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A stereotype is one of three types of extensibility mechanisms in the Unified Modeling Language (UML), the other two being tags and constraints. [1]: 73 They allow designers to extend the vocabulary of UML in order to create new model elements, derived from existing ones, but that have specific properties that are suitable for a particular domain or otherwise specialized usage.
Object-oriented applications contain complex webs of interrelated objects. Objects are linked to each other by one object either owning or containing another object or holding a reference to another object. This web of objects is called an object graph and it is the more abstract structure that can be used in discussing an application's state.
"An object diagram is a graph of instances, including objects and data values. A static object diagram is an instance of a class diagram; it shows a snapshot of the detailed state of a system at a point in time. The use of object diagrams is fairly limited, namely to show examples of data structure."
The indirection pattern supports low coupling and reuses potential between two elements by assigning the responsibility of mediation between them to an intermediate object. An example of this is the introduction of a controller component for mediation between data (model) and its representation (view) in the model-view-controller pattern.
UML diagrams used to represent the physical view include the deployment diagram. [2] Scenarios: The description of an architecture is illustrated using a small set of use cases, or scenarios, which become a fifth view. The scenarios describe sequences of interactions between objects and between processes.
The object collaboration diagram shows the run-time interactions: In this example, the Client object sends a request to the top-level Composite object (of type Component) in the tree structure. The request is forwarded to (performed on) all child Component objects (Leaf and Composite objects) downwards the tree structure.
Ports can optionally specify the services they provide and the services they require from other parts of the system. In the diagram, each of the small squares is a port. Each port has a type and is labelled with a name, such as "var", "indVar1", or "view" in the diagram. Ports may contain a multiplicity factor, for example [3].
Most problematic from a software design point of view is the tight coupling of the mutually dependent modules which reduces or makes impossible the separate re-use of a single module. Circular dependencies can cause a domino effect when a small local change in one module spreads into other modules and has unwanted global effects (program errors ...