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Attributes and Constraints

Q: What method constraints are there?

Generated because derived from EDG and FSM - Referential Integrity: end master & create dependent with cardinality 1 - Sequence: e.g. Are derived pre-conditions from the transition table

Q: What are multiple propagation constraints?

Nest--Marsu--Jungle--Country--Continent Constraints in class NEST - marsu mother & father are different - mother & father should be from same jungle: thus same country & continent - mother & father should be from same country: thus same continent - mother & father should be from same continent - mother & father can be from anywhere: no constraint

Q: What are multiple propagation rules?

Happens when we have 2 paths from a dependant to one master. 3 customers are involved in 1 invoice line: One of delivery, order & invoice. Do you invoice to same customer as the one who placed the order? YES = MP constraint NO = use Alias MP constraint: self.medicine.category = self.prescription.medicine.category Alias: medicine is under category: fever medicine

Q: What are recursive associations constraints?

Person -- Team relationship A person should not be twice in the same team A person should not be his/her own supervisor Supervisor should not be supervised by someone in their team --> has to be looked through recursively Either through constraints or aliasses: Use aliasses when: different preconditions and method body

6 important questions on Attributes and Constraints

What defines class & method constraints?

Class constraints = invariants, must be satisfied at any time, by all instances in the class

Methods constraints = pre and post-conditions per method, to be satisfied before invocation of the method, only by the instance on which operation is invoked

What class constraints are there

Uniqueness constraints
- usesful for identifying keys for DB design)
- e.g. Class ORDER, unique{....}

Attribute Constraints:
- domain specific
- Class MEMBER, count(ref_loan)<=5

What method constraints are there?

Generated because derived from EDG and FSM
- Referential Integrity: end master & create dependent with cardinality 1
- Sequence: e.g. Are derived pre-conditions from the transition table

What are multiple propagation constraints?

Nest--Marsu--Jungle--Country--Continent

Constraints in class NEST
- marsu mother & father are different
- mother & father should be from same jungle: thus same country & continent
- mother & father should be from same country: thus same continent
- mother & father should be from same continent
- mother & father can be from anywhere: no constraint

What are multiple propagation rules?

Happens when we have 2 paths from a dependant to one master.

3 customers are involved in 1 invoice line: One of delivery, order & invoice. Do you invoice to same customer as the one who placed the order?
YES = MP constraint
NO = use Alias

MP constraint: self.medicine.category = self.prescription.medicine.category
Alias: medicine is under category: fever medicine

What are recursive associations constraints?

Person -- Team relationship

A person should not be twice in the same team
A person should not be his/her own supervisor
Supervisor should not be supervised by someone in their team --> has to be looked through recursively

Either through constraints or aliasses: Use aliasses when: different preconditions and method body

The question on the page originate from the summary of the following study material:

Architecture and Modelling of Management Information Systems

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