P (Glossary) [EA User Guide]

~P~

package

1.	A namespace, as well as an element that can be contained in other packages' namespaces. Packages can own or merge with other packages, and their elements can be imported into a package's namespace.

2.	A logical container of model elements. It groups elements and can also contain other packages.

The OMG UML specifications states:

'A package is a grouping of model elements. Packages themselves may be nested within other packages. A package may contain subordinate packages as well as other kinds of model elements. All kinds of UML model elements can be organized into packages.'

Note that packages own model elements and are the basis for configuration control, storage and access control. Each element can be directly owned by a single package, so the package hierarchy is a strict tree. However, packages can reference other packages, modeled by using one of the stereotypes «import» and «access» of Permission dependency, so the usage network is a graph. Other kinds of dependencies between packages usually imply that one or more dependencies among the elements exist.

A package is shown as a large rectangle with a small rectangle (a 'tab') attached to the left side of the top of the large rectangle. It is the common folder icon.

package diagram

Used to reflect the organization of packages and their elements, and provide a visualization of their corresponding namespaces.

package import

A package import relationship is drawn from a source package to a package whose contents are imported. Private members of a target package cannot be imported.

package merge

Indicates a relationship between two packages whereby the contents of the target package are merged with those of the source package. Private contents of a target package are not merged.

parameter

The specification of a variable that can be changed, passed, or returned. A parameter can include a name, type, and direction. Parameters are used for operations, messages, and events.

Synonym: formal parameter

Contrast: argument

parameterized element

The descriptor for a class with one or more unbound parameters.

Synonym: template, parameterized class

parent

In a generalization relationship, the generalization of another element, the child.

See also: subclass, subtype

Contrast: child

part

A run-time instance of a class or interface.

participate

The connection of a model element to a relationship or to a reified relationship. For example, a class participates in an association, an actor participates in a use case.

partition

1.	activity graphs: A portion of an activity graph that organizes the responsibilities for actions. See also: swim lane

2.	architecture: A set of related classifiers or packages at the same level of abstraction or across layers in a layered architecture. A partition represents a vertical slice through an architecture, whereas a layer represents a horizontal slice.

Contrast: layer

pattern

A template collaboration.

persistent object

An object that exists after the process or thread that created it has ceased to exist.

physical system

1.	The subject of a model.

2.	A collection of connected physical units, which can include software, hardware and people, that are organized to accomplish a specific purpose. A physical system can be described by one or more models, possibly from different viewpoints.

Contrast: system

port

Defines the interaction between a classifier and its environment. Interfaces controlling this interaction can be depicted using the 'Expose Interface' Toolbox Icon.

postcondition

A constraint that must be true at the completion of an operation.

precondition

A constraint that must be true when an operation is invoked.

primitive type

A pre-defined basic datatype without any substructure, such as an integer or a string.

process

1.	A heavyweight unit of concurrency and execution in an operating system. Contrast: thread, which includes heavyweight and lightweight processes. If necessary, an implementation distinction can be made using stereotypes.

2.	A software development process - the steps and guidelines by which to develop a system.

3.	To execute an algorithm or otherwise handle something dynamically

profile

A stereotyped package that contains model elements that have been customized for a specific domain or purpose using extension mechanisms, such as stereotypes, tagged definitions and constraints. A profile can also specify model libraries on which it depends and the metamodel subset that it extends.

Project Browser window

The workspace window (top left) where the model contents are displayed in 'tree' format. Displays structures such as packages, diagrams and model elements.

projection

A mapping from a set to a subset of it.

property

A named value denoting a characteristic of an element. A property has semantic impact. Certain properties are predefined in the UML; others can be user defined.