How to assess the quality of a requirements specification.

1. Requirementsquality A theoreticalintroduction

2. Contents 2 Currentsituation in swdevelopment Whyrequirements are so important Whatisthequality target ARM project RequirementsQualityAnalyzer: RQA Requirements quality (A theoretical introduction) - (C) The REUSE Company

3. Currentsituation in sw. development Requirements quality (A theoretical introduction) - (C) The REUSE Company 3

4. Whyrequirements are so important Requirements quality (A theoretical introduction) - (C) The REUSE Company 4 Based on requirements 15.9% 13.0% 8.2 % 2.9 % +40% directly related to requirements

5. Whyrequirements are so important Requirements quality (A theoretical introduction) - (C) The REUSE Company 5 Requirements: Should be signed as a contractbetweendeveloper and customer Are thebasisfor software design Man role alsoduringthetestingphase

6. Whyrequirements are so important Requirements quality (A theoretical introduction) - (C) The REUSE Company 6 Software projects are more and more complexoverthe time The sooner a problemistackledthelessthesolutioncosts

7. Whatisthequality target Requirements quality (A theoretical introduction) - (C) The REUSE Company 7 Accordingto IEEE Std. 830 – 1998: Correct Unambiguos Complete Consistent Ranked (importance and stability) Verifiable Modifiable Traceable

8. Whatisthequality target Requirements quality (A theoretical introduction) - (C) The REUSE Company 8 According to ESA PSS-05-03: SR04 Each software requirement shall include an identifier. SR05 Essential software requirements shall be marked as such. SR06 For incremental delivery, each software requirement shall include a measure of priority so that the developer can decide the production schedule. SR07 References that trace software requirements back to the URD shall accompany each software requirement. SR08 Each software requirement shall be verifiable. SR11 The SRD shall be complete. SR12 The SRD shall cover all the requirements stated in the URD. SR13 A table showing how user requirements correspond to software requirements shall be placed in the SRD. SR14 The SRD shall be consistent. SR15 The SRD shall not include implementation details or terminology, unless it has to be present as a constraint. SR16 Descriptions of functions ... shall say what the software is to do, and must avoid saying how it is to be done. SR17 The SRD shall avoid specifying the hardware or equipment, unless it is a constraint placed by the user.

9. Whatisthequality target Requirements quality (A theoretical introduction) - (C) The REUSE Company 9 "I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to Earth"

10. Whatisthequality target Requirements quality (A theoretical introduction) - (C) The REUSE Company 10 Allthese targets seemto be clear RM tools (e.g. DOORS or IRQA) helpus in some cases: Modifiable, traceable… But, letusdoublecheckthese targets Are allthesequalitygoalsreallyunambiguous Spanishproverb: «In theblacksmith’s home woodenknife»

11. ARM project Requirements quality (A theoretical introduction) - (C) The REUSE Company 11 ARM: AutomatedRequirementMeasurementby NASA «The objective of the ARM toolistoprovidemeasuresthat can be usedbyproject managers toassessthequality of a requirementsspecificationdocument» The ARM tool scans a requirements specification document for key words and phrases and generates a report file summarizing the specific quality indicators The tool is not intended to evaluate the correctness of the specified requirements; it’s an aid to “writing the requirements right”, not “writing the right requirements” ARM analyzes a whole specification, req by req, and is able to show which aspects of a requirement should be avoided

12. ARM project Requirements quality (A theoretical introduction) - (C) The REUSE Company 12 Objectivelymeasuredindicators vs. qualityattributes

13. Requirements Quality Analyzer Requirements quality (A theoretical introduction) - (C) The REUSE Company 13 RQA (Requirements Quality Analyzer) is a toolby The REUSE Company In thesameway as ARM, RQA try toobtainobjectivequalitymeasurements RQA works, nowadays, in English and Spanish The maindifferencesbetween RQA and ARM: RQA includesmuch more metricsthat ARM RQA isfullyconnectedtoDOORS and IRQA RQA isfullycustomizable RQA uses linguisticcapabilities and notkeywordspotting RQA uses semanticcapabilitiestoprovide global metrics RQA allowsyou cicles of changetext and assessquality as many times as needed

14. Requirements Quality Analyzer Requirements quality (A theoretical introduction) - (C) The REUSE Company 14 More informationaboutRequirements Quality Analyzer: http://www.reusecompany.com