12 ooad uml-16

Object-Oriented Analysis and Design Using UML
Objectives

In this session, you will learn to:
Identify various dimensions of quality processes
Define extension mechanisms of UML

Ver. 1.0 Slide 1 of 23

Introducing Quality Process

The purpose of quality processes is to examine the quality
of software models and products developed during the
software development process.
Quality process includes:
Quality of the software development process that is used to
develop the software system.
Quality of the software models that are used for the software
development process.
Quality of the software product obtained at the end of the
software development process.
Quality of the quality process itself.


Identifying Dimensions of Quality Process

The dimensions that need to be considered to produce a
quality product are:
– Technology: Describes the tools required for the software
development process and the output generated.
– Methodology: Describes the sequence of actions that need to
be performed during the software development process to
generate output.
– Sociology: Describes the human resources, environmental
conditions, and skills required for the software development
process.


Identifying Dimensions of Quality Process (Contd.)

Quality checks that you need to apply to ensure the quality
of software products are:
Data quality
Code quality
Model or architecture quality
Process quality
Management quality
Quality environment


Just a minute

• Which of the following quality checks ensures that the
series of activities and tasks performed to develop software
products are correct?
1. Code quality
2. Process quality
3. Management quality
4. Model or architectural quality

Answer:
Process quality


Quality by UML

Modeling enhances the quality of software products
because it enables you to understand the existing software
system and create the desired software system.
To improve the quality of software products, you need to
analyze the effect of UML on the following quality aspects:
– Quality of visualization: Refers to the quality of visual
representation of the artifacts, diagrams, and models.
– Quality of specification: Refers to the quality of the
specifications that provide detailed description of UML artifacts
and diagrams.
– Quality of construction: Refers to the quality of the code
generated from the UML models.
– Quality of documentation: Refers to the quality of the
document that provides guidelines for creating UML artifacts
and diagrams in software models.


Quality by UML (Contd.)

To verify and validate the quality of the software models,
you need to apply quality assurance techniques.
The quality assurance techniques check the following:
– Syntax: To ensure that the software models are syntactically
correct.
– Semantics: To ensure that the software models represent their
intended meaning and their representation is consistent across
the project.
– Aesthetics: To ensure that the software models are symmetric
and complete.


Describing Quality Process Metamodels

Quality process metamodel:
Defines a language for representing another model.
Enables you to understand and describe the elements of a
quality process that are applicable to software development
process.
Depicts the rules that describe how the elements of a quality
process are connected and related to each other.


Describing Quality Process Metamodels (Contd.)

UML Notations for Elements of Quality Process:


Describing Quality Process Metamodels (Contd.)

Process-Component:
A process-component is a set of activities, tasks, roles, and
output of the quality process.
The people who perform roles of a process-components
execute activities and tasks to produce desired output.
For example: Requirement modeling, system designing, and
testing can be process-components in an UML-based project.


Just a minute

• Which of the following process-components indicates the
execution of a sequence of process-components with
varying intensity?
1. Iteration
2. Output
3. Task
4. Activity

Answer:
Iteration


Demo: Identifying Dimensions of Process-Components

Problem Statement:
The supermarket stocks a set of items. Customers take the
items from different counters in required quantities and deposit
them at the billing counter. The clerk enters the code number
of the items and their respective quantity/units. The manager of
the super market plans to automate the existing system by
implementing Supermarket Automation Software (SAS).
The SAS should provide the following features:
Print the bill containing the serial number of the sales transaction,
the name of each item, code number, quantity, unit price and the
total price at the end of a sales transaction. The bill should indicate
the total amount payable.
Print the sales statistics for items that are sold in the supermarket
for any particular period. The sales statistics should indicate the
quantity of an item sold, the price realized, and the profit.


Demo: Identifying Dimensions of Process-Components (Contd.)

Maintain the inventory of the various items of the super market.
The manager upon query should be able to see the inventory
details. In order to support inventory management, the inventory of
an item should be updated whenever an item is sold.
Enable an employee to update the inventory when a new supply
arrives.
Which of the SDLC model is best suited for developing SAS?
What are the roles, activities, tasks, and deliverables for the
design process-component of the development process?
Create a quality process metamodel for the design process
component.


Demo: Identifying Dimensions of Process-Components (Contd.)

Solution:

Microsoft Word
Document


Understanding Extension Mechanism of UML

UML provides several extension mechanisms that enable
developers to modify the software models without changing
the existing notations.
UML also provides additional modeling constructs that
represent flow of events in a software system.


Tailoring UML

UML can be tailored according to a particular application
domain.
The three types of extension elements provided by UML
are:
– Stereotypes: Extends the vocabulary of UML
– Constraints: Extends the semantics of building blocks of UML
– Tagged values: Extends the properties of building blocks of
UML
Stereotypes:
Represent model elements for which UML does not have a
specific notation.
Enable you to distinguish between representation of two similar
elements in a UML diagram.
Are represented as a text string enclosed within guillemets
(<< >>).

Tailoring UML (Contd.)

Constraints:
Represent restrictions and relationships that cannot be
represented using UML notations.
Represent global conditions or conditions that affect several
elements of UML diagrams.
Are enclosed within braces in UML diagrams.
Tagged values:
Store project management related information, such as date of
creating an element and the development and test status of the
element.
Store information about stereotyped model elements.
Can be attached to any model element.
Are represented as a pair of strings within braces.


Modeling Additional Constructs

While modeling a software system using UML, you need to
consider the concurrency and synchronization of the events.
UML provides two standard stereotypes that apply to active
classes for modeling the concurrent flow of events in a
software system:
– process: Represents that a process can execute concurrently
with other processes.
– thread: Represents that a thread can execute concurrently
with other threads within the same process.


Modeling Additional Constructs (Contd.)

Steps to model multiple flows of events in UML class and
interaction diagrams are:
1. Identify the concurrent flow of events in a software system.
2. Identify active objects based on the concurrent flow of events.
3. Group the common set of active objects into an active class.
4. Balance the distribution of responsibilities among the active
classes.
5. Ensure that each active class is both tightly cohesive and
loosely coupled.
6. Create class diagrams to represent static semantics of the
system.
7. Create interaction diagrams to represent dynamic semantics
of the system.



1. Apply the various types of communication methods among
objects.
2. Attach constraints to ensure synchronization among objects.



History state enables a sequential composite state to
remember the last sub-state that was active before the
composite state.
UML provides two types of history states:
– Shallow: Enables an application to remember and reactivate a
state that is at the same nesting depth as the history state.
– Deep: Enables an application to remember and reactivate a
state that is nested at some depth within the composite state.
System designers use comments in UML diagrams to
provide additional information to the programmers about a
model element or a group of model elements.
You depict a comment in UML diagrams by using a note
symbol.


Summary

In this session, you learned that:
The quality process is implemented between iterations and
increments of the software development process to ensure the
quality of software products.
The quality process checks the quality of output after each
phase of software development process.
The software development and quality processes are together
known as the quality software process.
The quality process consists of three dimensions:
– Technology: Describes what the software development process
produces.
– Methodology: Describes how the software development process
produces the software.
– Sociology: Describes who produces the software in the software
development process.


Summary (Contd.)

The activities of each dimension of quality process occur
simultaneously.
UML affects the quality of visualization, specification,
construction, and documentation of software models.
To ensure the quality of software models, you need to check
their syntax, semantics, and aesthetics.
The quality process metamodel depicts the elements of quality
process and their relationships.
The elements of quality process are process-components,
roles, activities, tasks, outputs, and iterations.
To modify UML, you can use the extension elements:
stereotypes, constraints, and tagged values.
UML also provides additional modeling constructs, such as
history states, notes, and comments.


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