Component and Composite Structure Diagrams

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Component and Composite Structure Diagrams

• Keng Siau
• University of Nebraska-Lincoln

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Component and Composite Structure Diagrams

• A component diagram shows the internal parts,
  connectors, and ports that implement a component
• A composite structure diagram shows the internal
  structure of a class or a collaboration
• The difference between component and composite
  structure is small and we will treat them both as
  component diagrams

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Terms and Concepts

• An interface is a collection of operations that
  specify a service that is provided by or
  requested from a class or component
• A component is a replaceable part of a system
  that conforms to and provides the realization of
  a set of interfaces
• A port is a specific window into an encapsulated
  component accepting messages to and from the
  component conforming to specified interfaces

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Terms and Concepts (cont)

• Internal structure is the implementation of a
  component by means of a set of parts that are
  connected together in a specific way
• A part is the specification of a role that
  composes part of the implementation of a
  component.
• In an instance of the component, there is an
  instance corresponding to the part
• A connector is a communication relationship
  between two parts or ports within the context of
  a component

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Components

• A component is a replaceable part of a system
  that conforms to and provides the realization of
  a set of interfaces
• Graphically, a component is rendered as a
  rectangle with a small two-pronged icon in its
  upper right corner

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Components and Interfaces

• An interface is a collection of operations that
  are used to specify a service of a class or a
  component
• An interface that a component realizes is called
  a provided interface
• An interface that the component provides as a
  service to other components

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Components and Interfaces

• An interface that a component uses is called a
  required interface
• An interface that the component conforms to when
  requesting services from other components
• A given interface may be provided by one
  component and required by another
• A component that uses a given interface will
  function properly no matter what component
  realizes that interface

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Components and Interfaces
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Binary Replaceability

• The basic intent of every component-based
  operating system facility is to permit the
  assembly of systems from binary replaceable parts
• Can create a system out of components and then
  evolve that system by adding new components and
  replacing old ones

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Characteristics of A Component

• It is replaceable
• It is part of a system
• It conforms to and provides the realization of a
  set of interfaces
• Component diagrams can be used for both logical
  and physical modeling
• Component diagrams are often used for physical
  modeling of the software architectures of systems
  

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Organizing Components

• Can organize components by grouping them in
  packages in the same manner in which one
  organizes classes
• Can organize components by specifying dependency,
  generalization, association (including
  aggregation), and realization relationship among
  them

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Ports

• A port is an explicit window into an encapsulated
  component
• A port has identity
• Ports permit the interfaces of a component to be
  divided into discrete packets and used
  independently
• A port is shown as a small square straddling the
  border of a component
• It represents a hole through the encapsulation
  boundary of the component

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Ports (cont)

• Both provided and required interfaces may be
  attached to a port
• A provided interface represents a service that
  can be requested through that port
• A required interface represents a service that
  the port needs to obtain from some other
  component
• Each port has a name so that it can be uniquely
  identified given the component and the port name
• Ports are part of a component

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Ports
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Internal Structure

• The internal structure of a component is the
  parts that compose the implementation of the
  component together with the connections among
  them
• A part is a unit of the implementation of a
  component
• A part has a name and a type

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Parts within A Component
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Parts of the Same Type
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Connector

• A wire between two ports is called a connector
• Show connectors in two ways
• If two components are wired explicitly, draw a
  line between them or their ports
• If two components are connected because they have
  compatible interfaces, use a ball-and-socket
  notation
• A delegation connector wires internal ports to
  external ports of the overall component

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Connectors
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Component Diagrams

• A component diagram shows an encapsulated class
  and its interfaces, ports, and internal structure
  consisting of nested components and connectors
• Component diagrams address the static design
  implementation view of a system

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Example of Component Diagram