1 A Framework for Measurement Valérie Paulus, Miguel Lopez, Gregory Seront, Simon Alexandre

Workshop on Software Metrics Validation - 6th of July Presentation of the Framework Aim of the framework : –To highlight the different activities involved in the process –To highlight the different products related to these activities –To organize the activities to undertake to achieve a measurement task –To understand and evaluate the existing structure The work is based on : –The process model proposed by Abran & Jacquet (1997) –The validation framework of Kitchenham & al (1995) –The validation approach proposed by Lopez & al (2003) –The vocabulary of metrology proposed by ISO (1993) Allows to refine knowledge we have on the attribute to measure by the possibility to come back to the beginning of the process

Workshop on Software Metrics Validation - 6th of July Presentation of the Framework Measurement Result Exploitation Measurement Method Design Measurement Method Application V&V

Workshop on Software Metrics Validation - 6th of July Measurement Method Design 1. Defining the context 2. Modelling the empirical model 1. Characterizing the model to be used 2. Characterizing the entity 3. Characterizing the attribute to be measured 3. Defining a numerical model 4. Defining mapping rules

Workshop on Software Metrics Validation - 6th of July Measurement Method Design Measurement method takes place in an empirical situation The context of this situation has to be deeply defined Which parameters : –The goal of the measurement –The constraints of the measurement : oMaturity of our knowledge of the attribute to measure oExisting measuring instrument oUsed measuring instrument o…

Workshop on Software Metrics Validation - 6th of July Measurement Method Design 1. Defining the context 2. Modelling the empirical model 1. Characterizing the model to be used 2. Characterizing the entity 3. Characterizing the attribute to be measured 3. Defining a numerical model 4. Defining mapping rules

Workshop on Software Metrics Validation - 6th of July Measurement Method Design To elaborate a model that represents the knowledge of practitioners about the entity and the attribute under consideration To make operational the intuitive view practitioners have Traditional view : –A set of entities [A] –A collection of binary relation [R i ] –A collection of operators [O i ] Incomplete for practical measurement method –What about ordering the elements of the set A ? –What about operation, transitivity, strongly completeness ? We propose to base the design on formal and operational view by using the notion of meta model –See last presentation

Workshop on Software Metrics Validation - 6th of July Measurement Method Design 1. Defining the context 2. Modelling the empirical model 1. Characterizing the meta-model to be used 2. Characterizing the entity 3. Characterizing the attribute to be measured 3. Defining a numerical model 4. Defining mapping rules

Workshop on Software Metrics Validation - 6th of July Measurement Method Design The framework allows large spectrum of modelling languages and approaches Distinction is done between : –The modelling part –The modelling techniques The choice is made based on the essence of the attribute and the entity to measure

Workshop on Software Metrics Validation - 6th of July Measurement Method Design 1. Defining the context 2. Modelling the empirical model 1. Characterizing the model to be used 2. Characterizing the entity 3. Characterizing the attribute to be measured 3. Defining a numerical model 4. Defining mapping rules

Workshop on Software Metrics Validation - 6th of July Measurement Method Design The goal of design phase is to build the model of the entity to measure But the constructed model of the entity has the aim to highlight the particular attribute to be measured The created abstraction aims to highlight the particular attribute to measure by ignoring others For example : –Coupling measure oBased on UML graph for OO programs –Complexity measure oGraph representation of algorithms –Functional size attribute in the Cosmic FFP oModelling of the FUR with highlighted processes

Workshop on Software Metrics Validation - 6th of July Measurement Method Design 1. Defining the context 2. Modelling the empirical model 1. Characterizing the model to be used 2. Characterizing the entity 3. Characterizing the attribute to be measured 3. Defining a numerical model 4. Defining mapping rules

Workshop on Software Metrics Validation - 6th of July Measurement Method Design The entity is now well circumscribed We had to define the characteristics of the attribute to measure The attribute itself has to be well defined (it is not currently the case) –What’s coupling or complexity or size of programs ? Methods –Assertion of rules as transitivity, completeness, non negativity –To give a representational set of the entities and to order this set in the view of the attribute to measure ( done by experts) –To give the way the attribute is composed by other (if the attribute is a derived one)

Workshop on Software Metrics Validation - 6th of July Measurement Method Design 1. Defining the context 2. Modelling the empirical model 1. Characterizing the model to be used 2. Characterizing the entity 3. Characterizing the attribute to be measured 3. Defining a numerical model 4. Defining mapping rules

Workshop on Software Metrics Validation - 6th of July Measurement Method Design Definition of measurement : –A mapping of the empirical world into a numerical one Definition of the mathematical structure –A set with a collection of defined operations on it –To do with the notion of scale and scaling transformation Mathematical structure includes operation –Notion of distance between elements Definition of actual values (for example the zero value) Definition of standards/etalons –See the presentation of Gregory

Workshop on Software Metrics Validation - 6th of July Measurement Method Design 1. Defining the context 2. Modelling the empirical model 1. Characterizing the model to be used 2. Characterizing the entity 3. Characterizing the attribute to be measured 3. Defining a numerical model 4. Defining mapping rules

Workshop on Software Metrics Validation - 6th of July Measurement Method Design Definition of the practical rules needed to map the empirical elements into the numerical world Define the operational process to follow to achieve the measurement For example : –Counting : what is kept or reject, how to count … –Calculation : rules of computing, definition of equation –Utilisation of instrument : description, calibration …

Workshop on Software Metrics Validation - 6th of July Measurement Method Application 1. Constructing a model of the entity to measure 2. Applying the measurement rules and calibration of the instrument

Workshop on Software Metrics Validation - 6th of July Measurement Result Exploitation Could include several aspects : –Measurement analysis oDetection of anomalies oAnalyse for the supposed usage –Quality prediction –Quality assessment –Quality control Allows the comparison of measurement on different programs

Workshop on Software Metrics Validation - 6th of July Validation and Verification Measurement Result Exploitation Measurement Method Design Measurement Method Application V&V

Workshop on Software Metrics Validation - 6th of July Questions ?