Software Engineering MODULE 1 - PART 1.pdf

SOFTWARE
ENGINEERING
Module 1 - Part 1
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TABLE OF
CONTENT
S
● Software and Software Engineering
● Software Process- Generic process model
● Process Improvement

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Software can be described as a collection of instruction that are executed to get desired functionalities.
Software → programs + documentation + operating procedures
Characteristics of software
● Software is developed,not manufactured
● Does not wear out
● Has reusable components
● Flexible
Software

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Types of software
● System software - software that provides a
platform to other software such as Microsoft
Windows, GNU/Linux, macOS.
● Application software - programs designed
for end users like Notepad, Firefox, Media
players.
● Engineering/Scientific software - software
built with techniques and formulae specific
to specific scientific or engineering field,
examples are MATLAB, AUTOCAD.
● Embedded software - programs that control
machines or devices such as Traffic light
control mechanism, Motorcycle dashboard
display.
Software
● Product-line software - a group of products
sharing common features that are used to satisfy
specific needs of a mission like MS Office
supporting home use, business use, enterprise
use etc.
● Web application software - programs that are run
on web servers and are accessed through a web
browser, examples are Gmail, Facebook etc.
● Artificial Intelligence software - software that is
capable of intelligent behaviour, like in Robotics,
Game Playing etc.
● Legacy software system - software systems that
were developed decades ago which becomes
costly and risky to maintain and evolve.

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Software engineering can be deﬁned as systematic and disciplined engineering approach applied for building and
maintaining software.
Software Engineering
It is a layered technology comprising
● Quality focus as its central support element since improving quality
of process and products through quality improvement techniques is
the main focus of an organization.
● Process layer provides framework for management of software
project.
● Method layer includes methods such as communication, design,
coding and other technical aspects for development of software.
● Tools layer provides supporting tools for Method and Process layers.

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Essence of Practice
General steps in carrying out software engineering are,
● Understand the problem through communication.
● Plan a solution by modelling and designing.
● Carry out the plan (coding).
● Examine result for correctness (testing).
Principle of best Practice
● Software should provide value to users.
● Keep the software design simple.
● Vision of the project should be kept in mind throughout.
● Keep your work products in an understandable format for others to work with them easily.
● Design in a way that can incorporate changes in future.
● Build reusable components.
● Think before acting or learn before starting.
Software Engineering Practice

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Management Myths
● Software practitioners follow the book of standards and procedures for software development.
● If a delay occurs, programmers can be added at any point.
● Outsourcing helps.
Customer Myths
● General requirements and not a detailed one is needed for starting programming.
● Software is easy to change.
Developer’s Myths (Practitioner’s Myths)
● Software developing is all about coding.
● Only a ﬁnished software can be tested.
● Software engineering has plentiful documentation and will slow down the process.
Software Myths (False Belief)

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Software process comprises activities performed to create
a software product.
It deals with technical and management aspects of
software development.
Software process includes
● Tasks– focus on small, specific objective.
● Action– set of tasks that produce major work
product.
● Activities– group of related tasks and actions for a
major objective.
A process framework for software engineering defines five
framework activities. In addition a set of umbrella activities
are applied throughout the process.
Software Process

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Software Process
Process Framework Activities
● Communication - Communicate with stakeholders and customers to obtain objectives of the system and
requirements for the software.
● Planning - Software project plan has details of resources needed, tasks and risk factors likely to occur,
schedule.
● Modeling - Architectural models and design to better understand the problem and for working towards the
best solution.
● Construction - Generation of code and testing of the system to rectify errors and ensuring all speciﬁed
requirements are met.
● Deployment - Entire software product or partially completed product is delivered to customer for
evaluation and feedback.

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Software Process
Umbrella Activities
Activities that occur throughout a software process for better management and tracking of the project.
● Software project tracking and control - Compare progress of the project with the plan and take steps to
maintain planned schedule.
● Risk management - Evaluate risks that can affect the outcome and quality of the software product.
● Software quality assurance (SQA) - Conduct activities to ensure quality of the product.
● Technical reviews - Assessment of errors and correction done at each stage of activity.
● Measurement - All the measurements of project and product features.
● Software conﬁguration management (SCM) - Controlling and tracking changes in the software.
● Reusability management - Back up work products for reuse and apply mechanism to achieve reusable
software components.
● Work product preparation and production - Project planning and other activities used to create work
product is documented.

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Software Process
Process ﬂow
Process ﬂow determines how activities, actions and tasks are arranged with respect to sequence and time.
→ Linear Process Flow - Executes each activity in sequence.
→ Iterative Process Flow - Repeats one or more activities before starting next.

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Software Process
→ Evolutionary process ﬂow
Carry out activities in a circular way.
→ Parallel process ﬂow
Execute one or more activities in parallel with each other.

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Software Process
Defining a Framework Activities
Consider communication activity.
For small project, this can be defined as having tasks set:
● Making phone call with stakeholder
● Discuss requirements and note it down
● Organize requirements
● Mail stakeholder for review and approval
For large projects - extended actions such as feasibility
study, elicitation of requirements, elaboration of
requirements, specification documents, validation etc.
Identifying a task set
Task set is the actual work to be done to achieve
an objective of engineering action.
For small project, consider elicitation action in
communication activity, this may include:
● Prepare list of stakeholders of the project
● Organize a meeting for stakeholders
● Discuss requirements
● Finalize requirements list
● Make a list of issues raised
For large projects - steps may be added such as
interviewing each stakeholder separately before
group meeting, more techniques are applied in
discussing requirement, etc.

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Software Process
Process patterns
Patterns used to describe problems and their solutions in the context of software process.
Problems can arise at different levels such as:
● Problems associated with a complete process model
● Within a framework activity
● Within an action in an activity
Patterns can be described using a pattern template which include
● Pattern name
● Intent
● Forces and Types
○ Stage pattern
○ Task pattern
○ Phase pattern
● Initial context
● Problem
● Solution
● Resulting context
● Related patterns
● Known uses or examples

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Software Process
An example
● Pattern name – requirements unclear.
● Intent – an approach to build a prototype so that stakeholder can assess and determine specific
requirements.
● Type – phase pattern.
● Initial context – stakeholders have been identified, communication mode has been selected, initial
understanding of problem and scope of project determined.
● Problem – recognized that stakeholder has a general idea of requirements and cannot place specific
requirements.
● Solution – prototyping can help the stakeholder to be more specific about requirements and hence
prototype can be evolved.
● Resulting context – a prototype fulfilling basic requirements is approved by stakeholder and the prototype
may be evolved or thrown for making a new one which will become the finished product.
● Related patterns – customer communication , iterative design , requirement extraction.
● Known uses/examples – unclear requirements problem can be solved through prototyping.

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Process Improvement
● Software process assessment - ensure their ability to control cost, time and quality of a software.
● Assessment is done to improve the software process.
Software Process Improvement (SPI) Cycle includes,
● Process measurement.
● Process analysis.
● Process change.
Different approaches towards process assessment include,
● CMM (Capability Maturity Model) and CMMI (Capability Maturity Model Integration).
● Standard CMMI Appraisal Method for Process Improvement ( SCAMPI).
● CMM Based Appraisal for Internal Process Improvement (CBA IPI).
● SPICE(ISO/ IEC15504).
● ISO 9001:2000 for software.

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Process Improvement
CMM (Capability Maturity Model) and CMMI (Capability Maturity Model Integration)
An approach based on which a process maturity is determined.
CMM maturity levels
1. Initial Level.
2. Repeatable Level.
3. Deﬁned Level.
4. Managed Level.
5. Optimizing Level.
CMMI maturity levels
1. Initial.
2. Managed.
3. Deﬁned.
4. Quantitatively Managed.
5. Optimized.

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Process Improvement
Standard CMMI Appraisal Method for Process Improvement ( SCAMPI)
Method used for providing quality ratings with respect to CMMI.
Assessment Phases
1. Initiating.
2. Diagnosing.
3. Establishing.
4. Acting.
5. Learning.
CMM Based Appraisal for Internal Process Improvement (CBA IPI)
It is an SEI CMM(Capability Maturity Model) based assessment method that provides diagnostics, enables and
encourages an organization to understand its maturity.
Appraisal Process
● Preparation.
● On-site activities.
● Findings.
● Ratings
● Final reporting, etc.

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Process Improvement
SPICE(ISO/ IEC15504)
Assist organizations in developing an objective
evaluation of the effectiveness of a software
process.
Levels
1. Not performed.
2. Performed informally.
3. Planned and tracked.
4. Well deﬁned.
5. Quantitatively controlled.
6. Continuously improved.
ISO 9001:2000 for software
They evaluate the ability of an organization to
consistently provide products that meet customer
requirements.
Follows PDCA cycle
1. Planning.
2. Doing.
3. Checking.
4. Acting.

Software Engineering MODULE 1 - PART 1.pdf

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