Implementation and Support

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Implementation and Support

• - Construction, Conversion and Maintenance of the
  New System

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What is Systems Implementation?

• Systems implementation is the construction of the
  new system and the delivery of that system into
  production (meaning day-to-day operation).

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The Construction Phase of Systems Implementation

• The purpose of the construction phase is twofold
  
• To build and test a functional system that
  fulfills business and design requirements, and
• To implement the interfaces between the new
  system and existing production systems.

4
Build and Test Networks

• The purpose of this activity is to build and test
  new networks and modify existing networks for use
  by the new system.
• The key input is the network design requirements
  defined during systems design.

5
Build and Test Databases

• The purpose of this activity is to build and test
  new databases and modify existing databases for
  use by the new system.

6
Install and Test New Software Package

• The purpose of this activity is to install any
  new software packages and make them available in
  the software library.
• The applications programmer will complete the
  installation and testing of the package according
  to integration requirements and program
  documentation that was developed during system
  design.

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Write and Test New Programs

• The purpose of this activity is to write and test
  all programs to be developed in-house.
• If modules are coded top-down, they should be
  tested and debugged top-down and as they are
  written.

8
Testing a New Program

• There are three levels of testing to be
  performed stub testing, unit or program testing,
  and systems testing.
• Stub testing is the test performed on individual
  modules, whether they be main program,
  subroutine, subprogram, block, or paragraph.
• Unit or program testing is a test whereby all the
  modules that have been coded and stub tested are
  tested as an integrated unit.
• Systems testing is a test that ensures that
  application programs written in isolation work
  properly when they are integrated into the total
  system.

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The Delivery Phase

• Conduct a system test to ensure that the new
  system works properly.
• Install databases to be used by the new system.
• Provide training and documentation for
  individuals that will be using the new system.
• Prepare a conversion plan to provide a smooth
  transition to the new system.
• Convert from the old system to the new system and
  evaluate the project and final system.

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Conduct System Test

• The purpose of this activity is to test all
  software packages, custom-build programs, and any
  existing programs that comprise the new system to
  ensure that they all work together.

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Install Databases

• The purpose of this activity is to populate the
  new systems databases with existing data from the
  old system.

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Train System Users

• Provide training and documentation to system
  users to prepare them for a smooth transition to
  the new system.

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Conversion

• Prepare a detailed conversion plan to provide a
  smooth transition from the old system to the new
  system.
• Convert to the new system from the old system and
  evaluate the project experience and final system.

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Common conversion strategies

• Plunge (Direct Changeover)
• Parallel conversion
• Phased (Gradual) conversion
• Pilot (Modular prototype) conversion typically
  in a single location

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What is Systems Support?

• Systems support is the on-going maintenance of a
  system(s) after it has been placed into
  operation. This includes program maintenance and
  system improvements.
• Systems support often requires developers to
  revisit activities typically performed in systems
  analysis, design, and implementation.

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Systems Maintenance - Correcting Errors

• Regardless of how well designed, constructed, and
  tested a system or application may be, errors or
  bugs will inevitably occur.
• The correcting of bugs is called system
  maintenance, or program maintenance.

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System Recovery - Overcoming the Crash

• A system failure is inevitable.
• It generally results in an aborted or hung''
  program (also called an ABEND'' or crash'')
  and possible loss of data.
• The systems analyst often fixes the system or
  acts as intermediary between the users and those
  who can fix the system.

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Database Backup and Recovery

• Data in a database may be lost or corrupt by
  invalid or partial update due to the crash.
• Backup/Recovery Techniques
• Roll back logging (taking a backup copy) of
  before-image (image of DB before the
  transaction), and rollback the image when data
  are lost.
• Roll forward perform transaction on the image
  (master is intact), upon successful transaction,
  dump the image onto the master (roll forward).

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End-User Assistance

• No matter how well users have been trained or how
  well documentation has been written, users will
  require additional assistance.
• The systems analyst is generally on call to
  assist users with the day-to-day use of specific
  applications.

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Systems Enhancement and Reengineering

• Adapting an existing system to new requirements
  is an expectation for all newly implemented
  systems.
• Adaptive maintenance forces an analyst to analyze
  the new requirement and return to the appropriate
  phases of systems analysis, design, and
  implementation.

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The Year 2000 and Systems Support

• The year 2000 problem was the potential of
  triggering widespread computer application
  disasters across many corporations.