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4.1 UML 2.0 Components
"A component is a self contained unit that encapsulates the state and behavior of a number of classifiers. A
component specifies a formal contract of the services that it provides to its clients and those that it requires from
other components or services in the system in terms of its provided and required interfaces.
A component is a substitutable unit that can be replaced at design time or run-time by a component that offers
that offers equivalent functionality based on compatibility of its interfaces"
The graphical notation for a UML 2.0 Component is either a "black box" view to only show the interfaces, or a
"white box" view to show the internal assembly of subcomponents if any (parts or classifiers). The component
logo can be associated or replace the <<component>> keyword.
4.2 UML 2.0 Interfaces
"An interface declares a set of public features and obligations that constitute a coherent service offered by a
classifier. Interfaces provide a way to partition and characterize groups of properties that realizing classifier
instances must possess. An interface does not specify how it is to be implemented, but merely what needs to be
supported by realizing instances. That is, such instances must provide a a public facade (attributes, operations,
externally observable behavior) that conforms to the interface."
using the AADL for mission critical software development page 5
<<component>>
name
expanded UML 2.0 interfaces
<<interface>>
provided
attribute1
attribute2
operation1
operaion2
<<interface>>
required
attribute3
attribute4
operation3
operaion4
name
<<component>>
:name1
provided
interface
required
interface
connectors in a UML 2.0 component
<<component>>
:name2
"The set of interfaces realized by a classifier are its provided interfaces, which represent the obligations that
instances of that classifier have to their clients. They describe the services that the instances of that classifier
offer to their clients. Interfaces may also be used to specify required interfaces, which are specified by a usage
dependency between the classifier and the corresponding interfaces. Required interfaces specify services that a
classifier needs in order to perform its function and fulfill its own obligations to its clients."
Interfaces can be represented with the compact "ball-socket" graphical notation, or expanded as classes, with
operations and attributes:
4.3 UML 2.0 Connectors
Like the other compositional notations, UML 2.0 specifies two main kinds of connectors between components:
the links between components that are as the same level, and the links between a container component and its
parts:
"A delegation connector is a declaration that behavior that is available on a component instance is not actually
realized by that component itself, but by another instance that has “compatible” capabilities. This may be
another Component or a (simple) Class."
"An assembly connector is a connector between two components that defines that one component provides the
services that another component requires. An assembly connector is a connector that is defined from a required
interface or port to a provided interface or port."
To comply with the HOOD method, the assembly connector can be mapped to the Use relationship between
sibling components, the (required) delegation connector can be used to describe the Use relationship between a
component and its environment outside its immediate parent, and the (provided) delegation connector can be
used to represent the Implemented_By relationship. However, unlike with HOOD or the AADL, the delegation
connectors only links two interfaces, and doesn't provide the details of the individual links between each
features.
delegate
"provided"
delegate
"required"
assembly
using the AADL for mission critical software development page 6
5 All together: Stood v5
Stood is the HOOD tool that is in use for many mission critical projects such as the Airbus A380 embedded
software. The last release of the product now includes an AADL interchange feature and a UML 2.0 structure
diagrams editor, together with the HOOD notation. All the existing processing features such as design rules
checkers, code generators and reverse engineering, and documentation generators remain available.
This was made possible by the various connections that was defined between these three modeling techniques.
Each of them brings its specific benefits: AADL offers a powerful and precise semantics for real-time
　
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