question:9 Discuss the importance of structured chart in structured analysis.

Structured Chart:
A top-down modular design tool which shows the breakdown of a system to
its lowest manageable levels with the help of graphical representation of:
Solution: 9 • Squares represent different modules in the system
(With step • lines that connect modules which shows the relationship between modules.
wise marking)
A structure chart is a tree of sub-routines in a program which indicates the
interconnections among the sub-routines. The sub-routines should be labeled
with the same name used in the pseudo code.

Question:10 Explain structured chart using a diagram.

A structure chart depicts:
• the size and complexity of the system, and
Solution: 10
• number of readily identifiable functions and modules within each function
(With step
and
wise marking)
• Whether each identifiable function is a manageable entity or should be
broken down into smaller components.
 Question:11 Explain Jackson system development approach for developing a system.
Jackson System Development (JSD)
It is a method of system development that covers the software life cycle
either directly or by providing a framework into which more specialized
techniques can fit. JSD can start from the stage in a project when there is
only a general statement of requirements. However many projects that
have used JSD actually started slightly later in the life cycle, doing the first
steps largely from existing documents rather than directly with the users.
Phases of JSD:
JSD has 3 phases:
1. Modelling Phase: In the modelling phase of JSD, the designer
creates a collection of entity structure diagrams and identifies
the entities in the system, the actions they perform, the
Solution: 11 attributes of the actions and the time order of the actions in
(With step the life of the entities.
wise marking) 2. Specification Phase: This phase focuses on actually what is
to be done? Previous phase provides the basic for this phase.
An sufficient model of a time-ordered world must itself be
time-ordered. Major goal is to map progress in the real world
on progress in the system that models it.
3. Implementation Phase: In the implementation phase JSD
determines how to obtain the required functionality.
Implementation way of the system is based on the
transformation of the specification into an efficient set of
processes. The processes involved in it should be designed in
such a manner that it would be possible to run them on
available software and hardware.

Question:12 Discuss merits of Jackson system development.

 Merits of JSD:
 It is designed to solve the real-time problems.
Solution: 12  JSD modelling focuses on time.
(With step  It considers simultaneous processing and timing.
wise marking)  Provides functionality in the real world.
 It is a better approach for microcode applications.

Question:13 Discuss demerits of Jackson system development.

Demerits of JSD:
 It is a poor methodology for high level analysis and database
design.
Solution: 13
 JSD is a complex methodology due to pseudo code
(With step
representation.
wise marking)
 It is less graphically oriented as compared to SA/SD or OMT.
 It is a bit complex and difficult to understand.

Question:14 Describe concept of object in OOPs?

A class instance is referred to as an object. A real-world object is

something like a pen, a laptop, a phone, a bed, a keyboard, a mouse,
or a chair. A physical entity is referred to as an object. In Java, there
Solution: 14 are many methods for creating objects, including the new keyword,
(With step the newInstance() method, the clone() method, the factory method,
wise marking) and deserialization.
Here is the real-life example of an object in OOPS is: Class: Human,
Object: Man, Woman
Class: Fruit, Object: Apple, Banana, Mango, Guava, etc.

Question:15 Which are the best features of OOPs, and why explain?
Encapsulation, inheritance, and polymorphism are three
fundamental elements of object-oriented programming that
distinguish it from non-OOP languages.
Encapsulation is the process of creating self-contained modules that
Solution: 15
connect processing processes to data. Classes are organized into
(With step
hierarchies, and inheritance enables one class’s structure and
wise marking)
functions to be transferred down the hierarchy. Finally, object-
oriented programming enables the creation of procedures regarding
objects whose precise type is unknown until runtime is known
as polymorphism.
 Table 3

Question:16 Differentiate procedural and object-oriented programming language.

Procedural vs OOP

procedural Oriented
Programming Object-Oriented Programming

In object-oriented
In procedural programming, programming, the program is
the program is divided into divided into small parts
small parts called functions. called objects.

Object-oriented programming
Procedural programming follows a bottom-up
follows a top-down approach. approach.

Object-oriented programming
There is no access specifier in has access specifiers like
procedural programming. private, public, protected, etc.

Adding new data and functions Adding new data and function
Solution: 16 is not easy. is easy.
(With step
wise marking)
Procedural programming does Object-oriented programming
not have any proper way of provides data hiding so it
hiding data so it is less secure. is more secure.

In procedural programming, Overloading is possible in

overloading is not possible. object-oriented programming.

In object-oriented
In procedural programming, programming, the concept of
there is no concept of data data hiding and inheritance is
hiding and inheritance. used.

In procedural programming, In object-oriented

the function is more important programming, data is more
than the data. important than function.

Procedural programming is Object-oriented programming

based on the unreal world. is based on the real world.
 Procedural programming is Object-oriented programming
used for designing medium- is used for designing large and
sized programs. complex programs.

Procedural programming uses Object-oriented programming

the concept of procedure uses the concept of data
abstraction. abstraction.

Code reusability absent in Code reusability present in

procedural programming, object-oriented programming.

Examples: C, FORTRAN, Examples: C++, Java, Python,

Pascal, Basic, etc. C#, etc.

Explain the mapping steps of object-oriented concepts using a non-object

Question:17
oriented language. Give a suitable example.
Implementing an object-oriented concept in a non-object oriented
language requires the following steps :
1. Translate classes into data structures :
i. Each class is implemented as a single contiguous block of attributes.
Each attribute contains a variable. Now an object has state and identity
and is subject to side effects.
ii. A variable that identifies an object must therefore be implemented as a
sharable reference.
2. Pass arguments to methods :
i. Every method has at least one argument. In a non-object-oriented
language, the argument must be made explicit.
ii. Methods can contain additional objects as arguments. In passing an
object as an argument to a method, a reference to the object must be
Solution: 17
passed if the value of the object can be updated within the method.
(With step
3. Allocate storage for objects :
wise marking)
i. Objects can be allocated statically, dynamically or on a stack.
ii. Most temporary and intermediate objects are implemented as stack-
based variables.
iii. Dynamically allocated objects are used when there number is not
known at compile time.
iv. A general object can be implemented as a data structure allocated on
request at run time from a heap.
4 Implement inheritance in data structures :Following ways are use
to implement data structure for inheritance in non object oriented
programming language

 Avoid it.
 Flatten the class hierarchy.
  Break out separate objects.
5 Implement method resolution : Method resolution is one. main
features of an object-oriented language that is lacking in a non object-
oriented language. Method resolution can be implemented in a following
ways

 Avoid it.
 Resolve methods at compile time.
 Resolve methods at run time.
6. Implement associations : Implementing associations in a non
oriented language can be done by :

 Mapping them into pointers.

 Implementing them directly as association container objects.
7. Deal with concurrency :

 Most languages do not explicitly support concurrency.

 Concurrency is usually needed only when more than one external
event occurs, and the behaviour of the program depends on their
timing.
8. Encapsulate internal details of classes :

 Object-oriented languages provide constructs to encapsulate

implementation.
 Some of this encapsulation is lost when object-oriented concepts
translated into a non-object-oriented language, but we can still
take advantage of the encapsulation facilities provided by
language

Question:18 Explain inline function working .

In inline functions, there is no function calls, the compiler replace every
Solution: 18
instance of their calls in the code with the body of the function saving the
(With step
overhead associated with the function call mechanism.
wise marking)
- “inline” keyword can be used to specify a function as an inline.

Question:19 Where is the memory allocated for the objects?

 Many times, you are not aware in advance how much memory
you will need to store particular information in a defined variable
Solution: 19 and the size of required memory can be determined at run time.
(With step  You can allocate memory at run time within the heap for the
wise marking) variable of a given type using a special operator in C++ which
returns the address of the space allocated. This operator is
called new operator.
  If you are not in need of dynamically allocated memory anymore,
you can usedelete operator, which de-allocates memory
previously allocated by new operator.

Question:20 Differentiate between SA/SD and OMT approach.

 In the SA/SD approach, the functional model dominates, the
dynamic model is next most important, the object model least
important.
 In contrary to this, OMT modelling regards the object model as
most important, then the dynamic model, finally the functional
model.
 The Structured Analysis/Structured Design approach organizes a
system around procedures. On the contrary, an object oriented
design technique organizes a system around real world objects, or
conceptual objects that exist in the user's view of the world. Most
changes in requirements are changes in function rather than in
objects, so change can be disastrous to procedure based design. By
contrast, changes in function are readily accommodated in an
object-oriented design by adding or changing operations, leaving
the basic object structure unchanged.
Solution: 20  An SA/SD design has a clearly defined system boundary, across
(With step which the software procedures must communicate with the real
wise marking) world.The structure of a SA/SD design is derived in part from the
system boundary, so it can be difficult to extend a SA/SD design to
a new boundary. To the contrary, it is much easier to extend an
object-oriented design.
In SA/SD the decomposition of a process into sub-processes is
somewhat arbitrary. Different people will produce different
decompositions. In the object-oriented design the decomposition is
based on objects in the problem domain, so developers of different
programs in the same domain tend to discover similar objects. This
increases reusability of components from one project to the
next.
The object-oriented approach better integrates databases with
the programming code. One common uniform paradigm, the object, can
model both database and programming structure. In contrast, a
procedural design approach is inherently awkward at dealing with
databases.

Question:21 Discuss the concept of concurrency in OO analysis.

For certain kinds of problems, an automated system may have to handle
Solution: 21
many different events simultaneously. Other problems may involve so much
(With step
computation that they exceed the capacity of any single processor. In each of
wise marking)
these cases, it is natural to consider using a distributed set of computers for
 the target implementation or to use processors capable of multitasking. A
single process - also known as a thread of control is the root from which
independent dynamic action occurs within a system. Every program has at
least one thread of control, but a system involving concurrency may have
many such threads: some that are transitory, and others that last the entire
lifetime of the system's execution. Systems executing across multiple CPUs
allow for truly concurrent threads of control, whereas systems running on a
single CPU can only achieve the illusion of concurrent threads of control,
usually by means of some time-slicing algorithm.

Question:22 Why Software Is Inherently Complex?

This external complexity usually springs from the "impedance mismatch"
that exists between the users of a system and its developers: users generally
find it very hard to give precise expression to their needs in a form that
Solution: 22 developers can understand In extreme cases, users may have only vague ideas
(With step of what they want in a software system. This is not so much the fault of either
wise marking) the users or the developers of a system; rather, it occurs because each group
generally lacks expertise in the domain of the other. Users and developers
have different perspectives on the nature of the problem and make different
assumptions regarding the nature of the solution.

Table 4

Question:23 Explain the concept of persistence in object oriented system.

An object in software takes up some amount of space and exists for a
particular amount of time. Atkinson et al. suggest that there is a continuum of
object existence, ranging from transitory objects that arise within the
evaluation of an expression, to objects in a database that outlive the execution
of a single program.
Solution: 24
This spectrum of object persistence encompasses the following:
(With step
o “Transient results in expression evaluation
wise marking)
o Local variables in procedure activations
o Own variables global variables, and heap items whose extent
is different from their scope
o Data that exists between executions of a program
o Data that exists between various versions of a program
o Data that outlives the program"

How invoking method is different in traditional and object oriented

Question:25
programming?
In traditional programming languages, invoking a subprogram is a
Solution: 25 completely static activity. In Pascal for example, for a statement that calls the
(With step subprogram P, a compiler will typically generate code that creates a new
wise marking) stack frame, places the proper arguments on the stack, and then changes the
flow of control to begin executing the code associated with P. However, in
 languages that support some form of polymorphism, such as Smalltalk, and
C++, invoking an operation may require a dynamic activity, because the class
of the object being operated upon may not be known until runtime. Matters
are even more interesting when we add inheritance to the situation. The
semantics of invoking an operation in the presence of inheritance without
polymorphism is largely the same as for a simple static subprogram call, but
in the presence of polymorphism, we must use a much more sophisticated
technique.

Table 5

Question:26 Explain the role of classes and objects in analysis and design.
classes and objects are the key abstractions of the problem, and these are
cooperative structures the mechanisms of the implementation.
During these phases of development, the focus of the developer must be upon
Solution: 26 the outside view of these key abstractions and mechanisms. This view
(With step represents the logical framework of the system, and therefore encompasses
wise marking) the class structure and object structure of the system. In the later stages of
design and then moving into implementation, the task of the developer
changes: the focus is on the inside view of these key abstractions and
mechanisms, involving their physical representation.

Question:27 Describe data abstractions in brief using example.

Data abstraction-
Creating a structure that defines a complex data type and legal
operations on it. The design makes the interface of the data and
Solution: 27
operations accessible but hides the actual implementation of them.
(With step
Example: A List class can choose to implement the container of the data
wise marking)
elements as an array or as a linked list. This container is kept hidden
from the user interface but public interface is provided to element
read/write operations.