The document summarizes an article that provides an overview of goal-driven approaches to requirements engineering. It describes how goal-driven approaches focus on the intentional relationship between the usage world and system world to define user-defined requirements based on the goals and objectives of developing the system. The document then outlines some advantages and disadvantages of the goal-driven approach, and provides details on the L'Ecritoire tool that links goals to scenarios to elicit and specify requirements through "requirement chunks". It concludes by summarizing the main advantages of taking a goal-driven approach to requirements engineering.

1. Eugenio MAURI 10/03/2011
MSIC JB 2011 (UE02 - Ingénierie des exigences)
Summary of the article “Reasoning with goals to engineer requirements (Colette Rolland)”
In this article the author gives an overview of various researches on the subject of “goal-
driven approaches”, oriented to requirements engineering field.
She focuses on the “L’Ecritoire” approach to present the state of the art and starts by
reminding that all goal driven approaches, ultimately, aim at building purposeful system
requirements that meet their users’ expectations but also the objectives of different
stakeholders.
Researches pointed out that since requirements arise from the “subject world” (e.g.: the
part of the world on which to provide information) the “usage world” (e.g.: agents’
procedures) and the “system world” (e.g.: the world dictated by system specifications
where requirements coming from the other two worlds must take place) the relationships
that link these systems define different types of requirements.
The “representation relationship” (between subject and system world) address domain-
imposed requirements while “intentional relationship” (between usage world and system
world) address user-defined requirements.
Since the latter explains “why” the system is developed (therefore is the link between the
system and the goals and objectives of the organisation.) all goal-driven approaches focus
on it.
As the author says, this point is quite important since, throughout the whole article, she
stresses the fact that the real purpose of building a system is not to be found inside the
system itself but in the enterprise, which means in a more global context and that all goal-
driven approaches focus on the intentional relationship.
The reading goes on by illustrating some of the advantages of focusing on goals, such as
goals refinement (for exploration of choices), requirements pre-traceability and
justification to stakeholders, conflicts detection, etc..
On the other hand, an overview of drawbacks and issues is also given: problems
mentioned are those such as the definition of the “goal” concept itself, or the fact that
sometimes systems are build with not precise goals in mind, or the fact that sometimes
goals are idealized or not complete or the fact that goal decomposition can be tricky.
An insight is given to the “L’Ecritoire” approach to see how it deals with the above issues
in order to elicit, specify and document requirements.
L’Ecritoire is a tool that produces a requirement document by coupling goals and
scenarios (described as one ore more actions describing a path from two states of agents)
derived by analysing textual scenarios.

2. The couple goal-scenario (named “requirement chunk”) is the central point if this
approach and represent a possible way to achieve a given goal. By moving from goals to
scenarios, and vice versa, this approach allows for both goals discovery and requirements
elicitation process.
The author then goes a bit into details concerning the mechanism on which goal
formulation is based inside the L’Ecritoire tool: a combinations of verbs and parameters
that can designate a mean, a manner, an agent, etc…
This in order to quickly introduce the concepts of informal, semi-formal and formal
specifications and the reasons behind them (e.g.: automatic analysis) and skim through
some other existing tool and approaches, such as Kaos or Electra.
The concept of composition, alternative and refinements are also detailed, and the
resulting structure organised in “AND”, “OR” and different “granularities” is presented.
A brief panoramic of some possible relationships between goals follows, showing the
possibility for conflict and positive/negative influence.
Relationship between goals and agents is also sketched, and also between other entities,
such as problems, opportunities, threads or obstacles.
The concept of abstractions is presented, with its different types (behavioural, functional,
physical) defining goals at different levels (e.g.: from strategic to technical).
Finally, “goal discovery” and “scenario authoring” strategies are presented but the article
goes into details only on the “discovery rules” implemented by L’Ecritoire (pointing the
reader few other papers that go deeper into the scenario authoring part); an example of a
rule is illustrated, based on refinement strategy and the “WHY/WHAT IF” and “HOW”
techniques are also mentioned.
Few references to other papers on different way to approach this aspect are given to the
reader.
In the end the author summarizes all the benefit from goal-driven RE that lead to the
rationale to the system to be built.
As a conclusion of the article, the author tries to quickly summarise all the advantages
brought by goal-driven RE, namely: provide the rationale for the system to be built,
provide a link between the system and the context, facilitate business changing translation
into features of the system, highlight choices and alternatives, help finding requirements,
facilitates mapping between goals and specs, facilitates goals negotiation, helps finding
conflicts and fixing them.
Some other advantages are also possible and the author points the reader to some other
papers that give more details about them.