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Guideline (Beginner,Concept) Don’t mix Goals and Tasks in the Means-Ends links. Open Version
Discussion: Goals are different than Tasks, and therefore can’t be mixed in Means-Ends Links. A Goal is an Actor’s End desire, not a Means to achieve this End desire (Goal). In i* framework, An End desire (Goal) is achieved via a Task, which is a Means to achieve the End desire or a Goal. See Section 5.2 “Elements/Nodes” for more explanation about Goals and Tasks. Figure 1 depicts an example where the Means-Ends Links is allowed and where it is not. See the guideline in section 5.2.1 “Goals (Hard Goals)” for an example of using the Means-Ends Link and Task notations to indirectly decompose Goals to sub-goals.
Note: The i* Means-Ends Link notation is not to be confused with a similar notation used by Tropos methodology to denote an OR decomposition of Goals. Figure 2 (troposproject.org) depicts Tropos notation for both AND and OR decomposition notation. It can be noticed that Tropos allows direct decomposition of Goals to sub-goals. On the other hand, i* decomposes Goals into sub-goals indirectly using the Task notation as shown in Section 3 “Summary of i* Notation” and discussed in Section 5.4 “Decomposition Links”. The i* notation of Goal decomposition encourages the modeler to consider distinctions among Goals, Softgoals, Tasks, and Resources are each step of decomposition.
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