Statistical test based model in software engineering
- 1. CLEANROOM SOFTWARE DEVELOPMENT MODEL Enhancing the software quality BY YASH PRASHANT PUROHIT-20MIS0364
- 2. INTRODUCTION • Developed by Dr. Harlan Mills (IBM) in 1981 • An incremental development model • Small increments which reduces the complexity of the system • The Clean Room software engineering follows a quality approach to software development which follows a set of principles and practices for gathering requirements, designing, coding, testing, managing, etc. which not only improves the quality of the product but also increases productivity and reduces development cost.
- 3. Unlike the traditional approach where the Quality Assurance is performed at the end of the development process, in cleanroom engineering, Quality Assurance is performed at each and every phase of software development. From the beginning till the completion, we focus on preventing defects rather than removing them. It has a mathematical based approach to pursue the software specifications and the development process
- 4. CLEANROOM DEVELOPMENT PROCESS FUNCTIONS 1. Specification team: Consists of requirement analysis, function specification, usage specification, incremental planning 2. Development team: Consists of software reengineering, correctness verification, incremental design etc. 3. Certification team: Final Process of each increment consisting of usage modelling and test planning, statistical testing and certification process etc. 4. Documentation team
- 7. 1. SPECIFICATION • Functional Specification: formal document used to describe a product's intended capabilities, appearance, and interactions with users in detail for software developers. • Usage Specification: a set of use cases that describe user interactions that the software must provide to the user for perfect interaction.
- 8. INCREMENTAL DEVELOPMENT PLANNING • The complex system is divided into smaller pieces and the development process is planned in an incremental manner. • Based on the mathematical principle of referential transparency. • the requirement for referential transparency places constraints on the functional content and order of design decomposition of a software system. User functions are organized for development into a sequence of verifiable and executable software increments, each providing additional function.
- 9. FORMAL DESIGN AND THE BOX APPROACH • Box structure is a modelling approach that is used in clean room engineering. It generally uses three types of boxes i.e. • 1. Black box –It identifies the behaviour of the system. • 2. State box –It identifies state data or operations. • 3. Clear box –It identifies the transition function used by the state box. • Make a formal design in accordance with the specifications. Detailed paperwork and mathematical requirements are frequently a part of this design process.
- 10. TEST CASE GENERATION • Statistical Testing is a testing method whose objective is to work out the undependable software package products instead of discovering errors. check cases are designed for applied mathematics testing with a wholly different objective than those of typical testing. • Testing is based on anticipated customer usage. Test case are designed to rehearse frequently used functions.
- 11. CERTIFICATION AND MTTF • “Mean time to Failure” which is measured in terms of software specific units. • For example, Number of transactions processed successfully for a database product or a banking system.
- 12. EXAMPLES • ReactOS, an open source operating system made from clean-room reverse-engineered components of Windows, and Coherent operating system, a clean room re- implementation of version 7 Unix. • Phoenix Technologies sold its clean-room implementation of the IBM-compatible BIOS to various PC clone manufacturers. • The adoption of Cleanroom thus far is mostly confined to small projects. Like other formal methods , the questions about its ability to be scaled up to large projects and the mathematical training required have been asked by many developers and project managers.
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