Validation: Are we building the right system?. Verification: Are we building the system right?

Validation is concerned with checking that the system will meet the customer’s actual needs. Verification will help to determine whether the software is of high quality, but not if it is useful.

Many different V&V tools are already in use at most climate modelling labs, but there is room for adding more tools to the toolbox, and for sharpening the existing tools. But the question of how best to do this must proceed from a detailed analysis of current practices and how effective they are.

V&V tasks during different phases of development lifecycle:

• Planning:
  –  Verification of contract
  –  Evaluation of Concept document
  –  Performing risk analysis
• Requirement phase
  –  Evaluation of software requirements
  –  Evaluation / analysis of the interfaces
  –  Generation of systems test plan
  –  Generation of Acceptance test plan
• Design Phase
  –  Evaluation of software design
  –  Evaluation / Analysis of the Interfaces (UI)
  –  Generation of Integration test plan
  –  Generation of Component test plan
  –  Generation of test design
• Implementation Phase
  –  Evaluation of source code
  –  Evaluation of documents
  –  Generation of test cases
  –  Generation of test procedure
  –  Execution of Components test cases
• Test Phase
  –  Execution of systems test case
  –  Execution of acceptance test case
  –  Updating of traceability metrics
  –  Risk analysis
• Installation and checkout phase
  –  Audit of installation and configuration
  –  Final test of the installation candidate build.
  –  Generation of final test report
• Operation Phase
  –  Evaluation of new constraint
  –  Assessment of the change proposed
• Maintenance Phase
  –  Evaluation of the anomalies
  –  Assessment of migration
  –  Assessment of the retrial features
  –  Assessment of proposed change.
  –  Validating the production issues.

Conclude: V&V processes determine whether products of

Is the modification of a software product after delivery to correct faults, to improve performance or other attributes.

There are number of reasons, why modifications are required, some of them are briefly mentioned below:

• Market Conditions: Policies, which changes over the time, such as taxation and newly introduced constraints like, how to maintain bookkeeping, may trigger need for modification.
• Client Requirements: Over the time, customer may ask for new features or functions in the software.
• Host Modifications: If any of the hardware and/or platform (such as operating system) of the target host changes, software changes are needed to keep adaptability.
• Organization Changes: If there is any business level change at client end, such as reduction of organization strength, acquiring another company, organization venturing into new business, need to modify in the original software may arise.

Types of maintenance

In a software lifetime, type of maintenance may vary based on its nature. It may be just a routine maintenance tasks as some bug discovered by some user or it may be a large event in itself based on maintenance size or nature.

• Corrective Maintenance: This includes modifications and updations done in order to correct or fix problems, which are either discovered by user or concluded by user error reports.
• Adaptive Maintenance: This includes modifications and updations applied to keep the software product up-to date and tuned to the ever changing world of technology and business environment.
• Perfective Maintenance: This includes modifications and updates done in order to keep the software usable over long period of time. It includes new features, new user requirements for refining the software and improve its reliability and performance.
• Preventive Maintenance: This includes modifications and updations to prevent future problems of the software. It aims to attend problems, which are not significant at this moment but
  
  
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