![]() ![]() So, the best way to accomplish this is to create one use case (the parent) which contains the common behavior and then create two specialized child use cases which inherit from the parent and which contain the differences specific to registering on-line vs. Generalization: represents the relative difference in abstraction level between the two use cases. However, there would also be differences between the two. If you are creating a payment system which allows students of a training provider to pay for courses both on-line and by phone, there will many things in common between the two scenarios: specifying personal info, specifying payment info, etc. Within a UML-based development, the very first model to be designed is the use case diagram, that is later used all over the modeling process. related to classification) directed relationship between a more general classifier (superclass) and a more specific classifier (subclass). Complementing the use case diagram, you would typically have a use case specification describing the actual sequence of operations of each of your use cases. A use-case generalization from a more specific, or specialized, use case to a more general, or generalized, use case indicates that the more specific use case receives or inherits the actors, behavior sequences, and extension points of the more general use case, and that instances of the more specific use case may be substituted for instances. In this instance, you can describe the common parts in a separate use case (the parent) which then is specialized into two or more specialized child use cases. A generalization is a binary taxonomic (i.e. ![]() You can use the generalization relationship when you find two or more use cases which have common behavior/logic. The child use case is connected at the base of the arrow. Use generalization and specialization Another way to handle complex scenarios and exceptions is to use the generalization and specialization relationships between actors and use cases. The child use case is also referred to the more specialized use case while the parent is also referred to as the more abstract use case of the relationship.įor those of you familiar with object oriented concepts: use cases in UML are classes and the generalization is simply the inheritance relationship between two use cases by which one use case inherits all the properties and relationships of another use case. In a use case diagram, generalization is shown as a directed arrow with a triangle arrowhead. Generalization relationships are used in class, component, deployment, and use-case diagrams to indicate that the child receives all of the attributes, operations, and relationships that are defined in the parent. ![]() In the context of use case modeling the use case generalization refers to the relationship which can exist between two use cases and which shows that one use case (child) inherits the structure, behavior, and relationships of another actor (parent). A use-case-generalization is a relationship from a child use case to a parent use case, specifying how a child can specialize all behavior and characteristics. ![]()
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