![]() I use qualifiers within implementation models to show uses of a map, dictionary, associative array, or similar data structure. With the way StarUML implements the Class-owned Association-end, there is always duplicate Properties since this End (a Property) has to be linked to an Attribute (also a Property). I'm quite happy to use both this and an unqualified association at the same time if that is a suitable interface. In conceptual modeling, I use the qualifier construct only to show constraints along the lines of "single Order Line per Product on Order." In specification models, I use it to show a keyed lookup interface. In this project we are only interested in model elements. A view element refers to an icon contained in some diagram. However, it is described by additional attributes which does not belong to the objects involved in the association. It has its own name, attributes operations, just like any other ordinary class. A diagram element obviously refers to an entire UML diagram such as a class diagram, use case diagram, sequence diagram, etc. An association class, which is essentially a class attached to an association, is used to model an association as a UML class. ![]() A multiplicity of 1 would indicate that there must be a Line Item for every Product * would indicate that you can have multiple Order Lines per Product but that access to the Line Items is still indexed by Product.įrom an implementation perspective, this suggests the use of an associative array or similar data structure to hold the order lines. A model element refers to a logical UML element such as a UML package, class, association, etc. ![]() Thus, all access to a given Line Item requires a Product as an argument. From a specification perspective, this qualified association would imply an interface along the lines of The qualifier says that in connection with an Order, there may be one Order Line for each instance of Product.Ĭonceptually, this example indicates that you cannot have two Order Lines within an Order for the same Product. A qualified association is the UML equivalent of a programming concept variously known as associative arrays, maps, and dictionaries.įigure 6-13 shows a way of representing the association between the Order and Order Line classes that uses a qualifier. ![]()
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