Explain The Requirements Validation Process
Requirements validation is concerned with showing that the requirements actually define the system that the customer wants. Requirements validation overlap analysis in that it is concerned with finding problems with the requirements. Requirements validation is important because errors in a requirements document can lead to extensive rework costs when they are discovered during development or after the system is in service. The cost of fixing a requirements problem by making a system change is much greater than repairing design or coding errors. The reason for this is that a change to the requirements usually means that the system design and implementation must also be changed and then the system must be tested again.
During the requirements validation process, checks should be carried out on the
requirements in the requirements document. These checks include:
Validity checks A user may think that a system is needed to perform certain functions. However, further thought and analysis may identify additional or different functions that are required. Systems have diverse stakeholders with distinct needs, and any set of requirements is inevitably a compromise across the stakeholder community.
Consistency checks Requirements in the document should not conflict. That is there should be no contradictory constraints or descriptions of the şame system function.
Completeness checks The requirements document should include requirements, which define all functions, and constraints intended by the system user.
Realism checks Using knowledge of existing technology, the requirements should be checked to ensure that they could actually be implemented. These checks should also take account of the budget and schedule for the system development.
Verifiability To reduce the potential for dispute between customer and contractor, system requirements should always be written so that they are verifiable. This means that you should be able to write a set of tests that can demonstrate that the delivered system meets each specified requirement.
A number of requirements validation techniques can be used in conjunction or individually:
1. Requirements review The requirements are analyzed systematically by a team of reviewers. This process is discussed in the following section.
2. Prototyping In this approach to validation, an executable model of the system is demonstrated to end-users and customers. They can experiment with this model to see if it meets their real needs.
3.Test-case generation Requirements should be testable. If the tests for the requirements are devised as part of the validation process, this often reveals requirements problems. If a test is or impossible to design, this usually means that the requirements will be difficult to implement and should be reconsidered. Developing tests from the user requirements before any code is written is an integral part of extreme programming.
You should not underestimate the problems of requirements validation. It is difficult to show that a set of requirements meets a user’s needs. Users must picture the system in operation and imagine how that system would fit into their work. It is hard for skilled computer professionals to perform this type of abstract analysis and even harder for system users. As a result, you rarely find all requirements problems during the requirements validation process. It is inevitable that there will be further requirements changes to correct omissions and misunderstandings after the requirements document has been agreed upon.