Define the associate you made between the Diary and Reservation class.
Most of the interesting information about an association is attached at its ends. (The association end is part of the association, not part of the class.) An association between two classes contains two association ends. A joint association between three classes (referred to as a ternary association) contains three association ends, and so on.
1 Open the definition dialog of the association Maintains between Reservation and Diary.
The definition of an association contains a grid of the class roles that the association is involved in. Each row in the grid represents an Association End.
Role Names
The name of the association end is the name of the Role played by that the class for that end. For example, if you had an association Married between the class Man and the class Woman, the role name on the Man side would be Husband and the role name on the Woman side would be Wife. Naming the association end is optional; the name appears on the association at the end of the class it specifies.
1 Click in the Name cell for the Diary class and type in Maintainer–this is the role that the Diary class plays in this association.
2 Click in the Name cell for the Reservation class and type in Maintainee –this is the role that the Reservation class plays in this association.
Specifying Multiplicity
A single Diary maintains zero or more Reservations (zero because it might be possible that at a point in time there are no reservations, although this is unlikely). These numbers are considered the multiplicity of the association.
1 Click in the Multiplicity grid for Diary, and select Only One from the list. Select Zero, One or Many as the multiplicity for the Reservation side of the association.
Specifying a Qualifier
A qualifier narrows down the multiplicity of an association. For example, the relationship between classes Diary and Reservation has a multiplicity of one-to-zero-or-more, in other words, one Diary maintains many Reservations. The addition of a qualifier such as Reservation_Number reduces the multiplicity to one-to-one, in other words, a Diary maintains one Reservation_Number.
1 Click in the Maintainee Name cell of the Reservation association end, and click Define at the bottom of the grid to open the Association End's full definition dialog.
2 Click the Qualifier tab.
3 Type in Reservation_Number in the Qualifier - (Class Attribute) list.
4 Press Add to add the Qualifier to the list.
5 Click OK to close the Association End definition dialog.
6 Click OK to close the Association definition dialog.
Notice that on the diagram, the qualifier appears in a box attached to the Reservation class. You can adjust the positioning of the association name, the role names, and the multiplicities. Notice that System Architect prevents you from moving the role name and multiplicity to the side of the other class; it can only reside on the side of the class it represents.
