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On the Representation of Intangible Objects such as Software in a Measurement ContextPowerPoint Presentation

On the Representation of Intangible Objects such as Software in a Measurement Context

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On the Representation of Intangible Objects such as Software in a Measurement Context

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### On the Representation of Intangible Objects such as Software in a Measurement Context

Miguel Lopez

Valérie Paulus

Grégory Seront

Simon Alexandre

Questions in a Measurement Context

- Are software so intangible that measurement of such abstract beings is impossible?
- Is the nature of software so impalpable?
- How can we formulate the software representation problem in order to allow measurement?

More Questions in a Measurement Context

- Is it relevant to measure software representations in order to make decisions concerning this software?
- Are the representations of software relevant and suitable for measurement?

Software Models in a Measurement Context

- To measure, we need a representation of the software because of its intangible nature.
- The representation of a software is called a model.

Different Software Models in a Measurement Context

- In the literature, a lot of languages for representing software can be found.
- UML
- Graphs
- Source Code
- ….

Software Meta-Model in a Measurement Context

- The concepts and their relations used for building a model are explained in a meta-model.
- So, meta-models exist for UML, graphs, and so on.

Software Meta-Model Problem in a Measurement Context

- How can we select a relevant and suitable meta-model in measurement context?
- Is that always necessary to use meta-models in order to measure a software?
- For an external measure, do we have to work with meta-models?

Meta-model for Measurement in a Measurement Context

- Measure Definition:
- Mapping between an empirical set onto a mathematical set.
- A mapping between an empirical set of objects A and a mathematical set of objects B.

Set B

Set A

Set A Problem in a Measurement Context

- Set A is a set of empirical objects.
- By definition, tangible objects.

- Are software tangible objects?
- Is all the software intangible?
- Or, just some parts, some attributes?

- Some software attributes are intangible.
- Coupling, cohesion, complexity,efficiency,…

Set A Problem in a Measurement Context

- So, to perceive those attributes, they need representation or model.
- Set A is replaced by a set A’ which contains representations of objects of set A.
- The transformation A -> A’ transforms intangible objects into tangible objects.

Set A Problem in a Measurement Context

- Does the transformation A -> A’ keeps the structure of Set A?
- When measuring an element of A’, are we measuring the corresponding element of A?

Set B

Set A’

Set A

Build Set A’ in a Measurement Context

- To build the set of representations or models, we need to define the elements used for modeling.
- These elements are formalized in a meta-model.

Meta-Model in a Measurement Context

- So, the meta-model must be relevant and suitable in regard with:
- Measurement Goal
- Entity: products, projects, process
- Attribute: properties of the entity: efficiency, coupling,…

Measurement Method in a Measurement Context

- A measurement method must at least define:
- Its goal
- The considered entity
- The attribute to be measured

- In regard with these three elements, a suitable and relevant meta-model must be built or selected.

Entity & Meta-model in a Measurement Context

- In this presentation, only the entity software product is considered.
- The meta-modelisation aims at modeling the entity.
- Several types of software product entities exist:
- Requirements Document
- Design Document
- Source Code
- Executable

Entity & Meta-model in a Measurement Context

- The meta-model depends on the type of entity.
- For example:
- Design Document:
- Meta-model of UML: class, relations,…
- Meta-model of graphs: nodes, edges,…

- Design Document:

Entity, Meta-model, & Attribute in a Measurement Context

- But, the meta-model also depends on the type of attribute.
- In regard with the attribute, some meta-models are more relevant and suitable than others.

Entity, Meta-model, & Attribute in a Measurement Context

- For example, measuring the functional size of a software product with Cosmic-FFP:
- Entity: Requirements Document
- Attribute: Functional size

Entity, Meta-model, & Attribute in a Measurement Context

- Meta-Model: Cosmic-FFP

How to verify the meta-model? in a Measurement Context

- Two methods:
- Expert-based: the relevance and the suitability of the meta-model is evaluated by a set of experts.
- Empirical: the relevance and the suitability is of the meta-model is evaluated within a set of entities coming real projects.

How to verify the meta-model? in a Measurement Context

- Problems with these two methods:
- Expert-based:
- Reliability of the experts judgment.
- Representativity of the experts sample.

- Empirical:
- What does mean suitable and relevant in operational terms?
- How can we make representative samples?

- Expert-based:

Advantages to explicit the meta-model in a Measurement Context

- An explicit meta-model allows to better understand the entity and the attribute to be measured.
- To meta-model an entity like design, source code in terms of a given attribute (coupling,…), it is important to understand and clearly define these terms.

Advantages to explicit the meta-model in a Measurement Context

- An explicit meta-model allows to identify early in the measurement method, the limits of measurement:
- Cosmic-FFP meta-model does not take into account the complexity of the data movement.
- So, the software with complex algorithms are not sized by COSMIC-FFP

Meta-model for all types of measurement in a Measurement Context

- Meta-model in external measures are often implicit.
- It is not necessary to explicit the meta-model of the entity for external measures.
- Response time: which is the meta-model of the entity?

Conclusion in a Measurement Context

- Does the entity meta-model a critical activity in software measurement?
- Must this activity be explored in details?

Questions in a Measurement Context

- ?