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An Overview of UML Diagrams


codeling 1573 - 6555
@2019-04-10 14:09:23

Understanding the UML diagrams is an important part of understanding and performing object-oriented analysis and design in software development.

UML, short for Unified Modeling Language, is a standardized modeling language consisting of an integrated set of diagrams, developed to help system and software developers for specifying, visualizing, constructing, and documenting the artifacts of software systems. The UML uses mostly graphical notations to express the design of software projects.

There are three classifications of UML diagrams:

  • Structure diagrams. A type of diagram that depicts the elements of a specification that are irrespective of time. This includes class, composite structure, component, deployment, object, and package diagrams.
  • Behavior diagrams. A type of diagram that depicts behavioral features of a system or business process. This includes activity, state machine, and use case diagrams as well as the four interaction diagrams.
  • Interaction diagrams. A subset of behavior diagrams which emphasize object interactions. This includes communication, interaction overview, sequence, and timing diagrams.

UML Diagram Types 




Activity Diagram

Depicts high-level business processes, including data flow, or to model the logic of complex logic within a system.

Class Diagram

Shows a collection of static model elements such as classes and types, their contents, and their relationships.

Communication Diagram

Shows instances of classes, their interrelationships, and the message flow between them. Communication diagrams typically focus on the structural organization of objects that send and receive messages. Formerly called a Collaboration Diagram.

Component Diagram

Depicts the components that compose an application, system, or enterprise. The components, their interrelationships, interactions, and their public interfaces are depicted.

Composite Structure Diagram

Depicts the internal structure of a classifier (such as a class, component, or use case), including the interaction points of the classifier to other parts of the system.

Deployment Diagram

Shows the execution architecture of systems. This includes nodes, either hardware or software execution environments, as well as the middleware connecting them.

Interaction Overview Diagram

A variant of an activity diagram which overviews the control flow within a system or business process. Each node/activity within the diagram can represent another interaction diagram.

Object Diagram

Depicts objects and their relationships at a point in time, typically a special case of either a class diagram or a communication diagram.

Package Diagram

Shows how model elements are organized into packages as well as the dependencies between packages.

Sequence Diagram

Models the sequential logic, in effect the time ordering of messages between classifiers.

State Machine Diagram

Describes the states an object or interaction may be in, as well as the transitions between states. Formerly referred to as a state diagram, state chart diagram, or a state-transition diagram.

Timing Diagram

Depicts the change in state or condition of a classifier instance or role over time. Typically used to show the change in state of an object over time in response to external events.

Use Case Diagram

Shows use cases, actors, and their interrelationships.

@2019-04-11 13:34:10

In Visual Studio, a component diagram shows the parts of a design for a software system. A component diagram helps you visualize the high-level structure of the system and the service behavior that those pieces provide and consume through interfaces. To create a UML component diagram, on the Architecture menu, click New UML or Layer Diagram.

The following table describes the elements that you can use on a component diagram, together with their main properties.

Elements used on component diagrams

Shape Element Description and Main Properties
1 Component A reusable piece of system functionality. A component provides and consumes behavior through interfaces, and can use other components.

You can hide or show the internal parts of a component using the expand/collapse control (9).

A component is a kind of class.

- Is Indirectly Instantiated. If true (default), the component exists only as a design artifact. At run time, only its parts exist.
2 Provided Interface Port Represents a group messages or calls that a component implements and that other components or external systems can use. A port is a property of a component that has an interface as its type.
3 Required Interface Port Represents a group of messages or calls that the component sends to other components or external systems. The component is designed to be coupled to components that provide at least these operations. The port has an interface as its type.
4 Dependency Can be used to indicate that a Required Interface on one component can be satisfied by a Provided Interface on another.

Dependencies can also be used more generally between model elements, to show that the design of one depends on the design of the other.
5 Part An attribute of a component, whose type is a usually another component. A part is used in the internal design of its parent component. Parts are shown graphically, nested within the parent component.

To create a Part of an existing component type, drag the component from UML Model Explorer onto the owner component.

To create a Part of a new type, click the Component tool and then click the owner component.

For example, a component Car has parts engine:CarEngine, backLeft:Wheel, frontRight:Wheel, and so on.

More than one part can have the same type, and different components can have parts of the same type.

- Type. The type of the part, which is defined elsewhere in the model. Typically, the type is another component.
- Multiplicity. Defaults to 1. You can set it to 0..1 to indicate that the part can have the value null, \* to indicate that the part is a collection of instances of the given type, or to any expression that can be evaluated to a range of numbers.
6 Part Assembly A connection between the required interface ports of one part and the provided interface ports of another. The implementation of a part assembly can vary from one component to another. The connected parts must have the same parent component.
7 Delegation Links a port to an interface of one of the component's parts. Indicates that messages sent to the component are dealt with by the part, or that messages sent from the part are sent out from the parent component.
(not shown) Generalization Indicates that one component inherits from another component. Parts and interfaces are inherited.
9 Collapse/Expand control Use this to hide or show a component's internal parts.
(not shown) Comment For additional notes. You can link a comment to any number of elements on the diagram by using the Connector tool.


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