System Development Process

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System Development Process
Lecture 9 BSIT-2nd (ME)
Inam Ul-Haq Assistant Professor (IT) University
of Okara Inam.bth_at_gmail.com
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Outline

• System Development Process
• Two Forms of System Development Process
  (Waterfall Iterative)
• System Planning for Process Optimization
• System Analysis Design
• Good System Design
• System Construction, Installation, Testing
• System Deployment Maintenance

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System Development Process

• __________________Focus on___________
• ? Organizational goals plans
• Org. processes and data As-is vs. To-be
• System solutions to problems in org. processes
  data
• Result of IS Analysis Design are system
  requirements
• Programming, purchasing software hardware also
  called implementation
• Reality check
• Fine-tuning the system

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System Development Model1- Waterfall Model

• System development steps can be run on the entire
  system sequentially in defined periods. This is
  Waterfall methodology.
• Linear, no turning back to previous step.
• Inflexible once defined system requirements are
  fixed.
• If development time longer, system may be
  obsolete at time of release.

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2- Iterative Model
System Part ...
System Part A
System Part B
System Part C
.
More parts? N
All
Y
.
One run of Plan-to-Test is called iteration.
Some system parts can take more than 1 iteration.
Even previously developed and tested parts could
be revised later in the iterative developing
process.
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Iterative Methodology

• An alternative to sequential development of
  systems
• Methodology
• Break whole system into smaller pieces that
  functionally build on each other.
• For example Focus on one system function.
  Develop software for it as well as a part of
  database and part of user interface for it.
• Analyze, design and construct a piece quickly
  test it on users, revise, and move on to next
  function.

Strengths Weaknesses
Rapid, savings (people, time, ) Less suitable for large, complex systems due to system integration issues
Useful when system requirements are less certain due to dynamic business May neglect details in analysis, documentation and testing
Involves users in process, not at the end only May neglect details in analysis, documentation and testing
Information Systems for Management
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Information Systems for Management
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Perform System Analysis

• The goal is to understand the existing (present)
  business and systems (As-is) in order to create
  improvements (To-be).
• Focus on the present
• Analysis of present organizational processes
  (design, performance) - interview end-users
  managers.
• Analysis of present data as part of
  organizational processes - collect business
  documents, analyze communications
• Focus on the future
• Business plans goals
• Analysis of informing needs What data is needed,
  what system outputs are needed, who/when/where
  needs them.
• Tool for requirement analysis is System Accept.

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Design System

• Designing system is about creating a new IS or a
  major upgrade of an existing IS.
• The data model is created or changed in case of
  upgrade.
• The processing of data in the system is defined
  according to the model of organizational process
  resulting from the System Analysis step.
• User Interface is designed (content and look of
  screens, their sequence).
• User interface is the point of connection between
  User and System, and thus it determines
  expenditures of users time and effort
  productivity factors.
• Design tools include ArgoUML, AstahUML, Visio,
  SmartDraw etc

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Construct System

• A system is physically made based on the design
  created (data diagrams, and process diagrams that
  determine what software should do how the data
  should be processed).
• This includes several activities
• Write application software (computer programming)
• Buy application software (off-the-shelf software)
• Purchase computer and other electronic hardware

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Install Test System

• Installation Software is mounted on hardware,
  cabling completed, and facilities prepared. This
  may happen gradually in iterative development.
• Testing Evaluating the performance of a
  developed system.
• Kinds of tests run based on moving from small to
  large
• Unit testing (experts test an individual function
  a system performs e.g., set a credit limit for a
  customer, create a customer order, test
  relationship between the order amount credit
  limit). Test two related units, and keep adding
  new ones.
• System testing (experts test all functions also,
  how much load can an IS take).
• Acceptance testing (final testing performed by
  users includes all components).

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Maintain System in Production Stage

• IS is used in organizational operations (use
  period or production stage).
• IS is evaluated (how many employees use it, how
  well it supports work, costs, business benefits).
  
• As IS is used and managed, its development
  continues in small this is called system
  maintenance.
• System maintenance is incremental development
  performed in the use period of an IS. It
  includes
• De-bugging software (correcting errors in
  software)
• IS modifications based on business needs (e.g.,
  larger data storage needed or reports answering
  new business questions)

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S u m m a r y

• System development process takes activities of
  planning, analysis, designing, constructing,
  installing, testing, and deploying, and
  maintaining an IS.
• Systems are developed in two ways waterfall and
  iterative.
• Plan for new IS can aim at optimizing process
  design, improving process performance, and
  creating new processes.
• System Analysis focuses on both business and
  existing IS (if any) to understand how work is
  done and how it should be.
• Well-designed IS should perform work needed, be
  easy to learn and use, and enable efficient
  (quick ) work.
• IS construction implements IS design, where
  software can be created in different ways.
• There are 3 methods of IS testing and 3
  deployment strategies.
• System maintenance continues throughout the
  system use period.