SOFTWARE ENGINEERING AND SOFTWARE PROJECT MANAGEMENT

SRI VASAVI COLLEGE (SFW)
Department of Computer science
II B.Sc. Computer science
Online Class
Google Meet
Software Engineering and software project management
Date:(04.08.2020 )
Day :Tuesday
Presented by
R.M.ARAVIND M.SC.M.phil.,
Assistant professor
Department of Computer Science

Design and process
• Design is a process, not a set of known
• facts
• – process of learning about a problem
• – process of describing a solution
• – at first with many gaps …
• – eventually in sufficient detail to build the
• solution

Software Design Levels
Software design yields three levels of results:
• Architectural Design
• High-level Design
• Detailed Design-

Architectural Design
• The architectural design is the highest abstract
version of the system. It identifies the
software as a system with many components
interacting with each other. At this level, the
designers get the idea of proposed solution
domain.

High-level Design
• The high-level design breaks the ‘single
entitymultiple component’ concept of
architectural design into less-abstracted view
of sub-systems and modules and depicts their
interaction with each other. High-level design
focuses on how the system along with all of its
components can be implemented in forms of
modules. It recognizes modular structure of
each sub-system and their relation and
interaction among each other

Detailed Design
• - Detailed design deals with the
implementation part of what is seen as a
system and its sub-systems in the previous
two designs. It is more detailed towards
modules and their implementations. It defines
logical structure of each module and their
interfaces to communicate with other
modules.

Modularization
• Modularization is a technique to divide a
software system into multiple discrete and
independent modules, which are expected to
be capable of carrying out task(s)
independently.
• These modules may work as basic constructs
for the entire software

Advantage of modularization:
• Smaller components are easier to maintain .
• Program can be divided based on functional
aspects
• Desired level of abstraction can be brought in the
program
• Components with high cohesion can be re-used
again
• Concurrent execution can be made possible
• Desired from security aspect

Concurrency
• Back in time, all software are meant to be
executed sequentially.
• By sequential execution, we mean that the
coded instruction will be executed one after
another implying only one portion of program
being activated at any given time.
• Say, a software has multiple modules, then
only one of all the modules can be found
active at any time of execution.

Data Objects, Attributes, and Relationships
• The data model consists of three interrelated pieces of information:
• The data object, the attributes that describe the data object, and the relationships
that connect data objects to one another.
Data objects
 A data object is a representation of almost any composite information that
must be understood by software.
 By composite information, we mean something that has a number of
different properties or attributes.
 Therefore, width (a single value) would not be a valid data object, but
dimensions (incorporating height, width, and depth) could be defined as an
object.

Attributes.
• Attributes define the properties of a data object and take on one of three
different characteristics. They can be used to
(1) name an instance of the data object,
(2) describe the instance, or
(3) make reference to another instance in another table.
• In addition, one or more of the attributes must be defined as an identifier.
• The identifier attribute becomes a "key" when we want to find an instance
of the data object.
• In some cases, values for the identifier(s) are unique, although this is not a
requirement. Referring to the data object car, a reasonable identifier might
be the ID number.

Relationships.
• Data objects are connected to one another in different ways. Consider two
data objects, book and bookstore. These objects can be represented using
the simple notation.
• A connection is established between book and bookstore because the two
objects are related. But what are the relationships?
• To determine the answer, we must understand the role of books and
bookstores within the context of the software to be built.
• We can define a set of object/relationship pairs that define the relevant
relationships. For example,
• A bookstore orders books.
• A bookstore displays books.
• A bookstore stocks books.
• A bookstore sells books.
• A bookstore returns books.

SOFTWARE ENGINEERING AND SOFTWARE PROJECT MANAGEMENT

Cardinality and Modality
Cardinality:
 The data model must be capable of representing the number of
occurrences objects in a given relationship.
 Tillmann [TIL93] defines the cardinality of an
object/relationship pair in the following manner

• One-to-one (l:l) An occurrence of [object] 'A' can relate to one and
only one occurrence of [object] 'B,' and an occurrence of 'B' can
relate to only one occurrence of 'A.'
• One-to-many (l:N) One occurrence of [object] 'A' can relate to one
or many occurrences of [object] 'B,' but an occurrence of 'B' can
relate to only one occurrence of 'A.‘ For example, a mother can have
many children, but a child can have only one mother.
• Many-to-many (M:N) An occurrence of [object] 'A' can relate to
one or more occurrences of 'B,' while an occurrence of 'B' can relate
to one or more occurrences of 'A.‘ For example, an uncle can have
many nephews, while a nephew can have many uncles.

Modality
The modality of a relationship is 0 if there is no explicit need for the
relationship to occur or the relationship is optional.
 The modality is 1 if an occurrence of the relationship is mandatory.
To illustrate, consider software that is used by a local telephone
company to process requests for field service.
 A customer indicates that there is a problem. If the problem is
diagnosed as relatively simple, a single repair action occurs.
 However, if the problem is complex, multiple repair actions may be
required.

Entity/Relationship Diagrams
• Entity-Relationship model is a type of database model based
on the notion of real world entities and relationship among
them.
• We can map real world scenario onto ER database model.
• ER Model creates a set of entities with their attributes, a set of
constraints and relation among them.

DESIGN METHODOLOGIES
• A more methodical approach to software design is proposed by structured
methods which are sets of notations and guidelines for software design.
• Two major rules of this method
• Programs were to be broken into functions and subroutines
 There was only a single entry point and a single exit point for any function
or routine.
 Structured methods often support some or all of the following models of a
system
 A data-flow model
 An Entity-relationship model
 A structural model
 An object-oriented model

SOFTWARE ENGINEERING AND SOFTWARE PROJECT MANAGEMENT

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