CSEM01 SE Evolution

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CSEM01 SE Evolution ManagementAnne
ComerHelen Edwards
Introduction
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Introduction

• Module housekeeping (i.e. details)
• Module web page
• Staff
• Teaching learning
• Assessment
• Why this module?

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Introduction

• Module web page Go there for
• module handbook
• Lecture PowerPoint's
• Downloads
• Assignments
• Updates/News

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Introduction

• Teaching Team Members
• Anne Comer,
• anne.comer_at_sunderland.ac.uk
• Prof. Helen Edwards,
• helen.edwards_at_sunderland.ac.uk
• The majority of lectures will be given by Anne
  Comer. Both Anne Comer and Prof. Edwards will be
  on-hand during the tutorials.
• See module handbook for further details

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Introduction

• Teaching and Learning
• Lectures 18 hours, Tutorials 24 hours
• Assignment 40 hours, Self study 70 hours
• Students will be required to adopt an
  experiential and reflective learning approach, to
  critique software engineering approaches -
  evaluating the strength of evidence supporting
  claims made by proponents of the approaches and
  reflecting these against their experiences in
  their project.

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Introduction

• Assessment -
• Purely coursework, two parts (60, 40),
• 60 - project work in a small team, and
  personal project management
• 40 - one critical review (including
  presentation)

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Why this module?

• Software costs more to maintain than it does to
  develop. For systems with a long life,
  maintenance costs may be several times
  development costs
• Software engineering is concerned with
  cost-effective software development sound
  project management is essential
• The evolution of software displays a number of
  general principles across many different projects
  those principles need to be studied.

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Why this module? again.
the complexity of practice has always dwarfed
the simplicity of theory - Robert Britcher,
Limits of Software, 1999, A-Wesley. The FAA
terminated its Advanced Automation System after
expenditure of approximately 2 billion, based on
the judgement that it could not be
accomplished. On the maiden flight of the Ariane
5 it crashed about after 40 secs. The amount lost
was 500 million (1996). It was a reuse error
a module was reused from Ariane 4 (10yr-old
software). There was a complete absence of any
kind of precise specification associated with a
reusable module.
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Objectives

• To introduce software engineering and to explain
  its importance
• To set out the answers to key questions about
  software engineering, particularly with respect
  to software evolution and s.e. management.

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Software engineering

• More and more systems are software controlled
• Software engineering is concerned with theory
  and practice, paradigms of development (methods,
  tools and procedures), and empirical assessment
  and validation, - for professional software
  development.

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Software costs

• Software costs more to maintain than it does to
  develop. For systems with a long life,
  maintenance costs may be several times
  development costs
• Software engineering is concerned with
  cost-effective software development

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What is software?

• Computer programs and associated documentation
• Software products may be developed for a
  particular customer or may be developed for a
  general market
• Software products may be
• Generic - developed to be sold to a range of
  different customers
• Bespoke (custom) - developed for a single
  customer according to their specification

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What is software engineering?

• Software engineering is an engineering discipline
  which is concerned with all aspects of software
  production
• Software engineering is concerned with the
  practicalities of developing and delivering
  useful software
• Software engineers should adopt a systematic and
  organised approach to their work and use
  appropriate tools and techniques depending on the
  problem to be solved, the development constraints
  and the resources available

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What is a software process?

• A set of activities whose goal is the development
  or evolution of software
• Generic activities in all software processes are
• Specification - what the system should do and its
  development constraints
• Development - production of the software system
• Validation - checking that the software is what
  the customer wants
• Evolution - changing the software in response to
  changing demands

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What is a software process model?

• A simplified representation of a software
  process, presented from a specific perspective
• Examples of process perspectives are
• Workflow perspective - sequence of activities
• Data-flow perspective - information flow
• Role/action perspective - who does what
• Generic process models
• Waterfall
• Evolutionary development
• Formal transformation
• Integration from reusable components

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What are the costs of software engineering?

• Roughly 60 of costs are development costs, 40
  are testing costs. For custom software, evolution
  costs often exceed development costs
• Costs vary depending on the type of system being
  developed and the requirements of system
  attributes such as performance and system
  reliability
• Distribution of costs depends on the development
  model that is used

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What are software engineering methods?

• Structured approaches to software development
  which include system models, notations, rules,
  design advice and process guidance
• Model descriptions - Descriptions of graphical
  models which should be produced
• Rules - Constraints applied to system models
• Recommendations - Advice on good design practice
• Process guidance - What activities to follow

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What are the attributes of good software?

• The software should deliver the required
  functionality and performance to the user and
  should be maintainable, dependable and usable
• Maintainability - software must evolve to meet
  changing needs
• Dependability - software must be trustworthy
• Efficiency - software should not make wasteful
  use of system resources
• Usability - software must be usable by the users
  for which it was designed

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What are the key challenges facing software
engineering?

• Coping with legacy systems, coping with
  increasing diversity and coping with demands for
  reduced delivery times and higher quality.
• Legacy systems - old, valuable systems must be
  maintained and updated
• Diversity - systems are often distributed and
  include a mix of hardware and software components
• Delivery - there is increasing pressure for
  faster delivery of software
• Quality stricter adherence to both explicit and
  implicit requirements coupled with rigorous
  process visibility and process improvement

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Key points

• Software engineering is an engineering discipline
  which is concerned with all aspects of software
  production.
• Software products consist of developed programs
  and associated documentation. Essential product
  attributes are maintainability, dependability,
  efficiency and usability.
• The software process consists of activities which
  are involved in developing software products.
  Basic activities are software specification,
  development, validation and evolution.
• Methods are organised ways of producing software.
  They include suggestions for the process to be
  followed, the notations to be used, rules
  governing the system descriptions which are
  produced and design guidelines.