education about software Design and architectures

1. Samra Siddiqui

2.  What is Software
 Software Crisis
 What is System Development Life Cycle (SDLC)
 Structured Design
 Prototyping
 Agile Development

3.  4 ASSIGNMENTS
 4 QUIZZES
 SESSIONAL 1
 SESSIONAL 2
 1 Presentation

4.  Module 1: Software, Crisis and Process Models
 Software Crisis History
 System Development Life Cycle and its Models
 Module 2: Agile Development
 Agile Development Practices and Models

5.  Module 3: Design and Architecture
 Design Principles
 Design Criteria
 DesignTechniques
 Module 4: Design Patterns
 Creational Design Patterns Singleton
 Creational Design Patterns Prototype
 Creational Design Patterns Builder

6.  Software is Computer Programs, Procedures,
and possibly associated Documentation and
data pertaining to the operation of a
computer System.
 All four components are needed to assure
Quality of Software.

7.  Term by F. L. Bauer at the first NATO Software Engineering
Conference in 1968 at Garmisch, Germany
 It refers to the difficulty of writing correct, understandable,
and verifiable computer programs in required time
 Exceeding of the date, budget excess, failure of the project
 Major causes of software crisis are the problems such as
malfunctioning of software systems, inefficient development of
software, and the most important, dissatisfaction amongst the
users of the software.

8.  Advances in hardware capability have enabled increasingly
complex software.
 Our ability to intellectually manage this complexity has
always lagged the advances in software complexity.
 We continually require better tools (CASE etc)

9.  46 % date or budget excess
 28 % failure
 Only 9 % of all large IT projects in time and budget

10.  Unclear, unstable, misunderstood and missing requirements
 To late integration of results of working and components,
thus to late recognition of risks and errors
 Fast changing technologies
 Missing Quality Management
 Overvaluation of documents
 No model-based process

11.  Mariner 1 was the first spacecraft of the
American Mariner Program
 It cost $18.5 million in 1962.
 A bug in the flight software for the Mariner
1 causes the rocket to divert from its intended path
on launch.
 Mission control destroys the rocket over the
Atlantic Ocean.
 The investigation into the accident discovers that a
formula written on paper in pencil was improperly
transcribed into computer code, causing the
computer to miscalculate the rocket's trajectory.

12. • On June 4, 1996 an unmanned
Ariane 5 rocket launched by the
European Space Agency exploded
just forty seconds after its lift-off
from Kourou, French Guiana.
• Crashed after 36.7 seconds.
• Caused by an overflow
error. Trying to store a 64-bit
number into a 16-bit space.

13. • Considered the largest ambulance
service in the world.
• Overloaded problem.
• It was unable to keep track of the
ambulances and their statuses.
Sending multiple units to some
locations and no units to other
locations.
• Generates many exceptions
messages.
• 46 deaths.

14.  Software Development Life Cycle is a well-defined, structured
sequence of stages in software engineering to develop the
intended software.
 A standard process followed in an organization to conduct all the
steps necessary for:
▪ Planning:Why
▪ Analysis: who, what, where and when
▪ Design: How
▪ Implementation
of an information system

15. Three types.
 Structured Design
 RapidApplication Development
 Agile Development

16.  Became dominant in 1980s replacing the
previous undisciplined approach.
 Step by step approach to the SDLC that
moves logically from one phase to the next.
 Waterfall Development

17.  ByWinston Royce -1970
 Simplest model of software development.
 Originate from Manufacturing and Construction
Industry where requirements are stable
 Due to lack of any standard software process
this model was adopted as standard for software
development.
 Change is a costly issue

18.  All the phases of SDLC
will function one after
another in linear
manner.
 That is, when the first
phase is finished then
only the second phase
will start and so on.

19.  Easy to understand, easy to use
 Provides structure to inexperienced staff
 Milestones are well understood
 Sets requirements stability
 Good for management control (plan, staff, track)
 Works well when quality is more important than
cost or schedule

20.  All requirements must be known upfront
 Deliverables created for each phase are considered
frozen – inhibits flexibility
 Can give a false impression of progress
 Does not reflect problem-solving nature of software
development – iterations of phases
 Integration is one big bang at the end
 Little opportunity for customer to preview the system
(until it may be too late)