1、1,An Introduction to UML Interaction (Sequence and Communication) Diagrams,Georgia State University CIS 3300 Spring, 2010,Models, Views, and Diagrams,Activity Diagrams,A model is a complete description of a system from a particular perspective,Models,3,Behavioral Diagrams,Used to visualize, specify,
2、 construct, document dynamic aspects of system: use case diagram sequence diagram communication diagram state machine diagram activity diagram,4,Diagramming Scenarios: UML ways of expressing scenarios,Activity diagrams Several scenarios (even a full use case) at once Similar to Petri nets, Graphcet,
3、 (concurrent) flow charts Interaction (sequence and communication) diagrams Only one scenario per diagram Involve/introduce (high level) objects Sequence diagram Accent on the time flow Communication diagram Accent on the messages between objects,5,Interaction Diagrams (Sequence and Communication),D
4、escribe how groups of objects collaborate in some behavior Sequence diagrams Time-oriented Communication diagrams Message-oriented,6,Diagramming Scenarios: Sequence Diagrams,Describe one scenario Involve objects and messages Shows a number of objects and the messages that are passed between these ob
5、jects. Accent is on the time flow of events,7,Simple scenario:,Diagramming Scenarios: Sequence Diagrams,We have an order and are going to invoke a command on it to calculate its price. To do that, the order needs to look at all the line items on the order and determine their prices, which are based
6、on the pricing rules of the orders line products. Having done that for all the line items, the order then needs to compute an overall discount, which is based on rules tied to the customer.,10,Sequence Diagrams,UML 1.0 versus UML 2.0: Objects pass messages (UML 1.0) Participants pass messages (UML 2
7、.0) Show how participants (objects) interact. Differences in interaction styles: Fig 4-1: Centralized, e.g. one participant does all the processing and other participants supply data. Fig 4-2: Distributed, e.g. processing is split among many participants.,11,Diagramming Scenarios: Sequence Diagrams
8、(cont.),12,Interaction and Message,An interaction is a behavior that comprises a set of messages, exchanged among a set of objects, to accomplish a specific purpose.A message is the specification of a communication between objects that conveys information, with the expectation that some kind of acti
9、vity will ensue.,13,Sequence Diagram,A sequence diagram is an interaction diagram that emphasizes the time ordering of messages. A lifeline is a vertical dashed line that represents the lifetime of an object. A focus of control is a tall, thin rectangle that shows the period of time during which an
10、object is performing an action.,14,Sequence Diagram Notation,15,Sequence Diagram Notation,16,Sequence Diagram Notation,17,Sequence Diagram,Captures dynamic behavior (time-oriented) Purpose Model flow of control Illustrate typical scenarios,18,UML Sequence Diagrams,Used during requirements analysis T
11、o refine use case descriptions to find additional objects (“participating objects”) Used during system design to refine subsystem interfaces Classes (and objects) are represented by columns Messages are represented by arrows Activations are represented by narrow rectangles Lifelines are represented
12、by dashed lines,selectZone(),pickupChange(),pickUpTicket(),insertCoins(),UML Sequence Diagrams: Nested Messages,The source of an arrow indicates the activation which sent the message An activation is as long as all nested activations,ZoneButton,Dataflow,to be continued.,21,Sequence Diagram Observati
13、ons,UML sequence diagram represent behavior in terms of interactions. Complement the class diagrams which represent structure. Useful to find participating objects. Time consuming to build but worth the investment.,22,Diagramming Scenarios: Communication Diagrams,Describe one scenario Involve object
14、s and messages Accent is on messages exchanged between objectsSequence and Communication diagrams are largely equivalent.,23,Diagramming Scenarios: Communication Diagrams (cont.),24,Communication Diagram,A communication diagram is an interaction diagram that emphasizes the organization of the object
15、s that participate in the interaction. A path is a link between objects, perhaps with a stereotype such as local attached. Sequence numbers indicate the time ordering of messages, to one or more levels.,25,Communication Diagram,Captures dynamic behavior (message-oriented) Purpose Model flow of control Illustrate coordination of object structure and control,26,Communication Diagram Notation,27,Communication Diagram Notation,28,
