A class that provides common behavior across a set of subclasses but is not itself designed to have instances. An abstract class represents a concept; classes derived from it represent implementations of the concept. See also: base class. Contrast: concrete class.

The essential characteristics of an entity that distinguish it from all other kinds of entities. An abstraction defines a boundary relative to the perspective of the viewer.

The specification of an executable statement that forms an abstraction of a computational procedure. An action typically results in a change in the state of the system, and can be realized by sending a message to an object or modifying a link or a value of an attribute.

An expression that resolves to a sequence of actions.

A state that represents the execution of an atomic action, typically the invocation of an operation.

The execution of an action.

A class whose instances are active objects. See: active object.

An object that owns a thread and can initiate control activity. An instance of active class.

A special case of a state machine that is used to model processes involving one or more classifiers. Contrast: statechart diagram . Synonym: activity diagram.

A coherent set of roles that users of use cases play when interacting with these use cases. An actor has one role for each use case with which it communicates.

Synonym: argument.

A class that represents the "whole" in an aggregation (whole-part) relationship. See: aggregation.

A special form of association that specifies a whole-part relationship between the aggregate (whole) and a component part. See: composition.

"[...] groups of concepts that represent a common construction in business modeling. It may be relevant to only one domain, or it may span many domains."

Refers to something that occurs during an analysis phase of the software development process. See: design time, modeling time.

"An architectural pattern expresses a fundamental structural organization schema for software systems. It provides a set of predefined subsystems, specifies their responsibilities, and includes rules and guidelines for organizing the relationships between them."

The organizational structure of a system. An architecture can be recursively decomposed into parts that interact through interfaces, relationships that connect parts, and constraints for assembling parts. Parts that interact through interfaces include classes, components and subsystems.

A binding for a parameter that resolves to a run-time instance. Synonym: actual parameter. Contrast: parameter.

A physical piece of information that is used or produced by a software development process. Examples of Artifacts include models, source files, scripts, and binary executable files. An artifact may constitute the implementation of a deployable component. Synonym: product. Contrast: component.

The semantic relationship between two or more classifiers that specifies connections among their instances.

A model element that has both association and class properties. An association class can be seen as an association that also has class properties, or as a class that also has association properties.

The endpoint of an association, which connects the association to a classifier.

A request where the sending object does not pause to wait for results. Contrast: synchronous action.

A feature within a classifier that describes a range of values that instances of the classifier may hold.

The observable effects of an operation or event, including its results.

A dynamic feature of a model element , such as an operation or method .

A model aspect that emphasizes the behavior of the instances in a system, including their methods , collaborations , and state histories.

An association between two classes . A special case of an n-ary association .

The creation of a model element from a template by supplying arguments for the parameters of the template.

An enumeration whose values are true and false.

An expression that evaluates to a boolean value.

An action state that invokes an operation on a classifier .

The number of elements in a set. Contrast: multiplicity .

In a generalization relationship, the specialization of another element, the parent. See: subclass, subtype. Contrast: parent.

A description of a set of objects that share the same attributes, operations, methods, relationships, and semantics. A class may use a set of interfaces to specify collections of operations it provides to its environment. See: interface.

A diagram that shows a collection of declarative (static) model elements, such as classes, types, and their contents and relationships.

A mechanism that describes behavioral and structural features. Classifiers include interfaces, classes, datatypes, and components.

A classifier that requests a service from another classifier. Contrast: supplier.

The specification of how an operation or classifier, such as a use case, is realized by a set of classifiers and associations playing specific roles used in a specific way. The collaboration defines an interaction. See: interaction.

An annotation attached to an element or a collection of elements. A note has no semantics. Contrast: constraint.

In a deployment diagram an association between nodes that implies a communication. See: deployment diagram.

A diagram that shows interactions organized around the structure of a model, using either classifiers and associations or instances and links. Unlike a sequence diagram, a communication diagram shows the relationships among the instances. Sequence diagrams and communication diagrams express similar information, but show it in different ways. See: sequence diagram.

Refers to something that occurs during the compilation of a software module. See: modeling time, run time.

A modular, deployable, and replaceable part of a system that encapsulates implementation and exposes a set of interfaces. A component is typically specified by one or more classifiers (e.g., implementation classes) that reside on it, and may be implemented by one or more artifacts (e.g., binary, executable, or script files). Contrast: artifact.

A diagram that shows the organizations and dependencies among components.

A class that is related to one or more classes by a composition relationship. See: composition.

Synonym: composition.

A state that consists of either concurrent (orthogonal) substates or sequential (disjoint) substates. See: substate.

A substate that can be held simultaneously with other substates contained in the same composite state. See: composite state. Synonym: region.

A form of aggregation association with strong ownership and coincident lifetime as part of the whole. Parts with non-fixed multiplicity may be created after the composite itself, but once created they live and die with it; that is, they share lifetimes. Such parts can also be explicitly removed before the death of the composite. Composition may be recursive. See also: composite aggregation.

"A computation independent model is a view of a system from the computation independent viewpoint. A CIM does not show details of the structure of systems. A CIM is sometimes called a domain model and a vocabulary that is familiar to the practitioners of the domain in question is used in its specification."

A class that can be directly instantiated. Contrast: abstract class.

The occurrence of two or more activities during the same time interval. Concurrency can be achieved by interleaving or simultaneously executing two or more threads. See: thread.

A substate that can be held simultaneously with other substates contained in the same composite state. See: composite substate. Contrast: disjoint substate.

A semantic condition or restriction. Certain constraints are predefined in the UML, others may be user defined. Constraints are one of three extensibility mechanisms in UML. See: tagged value, stereotype.

(1) An instance that exists to contain other instances, and that provides operations to access or iterate over its contents; for example, arrays, lists, sets.

A namespace hierarchy consisting of model elements , and the containment relationships that exist between them. A containment hierarchy forms an acyclic graph.

A view of a set of related modeling elements for a particular purpose, such as specifying an operation .

A descriptor of a set of values that lack identity and whose operations do not have side effects. Datatypes include primitive predefined types and user-definable types. Predefined types include numbers, string and time. User-definable types include enumerations.

The model on which a repository is based. Any number of repositories can have the same defining model.

The ability of an object to issue a message to another object in response to a message. Delegation can be used as an alternative to inheritance. Contrast: inheritance .

A relationship between two modeling elements , in which a change to one modeling element (the independent element) will affect the other modeling element (the dependent element).

A diagram that shows the configuration of run-time processing nodes and the components , processes , and objects that live on them. Components represent run-time manifestations of code units. See also: component diagram .

A set of objects or components that are allocated to a process or a processor as a group. A distribution unit can be represented by a run-time composite or an aggregate .

A model element that can be computed from another element, but that is shown for clarity or that is included for design purposes even though it adds no semantic information.

The part of the software development process whose primary purpose is to decide how the system will be implemented. During design, strategic and tactical decisions are made to meet the required functional and quality requirements of a system. See: analysis .

"A design pattern provides a scheme for refining the subsystems or components of a software system, or the relationships between them. It describes a commonly-recurring structure of communicating components that solves a general design problem within a particular context."

Refers to something that occurs during a design phase of the software development process. See: modeling time . Contrast: analysis time .

A set of partially ordered steps performed for a given purpose during software development, such as constructing models or implementing models.

A graphical presentation of a collection of model elements , most often rendered as a connected graph of arcs (relationships) and vertices (other model elements). UML supports the following diagrams: class diagram , object diagram , use-case diagram , sequence diagram , communication diagram , statechart diagram , activity diagram , component diagram , and deployment diagram .

A substate that cannot be held simultaneously with other substates contained in the same composite state. See: composite state . Contrast: concurrent substate .

An area of knowledge or activity characterized by a set of concepts and terminology understood by practitioners in that area.

A semantic variation of generalization in which an object may change type or role . Contrast: static classification .

"A measure of the value of work performed so far. Earned value uses original estimates and progress-to-date to show whether the actual costs incurred are on budget and whether the tasks are ahead or behind the baseline plan."

An atomic constituent of a model .

An action executed upon entering a state in a state machine regardless of the transition taken to reach that state.

A list of named values used as the range of a particular attribute type. For example, RGBColor = {red, green, blue}. Boolean is a predefined enumeration with values from the set {false, true}.

The specification of a significant occurrence that has a location in time and space. In the context of state diagrams , an event is an occurrence that can trigger a transition.

An action executed upon exiting a state in a state machine regardless of the transition taken to exit that state.

In the context of packages, to make an element visible outside its enclosing namespace. See: visibility. Contrast: export[OMA], import.

A string that evaluates to a value of a particular type. For example, the expression "(7 + 5 * 3)" evaluates to a value of type number.

A relationship from an extension use case to a base use case, specifying how the behavior defined for the extension use case can be inserted into the behavior defined for the base use case.

A property, like operation or attribute, which is encapsulated within a classifier, such as an interface, a class or a datatype.

A special kind of state signifying that the enclosing composite state or the entire state machine is completed.

To execute a state transition. See: transition .

A symbol on a sequence diagram that shows the period of time during which an object is performing an action, either directly or through a subordinate procedure.

Synonym: parameter .

A micro-architecture that provides an extensible template for applications within a specific domain.

A model element that may participate in a generalization relationship. See: generalization.

A taxonomic relationship between a more general element and a more specific element. The more specific element is fully consistent with the more general element and contains additional information. An instance of the more specific element may be used where the more general element is allowed. See: inheritance.

"An idiom is a low-level pattern specific to a programming language. An idiom describes how to implement particular aspects of components or the relationships between them using the features of the given language."

A definition of how something is constructed or computed. For example, a class is an implementation of a type, a method is an implementation of an operation.

The inheritance of the implementation of a more specific element. Includes inheritance of the interface. Contrast: interface inheritance .

In the context of packages, a dependency that shows the packages whose classes may be referenced within a given package (including packages recursively embedded within it). Contrast: export.

A relationship from a base use case to an inclusion use case, specifying how the behavior defined for the inclusion use case can be inserted into the behavior defined for the base use case.

The mechanism by which more specific elements incorporate structure and behavior of more general elements related by behavior. See: generalization .

An entity to which a set of operations can be applied and which has a state that stores the effects of the operations. See: object .

A specification of how stimuli are sent between instances to perform a specific task. The interaction is defined in the context of a collaboration. See: collaboration .

A general term that applies to certain types of diagrams that emphasize object interactions. These include: communication diagrams and sequence diagrams .

A named set of operations that characterize the behavior of an element.

The inheritance of the interface of a more specific element. Does not include inheritance of the implementation. Contrast: implementation inheritance .

A transition signifying a response to an event without changing the state of an object.

The organization of classifiers or packages at the same level of abstraction. A layer represents a horizontal slice through an architecture, whereas a partition represents a vertical slice. Contrast: partition.

A semantic connection between two objects. An instance of an association. See: association.

An instance of an association end. See: association end .

A specification of the conveyance of information from one instance to another, with the expectation that activity will ensue. A message may specify the raising of a signal or the call of an operation.

A class whose instances are classes. Metaclasses are typically used to construct metamodels.

A model that defines the language for expressing a metamodel. The relationship between a meta-metamodel and a metamodel is analogous to the relationship between a metamodel and a model.

A model that defines the language for expressing a model.

A generic term for all meta-entities in a metamodeling language. For example, metatypes, metaclasses, meta-attributes, and meta-associations.

The implementation of an operation. It specifies the algorithm or procedure associated with an operation

A semantically closed abstraction of a subject system. See: system.

A dimension of modeling that emphasizes particular qualities of the metamodel. For example, the structural model aspect emphasizes the structural qualities of the metamodel.

"An approach to IT system specification that separates the specification of functionality from the specification of the implementation of that functionality on a specific technology platform."

The process of generating a repository type from a published model. Includes the generation of interfaces and implementations which allows repositories to be instantiated and populated based on, and in compliance with, the model elaborated.

An element that is an abstraction drawn from the system being modeled. Contrast: view element.

Refers to something that occurs during a modeling phase of the software development process. It includes analysis time and design time. Usage note: When discussing object systems, it is often important to distinguish between modeling-time and run-time concerns. See: analysis time, design time. Contrast: run time.

A software unit of storage and manipulation. Modules include source code modules, binary code modules, and executable code modules. See: component.

An OMG-defined technology: the meta-object facility (MOF) specification defines a set of CORBA IDL interfaces that can be used to define and manipulate a set of interoperable metamodels and their corresponding models. These interoperable metamodels include the UML metamodel, the MOF meta-metamodel, as well as future OMG adopted technologies that will be specified using metamodels. The MOF provides the infrastructure for implementing CORBA-based design and reuse repositories. This definition is taken from the MOF specification version 1.3.

A semantic variation of generalization in which an object may belong directly to more than one class. See: dynamic classification.

A semantic variation of generalization in which a type may have more than one supertype. Contrast: single inheritance.

A specification of the range of allowable cardinalities that a set may assume. Multiplicity specifications may be given for roles within associations, parts within composites, repetitions, and other purposes. Essentially a multiplicity is a (possibly infinite) subset of the non-negative integers. Contrast: cardinality.

A model element with multiplicity defined whose Multiplicity Type:: upper attribute is set to a number greater than one. The term multi-valued does not pertain to the number of values held by an attribute, parameter, and so on at any point in time. Contrast: single-valued.

A string used to identify a model element.

A part of the model in which the names may be defined and used. Within a namespace, each name has a unique meaning. See: name.

An association among three or more classes. Each instance of the association is an n-tuple of values from the respective classes. Contrast: binary association.

A node is classifier that represents a run-time computational resource, which generally has at least a memory and often processing capability. Run-time objects and components may reside on nodes.

An entity with a well-defined boundary and identity that encapsulates state and behavior . State is represented by attributes and relationships, behavior is represented by operations, methods, and state machines. An object is an instance of a class. See: class, instance.

A diagram that encompasses objects and their relationships at a point in time. An object diagram may be considered a special case of a class diagram or a communication diagram. See: class diagram, communication diagram.

A state in an activity graph that represents the passing of an object from the output of actions in one state to the input of actions in another state.

A line in a sequence diagram that represents the existence of an object over a period of time. See: sequence diagram.

A service that can be requested from an object to effect behavior. An operation has a signature, which may restrict the actual parameters that are possible.

A general purpose mechanism for organizing elements into groups. Packages may be nested within other packages.

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

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

In a generalization relationship, the generalization of another element, the child. See: subclass, subtype. Contrast: child.

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.

(1) activity graphs : A portion of an activity graphs that organizes the responsibilities for actions. See also: swimlane .

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

"A set of subsystems/technologies that provide a coherent set of functionality through interfaces and specified usage patterns that any subsystem that depends on the platform can use without concern for the details of how the functionality provided by the platform is implemented."

"A model of a subsystem that contains no information specific to the platform, or the technology that is used to realize it."

"A model of a subsystem that includes information about the specific technology that is used in the realization of it on a specific platform, and hence possibly contains elements that are specific to the platform."

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

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

A predefined basic datatype without any substructure, such as an integer or a string.

(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.

A mapping from a set to a subset of it.

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

A vertex in a state machine that has the form of a state, but doesn't behave as a state. Pseudo-states include initial and history vertices.

A model which has been frozen, and becomes available for instantiating repositories and for the support in defining other models. A frozen model's model elements cannot be changed.

An association attribute or tuple of attributes whose values partition the set of objects related to an object across an association.

The handling of a stimulus passed from a sender instance. See: sender, receiver.

The object handling a stimulus passed from a sender object. Contrast: sender .

A declaration that a classifier is prepared to react to the receipt of a signal.

(1) A denotation of a model element.

A relationship that represents a fuller specification of something that has already been specified at a certain level of detail. For example, a design class is a refinement of an analysis class.

A semantic connection among model elements. Examples of relationships include associations and generalizations .

A storage place for work products (artifacts) output during process enactment, such as requuirements, results (i.e. metrics), object models, interfaces, and implementations.

A desired feature, property, or behavior of a system.

A contract or obligation of a classifier.

The use of a pre-existing artifact.

The named specific behavior of an entity participating in a particular context. A role may be static (for example, an association end) or dynamic (for example, a collaboration role).

The period of time during which a computer program executes. Contrast: modeling time .

A specific sequence of actions that illustrates behaviors. A scenario may be used to illustrate an interaction or the execution of one or more use-case instances. See: interaction, test scenario.

In the context of the MOF, a schema is analogous to a package which is a container of model elements. Schema corresponds to an MOF package. Contrast: metamodel, package corresponds to an MOF package.

A point of variation in the semantics of a metamodel . It provides an intentional degree of freedom for the interpretation of the metamodel semantics.

The passing of a stimulus from a sender instance to a receiver instance. See: sender, receiver .

The object passing a stimulus to a receiver object. Contrast: receiver .

A diagram that shows object interactions arranged in time sequence. In particular, it shows the objects participating in the interaction and the sequence of messages exchanged. Unlike a communication diagram, a sequence diagram includes time sequences but does not include object relationships. A sequence diagram can exist in a generic form (describes a general scenario) and in an instance form (describes one scenario instance). Sequence diagrams and communication diagrams express similar information, but show it in different ways. See: communication diagram.

The specification of an asynchronous stimulus communicated between instances. Signals may have parameters.

The name and parameters of a behavioral feature. A signature may include an optional returned parameter.

A semantic variation of generalization in which a type may have only one supertype . Contrast: multiple inheritance .

A model element with multiplicity defined is single valued when its Multiplicity Type:: upper attribute is set to one. The term single-valued does not pertain to the number of values held by an attribute, parameter, and so on, at any point in time, since a single-valued attribute (for instance, with a multiplicity lower bound of zero) may have no value. Contrast: multi-valued.

A declarative description of what something is or does. Contrast: implementation.

A condition or situation during the life of an object during which it satisfies some condition, performs some activity, or waits for some event.

A diagram that shows a state machine. See: state machine .

A behavior that specifies the sequences of states that an object or an interaction goes through during its life in response to events, together with its responses and actions.

A semantic variation of generalization in which an object may not change type or may not change role. Contrast: dynamic classification .

A new type of modeling element that extends the semantics of the metamodel. Stereotypes must be based on certain existing types or classes in the metamodel. Stereotypes may extend the semantics, but not the structure of pre-existing types and classes. Certain stereotypes are predefined in the UML, others may be user defined.

The passing of information from one instance to another, such as raising a signal or invoking an operation. The receipt of a signal is normally considered an event. See: message.

A sequence of text characters. The details of string representation depend on implementation, and may include character sets that support international characters and graphics.

A static feature of a model element, such as an attribute.

A model aspect that emphasizes the structure of the objects in a system, including their types, classes, relationships, attributes, and operations.

It is a classifier (e.g. class or component) with internal structure. It contains a set of parts connected by connectors. The interactions between the external environment and its internal parts can be forced to pass through a port.

A state in an activity graph that represents the execution of a non-atomic sequence of steps that has some duration.

In a generalization relationship, the specialization of another class; the superclass. See: generalization. Contrast: superclass.

A state in a state machine which is equivalent to a composite state but its contents are described by another state machine.

A state that is part of a composite state. See: concurrent substate, disjoint substate.

A subsystem is a grouping of model elements, of which some constitute a specification of the behavior offered by the other contained model elements. See also: package, system.

In a generalization relationship, the specialization of another type; the supertype. See: generalization. Contrast: supertype.

In a generalization relationship, the generalization of another class; the subclass. See: generalization. Contrast: subclass.

In a generalization relationship, the generalization of another type; the subtype. See: generalization. Contrast: subtype.

A classifier that provides services that can be invoked by others. Contrast: client.

A partition on a activity diagram for organizing the responsibilities for actions. Swimlanes typically correspond to organizational units in a business model. See: partition.

A request where the sending object pauses to wait for results. Contrast: asynchronous action.

A vertex in a state machine used for synchronizing the concurrent regions of a state machine.

(1) A collection of connected units that are organized to accomplish a specific purpose. A system can be described by one or more models, possibly from different viewpoints. Synonym: physical system.

The explicit definition of a property as a name-value pair. In a tagged value, the name is referred as the tag. Certain tags are predefined in the UML; others may be user defined. Tagged values are one of three extensibility mechanisms in UML. See: constraint, stereotype .

Synonym: parameterized software element .

A single path of execution through a program, a dynamic model, or some other representation of control flow. Also, a stereotype for the implementation of an active object as lightweight process. See: process .

A value representing an absolute or relative moment in time.

An event that denotes the time elapsed since the current state was entered. See: event .

An expression that resolves to an absolute or relative value of time.

A denotation for the time at which an event or message occurs. Timing marks may be used in constraints.

A dependency that indicates a historical or process relationship between two elements that represent the same concept without specific rules for deriving one from the other.

"A set of transformation rules that together describe how a model in the source language can be transformed into a model in the target language."

An object that exists only during the execution of the process or thread that created it.

A relationship between two states indicating that an object in the first state will perform certain specified actions and enter the second state when a specified event occurs and specified conditions are satisfied. On such a change of state, the transition is said to fire.

transition, all behavior in a

state machine is triggered by the arrival of events on one of an object's interfaces. Therefore, a trigger defines those events from which interfaces will cause the transition to be taken. The trigger is associated with the interface on which the triggering event is expected to arrive. Moreover, a transition can have multiple triggers such that an event that satisfies any one of the triggers will cause the transition to be taken.

A stereotype of class that is used to specify a domain of instances (objects) together with the operations applicable to the objects. A type may not contain any methods. See: class, instance . Contrast: interface.

An expression that evaluates to a reference to one or more types.

A set of extensions to the UML metamodel, specifying how particular UML model elements are customized and extended with new semantics by using stereotypes, constraints, tag definitions, and tagged values. A coherent set of such extensions, defined for specific purposes, constitutes a UML profile.

.

A placeholder for a type or types whose implementation is not specified by the UML. Every uninterpreted value has a corresponding string representation. See: any [CORBA].

A dependency in which one element (the client ) requires the presence of another element (the supplier ) for its correct functioning or implementation.

The specification of a sequence of actions, including variants, that a system (or other entity) can perform, interacting with actors of the system. See: use-case instance, scenario.

A diagram that shows the relationships among actors and use cases within a system.

The performance of a sequence of actions being specified in a use case. An instance of a use case. A use-case instance is a specific "end-to-end" concrete path through a use case-actors are replaced by specific persons (actor instances), specific values and responses are given and only a single path is taken through one or more possible flows of the use case. See also: scenario, test scenario.

A model that describes a system's functional requirements in terms of use cases.

A stereotype that groups global variables and procedures in the form of a class declaration. The utility attributes and operations become global variables and global procedures, respectively. A utility is not a fundamental modeling construct, but a programming convenience.

An element of a type domain.

A source or a target for a transition in a state machine. A vertex can be either a state or a pseudo-state. See: state , pseudo-state .

A projection of a model, which is seen from a given perspective or vantage point and omits entities that are not relevant to this perspective.

A view element is a textual and/or graphical projection of a collection of model elements.

A projection of model elements onto view elements. A view projection provides a location and a style for each view element.

An enumeration whose value (public, protected, or private) denotes how the model element to which it refers may be seen outside its enclosing namespace.

"A model of the software development process in which the constituent activities, typically a concept phase, requirements phase, design phase, implementation phase, test phase, and installation and checkout phase, are performed in that order, possibly with overlap but with little or no iteration."