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The V-model is a term applied to a range of models, from a conceptual model designed to produce a simplified understanding of the complexity associated with systems development to detailed, rigorous development lifecycle models and project management models. There are several radically different forms of the V-model, and this creates considerable confusion. The V-model falls into three broad categories.〔("The Dangerous & Seductive V Model" ), accessed January 9, 2013〕 Firstly there is the German V-Model "Das V-Modell", the official project management methodology of the German government. It is roughly equivalent to PRINCE2, but more directly relevant to software development.〔("Das V-Modell site (in German)" ), accessed January 9, 2013〕 What is probably the earliest use of the V-Model as a basis for a standard is Software Development Standard for the German Federal Armed Forces, 1992. The key attribute of using a "V" representation was to require proof that the products on the right-side of the V were acceptable by the appropriate test and integration organization implementing the left-side of the V. In the UK, and throughout the testing community worldwide, the V-model is widely seen as a vaguer, illustrative depiction of the software development process, as described in the ISTQB Foundation Syllabus for software testers.〔("International Software Testing Qualifications Board – Foundation Level Syllabus" ), accessed January 9, 2013〕 There is no single, accepted definition of this model, which is more directly covered in the alternative article on the V-Model (software development). There are therefore multiple variations of this version. This problem must be borne in mind when discussing the V-model. Thirdly, like Germany, the US also has a government standard V-model, which dates back about 20 years, like its German counterpart. Its scope is rather narrower, being a systems development lifecycle model, but far more detailed and more rigorous than most UK practitioners and testers would understand by the V-model.〔("US Dept of Transportation, Federal Highway Administration. Systems Engineering Guidebook for ITS" ), accessed January 9, 2013〕〔Forsberg, K., Mooz, H., Cotterman, H. ''Visualizing Project Management,'' 3rd edition, John Wiley and Sons, New York, NY, 2005. Pages 108-116, 242-248, 341-360.〕〔International Council On Systems Engineering (INCOSE), ''Systems Engineering Handbook Version 3.1,'' August 2007, pages 3.3 to 3.8〕 == Overview == The V-model is a graphical representation of the systems development lifecycle. It summarizes the main steps to be taken in conjunction with the corresponding deliverables within computerized system validation framework. The ''V'' represents the sequence of steps in a project life cycle development. It describes the activities to be performed and the results that have to be produced during product development. The left side of the "V" represents the decomposition of requirements, and creation of system specifications. The right side of the ''V'' represents integration of parts and their validation.〔〔〔(【引用サイトリンク】 The SE VEE )〕〔Forsberg, K. and Mooz, H., "(The Relationship of Systems Engineering to the Project Cycle )," First Annual Symposium of the National Council On Systems Engineering (NCOSE), October 1991〕 However, Requirements need to be validated first against the higher level requirements or user needs. Furthermore, there is also something as validation of system models (e.g. FEM). This can partially be done at the left side also. To claim that validation only occurs at the right side may not be correct. The easiest way is to say that verification is always against the requirements (technical terms) and validation always against the real world or the user needs. It is sometimes said that validation can be expressed by the query "Are you building the right thing?" and verification by "Are you building it right?" In practice, the usage of these terms varies. Sometimes they are even used interchangeably. The PMBOK guide, an IEEE standard (jointly maintained by INCOSE, the Systems engineering Research Council SERC, and IEEE Computer Society) defines them as follows in its 4th edition: * "Validation. The assurance that a product, service, or system meets the needs of the customer and other identified stakeholders. It often involves acceptance and suitability with external customers. Contrast with ''verification''." * "Verification. The evaluation of whether or not a product, service, or system complies with a regulation, requirement, specification, or imposed condition. It is often an internal process. Contrast with ''validation''." 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「V-Model」の詳細全文を読む スポンサード リンク
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