TIMe - Tutorial on UML
Suggested reading: Practical UML: A hands on introduction for developers sequence diagrams. –. . relationships, such as drawing the Object class. Aggregation, Represents “is part of” or “contains” relationships between two classes or . UML sequence diagrams are a dynamic modeling technique, as are. Relationships between UML Sequence Diagrams and the Topological Functioning Model for Backward. Transformation. Viktoria Ovchinnikova1, Erika Asnina2.
Messages are shown as arrows. They can be complete, lost or found; synchronous or asynchronous; call or signal. Activate is used to denote participant activation. Once a participant is activated, its lifeline appears.
Objects are model elements that represent instances of a class or of classes. Classes in UML show architecture and features of the designed system. Actor specifies a role played by a user or any other system that interacts with the subject. It is used to model how activities are coordinated to provide a service; to show the events needed to achieve some operation, and to illustrate how the events in a single use case relate to one another.
Usage Activity diagrams consist of activities, states and transitions between activities and states. The initial state is the starting point on the activity diagram. It is the point at which you begin reading the action sequence. An activity is a unit of work that needs to be carried out. State defines current condition of an event or activity. Decision activity is introduced in UML to support conditionals in activities. It shows where the exit transition from a state or activity may branch in alternative directions depending on a condition.
The bar represents synchronization of the completion of those activities. Control flow in computer science refers to the order in which the individual statements, instructions or function calls of an imperative or a declarative program are executed or evaluated.
Different UML Diagrams - Purpose and Usage
An object flow is the same thing as a control flow, but it is shown as a dashed line instead of a solid one. Activity Diagram UML Collaboration Diagram Purpose A collaboration diagram is used to describe a collection of objects that interact to implement some behavior within a context.
It's used to model system functionality, which in specific, visualize the relationship between objects collaborating to perform a particular task and model the logic of the implementation for a complex operation. Usage Collaboration diagram is also called communication diagram or interaction diagram. It consists of object, multi-object, actor, association role, delegation, link to self, constraint and note. Multi-object represents a set of lifeline instances.
Link-to-self is used to link a message which can be sent from an object to itself. Collaboration Diagram UML Class Diagram Purpose A UML class diagram is not only used to describe the object and information structures in an application, but also show the communication with its users.
It provides a wide range of usages; from modeling the static view of an application to describing responsibilities for a system. Composition is a special type of aggregation that denotes a strong ownership.
Usage In a UML class diagram, classes represent an abstraction of entities with common characteristics. Associations represent static relationships between classes. The scope is the class itself.
Different UML Diagrams - Purpose and Usage
Otherwise, instance scope is assumed by default. Relationships[ edit ] UML relations notation A relationship is a general term covering the specific types of logical connections found on class and object diagrams.
UML defines the following relationships: Dependency[ edit ] A dependency is a semantic connection between dependent and independent model elements. This association is uni-directional. Association[ edit ] Class diagram example of association between two classes An association represents a family of links. A binary association with two ends is normally represented as a line. An association can link any number of classes. An association with three links is called a ternary association.
An association can be named, and the ends of an association can be adorned with role names, ownership indicators, multiplicity, visibility, and other properties. There are four different types of association: Bi-directional and uni-directional associations are the most common ones.
For instance, a flight class is associated with a plane class bi-directionally. Association represents the static relationship shared among the objects of two classes. Aggregation[ edit ] Class diagram showing Aggregation between two classes. Here, a Professor 'has a' class to teach. Aggregation is a variant of the "has a" association relationship; aggregation is more specific than association.
Class diagram - Wikipedia
It is an association that represents a part-whole or part-of relationship. As shown in the image, a Professor 'has a' class to teach. As a type of association, an aggregation can be named and have the same adornments that an association can. However, an aggregation may not involve more than two classes; it must be a binary association.
Furthermore, there is hardly a difference between aggregations and associations during implementation, and the diagram may skip aggregation relations altogether. The contents of the container still exist when the container is destroyed. In UMLit is graphically represented as a hollow diamond shape on the containing class with a single line that connects it to the contained class.
The aggregate is semantically an extended object that is treated as a unit in many operations, although physically it is made of several lesser objects. Here the student can exist without library, the relation between student and library is aggregation. Composition[ edit ] Two class diagrams.
The diagram on top shows Composition between two classes: A Car has exactly one Carburetor, and a Carburetor has at most one Car Carburetors may exist as separate parts, detached from a specific car. The diagram on bottom shows Aggregation between two classes: A Pond has zero or more Ducks, and a Duck has at most one Pond at a time.