Goal oriented Flashcards
What is goal oriented design?
It is the conceptualisation of the served system using goals
What is a goal?
A goal is an expression of a state to be achieved or avoided
How to decompose goals?
Make high level goals into lower level goals, split goals into smaller goals to produce a goal hierarchy. May proceed until leaf goals are reached that can be satisfied by a computer based system
How do you detect conflicting goals?
Read through the goals and see if any clash. May be hard if lots of goals.
Re express each goal formally into predicate logical then use a theorem proven to detect it.
How do you resolve a goal conflict?
One way is to return to the stakeholders who own the conflicting goals and see whether they are able to accept a compromise or a new goal, also know as satisficing.
Another might be selecting the goal with the highest priority.
How do you build a goal hierarchy?
Elicit goals from stakeholders then build a hierarchy based on them
Infer the existence of goals
Higher level goals may be inferred from lower level goals
Why are inferred goals useful?
They may help the stakeholders to understand their goals better
They may make explicit what stakeholders think is obvious.
They may provide low level goals from which requirements for a component based system may be directly derived.
Advantages of goal orientated approach
Goals provide rationale for a set of requirements.
Facilitates understanding of a system
Encourages implementations detail independence
Facilities the provision of reusable structures
Goals provide a precise intention of completeness of a requirements specification.
Characterised by a systematic process.
Facilitations the detection and resolution of intrinsic conflict
Facilitates the identification and exploration of alternative solutions
Helps to avoid irrelevant requirements
Provided a starting point for traceability
Facilitates evaluation of system and its design
Disadvantages of goal orientated approach?
In some organisations, goals change so quickly that the approach is less useful.
How can one be sure that a goal is precisely satisfied by its sub goals.
Distinguishing between leaf goals and the means to achieve them is not always clear
