Software Engineering: Characteristics of Good Requirements Definition & Specification, Study Guides, Projects, Research of Software Engineering

Download Software Engineering: Characteristics of Good Requirements Definition & Specification and more Study Guides, Projects, Research Software Engineering in PDF only on Docsity! 1 Slide 1CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 REQUIREMENTS DEFINITION & SPECIFICATION Slide 2CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Requirements definition and specification • Must correctly define all of the software requirements, but no more • Should not describe any design, verification, or project management details, except for required design constraints Slide 3CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Characteristics of Good RD&S • Unambiguous • Complete • Verifiable • Consistent • Modifiable • Traceable • Usable during the operation and maintenance phase 2 Slide 4CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Characteristics of Good RD&S (Contd) • Unambiguous • Every requirement has only one interpretation • Each characteristic is described using only one term • Example of ambiguous requirement: All customers have the same control field a) All customers have the same value in their control fields b) All customers control fields have the same format c) One control field is issued for all customers Slide 5CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Characteristics of Good RD&S (Contd) • Complete • Inclusion of all significant functional and non-functional requirements • Specification of the responses to valid and invalid input values • Conformity to any standard that applies • Full labeling and referencing of all figures, tables, and diagrams and definition of all terms and units of measure • Any RD&S that uses the phrase to be determined (TBD) is not complete Slide 6CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Characteristics of Good RD&S (Contd) • Verifiable • There exists some finite cost-effective process which a person or machine can check that the software product meets the requirements • Examples of non-verifiable requirements statements o The product should work well o The output of the program shall usually be given within 10 s 5 Slide 13CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Partitioning • Problems are usually too large and complex • Partition (divide, decompose) the problem into parts • Establish interfaces between parts • Decompose the problem functionally by moving horizontally in the hierarchy • Expose increasing level of detail by moving vertically in the hierarchy Slide 14CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Example of partitioning • SafeHome software enables the homeowner to configure the system when it is installed, monitors all sensors connected to the security system, and interacts with the homeowner through a keypad and function keys contained in the SafeHome control panel Slide 15CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Horizontal partitioning - functions SafeHome software Monitor sensorsConfigure system Interact with user 6 Slide 16CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Vertical (hierarchical) partitioning - details SafeHome software Monitor sensorsConfigure system Interact with user Poll for sensor event Activate alarm functions Identify event type Read sensor status Activate / deactivate sensor Activate audible alarm Dial phone number Slide 17CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Software Requirements Specification • developed as a consequence of analysis • review is essential to ensure that the developer and the customer have the same perception of the system • even with the best of methods, the problem is that the problem keeps changing Slide 18CS 230 Introduction to Software EngineeringCopyright © K.Goseva 2006 Sample Formats • Based on the IEEE Standard 830: Software Requirements Specifications • Requirements Definition • Requirements Specification