by Gemma Grau
Phase 3: Generation of alternatives
The key point of this phase is to use the reasoning capabilities
provided by i* in order to explore different ways to carry out the process.
For doing so, the method proposed differentiated steps. First the method is analysed and
modified in order to establish which are the aspects that has to be changed and which
new actors has to be included. Second, the responsibility between the actors is
Guided generation of alternatives.
For generating the alternatives, it is possible to apply two different patterns:
- Pattern 1: Activity responsibility falls into the current actor, which means that the activity responsibility does not change and that this part of the i* model remains equal.
- Pattern 2: Delegate activity responsibility, which can be done in different ways:
- Full responsibility delegation, all the actions of the activity are realized by a different actor
- Shared responsibility delegation, some of the actions are delegated and some other not.
- We remark that, when delegating the responsibilities to another actor, sometimes the new
actor needs something from the source actor and the way round, in this case we can choose
to delegate providing or delegate obtaining.
- At the right we can see how these alternatives are generated, whilst at the left we can see that the different alternatives generated have different actors.
Automatic Generation of Alternatives
It is possible to generate the alternatives automatically, by adding components to the system that fulfil the role of the source actors. The generation of alternatives is done by means of generating all the different combinations of the selected actors. The tool allows stating those actors that won’t take part on the generation by ‘anchoring them’.
The tool also allows stating the maximum number of times the actor will be duplicated.
On the left of the following screenshot we can see that 8 alternatives has been generated automatically, each one with different actors in it.