Organization of objects in a system taking part in the message flow.įollowing things are to be identified clearly before drawing the interaction diagram The message flow from one object to another and the collaboration diagram describes the The sequence diagram captures the time sequence of We have two types of interaction diagrams in UML. Snapshot of the running system at a particular moment So to capture the dynamic aspect, we need to understand what a dynamic aspect is and how it is visualized. To describe the interaction among objects.Īs we have already discussed, the purpose of interaction diagrams is to capture the dynamic aspect of a system. To describe the structural organization of the objects. To describe the message flow in the system. To capture the dynamic behaviour of a system. Sequence and collaboration diagrams are used to capture the dynamic nature but from a different angle. Hence, the solution is to use different types of models to capture the different aspects of the interaction. Visualizing the interaction is a difficult task. The purpose of interaction diagrams is to visualize the interactive behavior of the system. Sequence diagram emphasizes on time sequence of messages and collaboration diagram emphasizes on the structural organization of the objects that send and receive messages. The basic purpose of both the diagrams are similar. This interactive behavior is represented in UML by two diagrams known as Sequence diagram and Collaboration diagram. This interaction is a part of dynamic behavior of the system. The example "Design elements - UML sequence diagrams" is included in the Rapid UML solution from the Software Development area of ConceptDraw Solution Park.From the term Interaction, it is clear that the diagram is used to describe some type of interactions among the different elements in the model. It should be the result of a message, either from the object itself, or another.Ī message sent from outside the diagram can be represented by a message originating from a filled-in circle (found message in UML) or from a border of the sequence diagram (gate in UML)." When an object is destroyed (removed from memory), an X is drawn on top of the lifeline, and the dashed line ceases to be drawn below it (this is not the case in the first example though). Objects calling methods on themselves use messages and add new activation boxes on top of any others to indicate a further level of processing. Activation boxes, or method-call boxes, are opaque rectangles drawn on top of lifelines to represent that processes are being performed in response to the message (ExecutionSpecifications in UML). Asynchronous calls are present in multithreaded applications and in message-oriented middleware. If a caller sends an asynchronous message, it can continue processing and doesn’t have to wait for a response. If a caller sends a synchronous message, it must wait until the message is done, such as invoking a subroutine. Solid arrow heads represent synchronous calls, open arrow heads represent asynchronous messages, and dashed lines represent reply messages. Messages, written with horizontal arrows with the message name written above them, display interaction. Note that leaving the instance name blank can represent anonymous and unnamed instances. If the lifeline is that of an object, it demonstrates a role. The vector stencils library "UML sequence diagrams" contains 50 symbols for the ConceptDraw PRO diagramming and vector drawing software.
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