Implementation

• Purpose of system implementation

  This is has the new system will be deployed, installed; and become fully operational, referring to the hardware, Software and personnel resources that are needed to Implementation
• Implementation


  1. Focuses on using the designs From the previous stage

  2. Constructing the working computer system

  3. Modules to be used

  4. Main data Structures within program code

  5. Main algorithims to be used (Structure diagrams or pseudocode)

  6. Production of the program code
• Resources needed to support the implementation stage

  • Hardware (computer equipment, consumables)
  • Software (operating system, application software, licenses)
  • Personnel (software developers, data processing clerks, technical staff, training experts)
• Methods of Changeover


  • Direct
  • Parallel
  • Pilot
  • Phased
• Direct Changeover


  Organisation stops using old system one day and starts using new one the next day. No time is wasted running 2 systems, there is no overlap between the old + new systems
• Direct Changeover


  • Advantages: New system is up and running immediately, no additional costs with duplicating data processing

  Disadvantages: No backup if the new system fails, no means of comparison between the new and old system
• Parallel Changeover


  Old and new systems operate side by side. When the new system is deemed to be meeting all requirements, the old one is dropped. This may take months
• Parallel Changeover


  • Advantages: The old system is available if the new one fails, new system output and old system output can be compared

  Disadvantages: Increased workload as all data processing must be duplicated on both systems
• Phased Changeover


  Users are gradually transferred to the new system, allowing gradual installation and staff training
• Phased Changeover


  • Advantages: Allows end users to become familiar with the new system

  Disadvantages: If the new system fails in the transitional phase, no backup is available
• Pilot Changeover


  Similar to phased changeover, but only some data from the old system is processed by the new system. The old system operates alongside the new system. Users provide feedback and the new system can be modified.
• Pilot Changeover


  • Advantages: If the new system fails, usually only one department is affected, data processed by the old and new systems can be compared, staff involved can train other members of staff

  Disadvantages: Duplication of resources, can be hard to identify a suitable department, the ability of the new system to process all data is not tested
• Sections contained in User Documentation

  • Installation Instructions
  • HW + SW configuration
  • User guide
  • Help section/FAQ/Tutorial
• User Documentation


  Produced for end-users who are assumed not to be IT professionals with limited understanding of IT terminology
• How user documentation can be provided

  Printed hard copy, embedded into the actual application in multimedia format, on screen in the form of tips and tutorials
• Technical Documentation


  Describes how the system works, written for IT professionals rather than the user, the reader will need expert IT knowledge
• Sections contained in Technical Documentation

  • System/module specification
  • HW and SW configuration
  • Program documentation/Pseudocode/Code
  • DFD/ERD/DB Structure
  • Test Schedule/test data
• Data Conversion


  Data is taken from an existing system and converted into a suitable format. Non-electronic data may have to be converted into electronic format. Data held on certain file forms may need to be changed.
• Maintenance


  The modification of a software application to ensure it continues to run smoothly following implementation. Its purpose is to ensure the system can meet the changing requirements of the organisation.
• Types of Maintenance


  • Corrective
  • Adaptive
  • Perfective
• Corrective Maintenance


  Action taken following system failure after the system is delivered to the end-user. Essentially fixing errors and bugs identified.
• Corrective Maintenance


  • Advantages: Errors and bugs identified will be corrected and the system will run as required

  Disadvantages: Cannot be carried out by the user, specialist staff are needed, usually the team that wrote the original system
• Adaptive Maintenance


  User requirements may change after the system has been in use for some time. This may be due to internal or external changes.
• Adaptive Maintenance


  • Advantages: Additional functionality will be added

  Disadvantages: Cannot be carried out by the user, special staff are needed, usually the team that designed and wrote the original system
• Perfective Maintenance


  Improving the system by removing inefficiencies. The system may meet user requirements, however, the performance may need improving. This could be to take advantage of new hardware and software, or improve processing.
• Perfective Maintenance


  • Advantages: The performance of the system will be improved

  Disadvantages: Cannot be carried out by the user, special staff are needed, usually the team that designed and wrote the original system
• Maintenance is required even when a system has been fully tested in development because user requirements may change over time, and the system may need corrective, adaptive, or perfective maintenance to continue running smoothly.