Behavior in the Application Layer is described in a way that is very similar to Business Layer behavior. Also here, a distinction is made between the external behavior of application components in terms of application services, and the internal behavior of these components; i.e., application functions that realize these services.
Application Function is a behavior element that groups automated behavior that can be performed by an application component.
In the model below, the internal behavior of the Financial application component is modeled as an application function consisting of two sub-functions. These application functions realize the application services that are made available to the users of the application.
Application Function realises Application Service(s)
Other Application Services or Functions used by Application Functions and Infrastructure Services
Application Function accesses Data Object
Application Component assigned to Application Function
Application Interaction is a behavior element that describes the behavior of application collaboration. The Application Interaction provides the general behavioral detail that lies behind a collaboration. A UML Sequence Diagram is useful to model the detail. Name using a verb.
In the model below, an Accounting component and a Billing component of a financial system cooperate to compose an administrate transactions interaction. This is modeled as an application interaction assigned to the collaboration between the two components.
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Application Collaboration assigned to Application Interaction
Application Interaction realizes an Application Service
Application Services and Infrastructure Services used by Application Interaction
Application Interaction accesses Data Object
Application Service is a service that exposes automated behavior. The Application Service in effect is providing some informational service needed by the business. It is these Services, for instance, that could be “orchestrated” to underpin a business process. It represents what you actually get from the Application Component.
In the model below, an application event Request for a Quotation triggers an application process "Obtain Travel Insurance", which is served by the two aforementioned application services.
Application Service used by Business Processes, Functions, Interactions or Application Functions
Application Function realises Application Service
Application Interface assigned to Application Service
Application Service accesses Data Object