Glossary of Unified Modeling Language (UML) terms provides a compilation of terminology used in all versions of UML, along with their definitions. Any notable distinctions that may exist between versions are noted with the individual entry it applies to.
Abstract - An indicator applied to a classifier (e.g., actor, class, use case) or to some features of a classifier (e.g., a class's operations) showing that the feature is incomplete and is intended not to be instantiated, but to be specialized by other definitions.
Abstract class - A class that does not provide a complete declaration, perhaps because it has no implementation method identified for an operation. By declaring a class as abstract, one intends to prohibit direct instantiation of the class. An abstract class cannot directly instantiate objects; it must be inherited from before it can be used.
Abstract operation - Unlike attributes, class operations can be abstract, meaning that there is no provided implementation. Generally, a class containing an abstract operation should be marked as an abstract class. An Operation must have a method supplied in some specialized Class before it can be used.
Abstraction is the process of picking out common features and deriving essential characteristics from objects and procedureentities that distinguish it from other kinds of entities.
Action - An action is the fundamental unit of behaviour specification and represents some transformation or processing in the modeled system, such as invoking a method of a class or a sub activity
Action sequence -
Action state -
Action steps -
Activation - the time during which an object has a method executing. It is often indicated by a thin box or bar superimposed on the Object's lifeline in a Sequence Diagram
Activity diagram - a diagram that describes procedural logic, business process or work flow. An activity diagram contains a number of Activities and connected by Control Flows and Object Flows.
Do - a type of Activity which may be interrupted, as opposed to normal Activities which may not be interrupted
Internal - an Activity that is executed within a State
Entry - an Activity that is executed when a State is entered
Exit - an Activity that is executed when a State is exited
Activity final - the end point of an activity diagram. When a thread reaches an Activity Final node, all the threads of the activity terminate. (Contrast with Flow Final node, which marks the end of one thread.)
Aggregation - 1. a special type of association used to represent a stronger relationship between two classes than a regular association; typically read as "owns a", as in, "Class A owns a Class B". A hierarchy of classes where the child object may or may not continue to exist if the parent object is destroyed; see 'composition'. 2. An aggregation is a structural relationship that specifies that one class represents a large thing which constitute of smaller things and represents "has-a" relationship.
Artifact - items that model physical pieces of information in your system, such as a user's manual, training material, or password file
Association - 1. a relationship with 2 or more ends, where each end is on a class (or other classifier). Each end is called a Role, and may have a role name, Multiplicity, and may be Navigable. 2. An association is a structural relationship that specifies that the objects of one thing are connected with the objects of another.
Association class - a class that describes an association.
Asynchronous - The sender of an asynchronous message does not wait for a response.
Attribute - a significant piece of data owned by a Class, often containing values describing each instance of the class. Besides the attribute name and a slot for the attribute value, an attribute may have specified Visibility, Type, Multiplicity, Default value, and Property-string.
Cardinality - the current number of occurrences of a Property. The cardinality must be a value that is allowed by the multiplicity
Child -
Class - the primary declarative construct of object-oriented programming; a cohesive unit of Attributes and Operations; a compile-time template for an Object
Class diagram - a type of static structure diagram that describes the structure of a system by showing the system's classes, their attributes and the relationships between the classes.
Classifier - a category of UML elements that have some common features, such as attributes or methods.
Client -
Collaboration - A collaboration is a society of classes, interfaces and other elements that work together to provide some cooperative behavior that is bigger than the sum of its parts.
Component - A component represents a software module (source code, binary code, executable, DLL, etc.) with a well-defined interface. The interface of a component is represented by one or several interface elements that the component provides. Components are used to show compiler and run-time dependencies, as well as interface and calling dependencies among software modules. They also show which components implement a specific class.
Composition - a specific type of relationship describing how one Object is composed of another Object; a form of Aggregation where the child object is destroyed if the parent object is destroyed.
Condition -
Connection -
Constraint - natural language, programming language or Object Constraint Language boolean condition which may not be false if a Class is to be considered valid
Containment - containment by value and containment by reference. Containment by value implies that an object contains another object; containment by reference implies that an object contains a pointer to another object.
Decision - a point in an Activity diagram where a Flow splits into several, mutually exclusive, Guarded flows. A Merge marks the end of the optional behaviour started by the Decision
Dependency - a dependency exists between two defined elements if a change to the definition of one would result in a change to the other. In UML this is indicated by a line pointing from the dependent to the independent element.
Encapsulation - a means to bind together code and the data it uses. It is the basis of object oriented programming.
Entity -
Enumeration - a set of constant values for a new data type
Event - when it occurs on an Object it may cause a Transition in a State machine diagram
Expansion region - a set of Actions in an Activity diagram that occur once for each of a collection of input Tokens to the Expansion Region
Extend - a means to use a class as a starting point for creation of a new class. The new class inherits all of the attributes, properties, and methods of the class it extends.
Generalization - a relationship between a specific classifier (typically a class) to a more general classifier asserting that the general classifer contains common features among both the specific classifier and the general classifier. Features include, for example, properties, and constraints. The use of generalization is often logically restricted to cases where the specific classifier is a "kind-of" or "sort-of" the general classifier: for example, a Boxer is a "kind-of" Dog. When the classifiers involved are software engineering classes, generalization usually involves reusing code; it is often implemented using inheritance, where the more specific code reuses the more general code.
Generalization Tree - Several specialized classifiers may point to the same general classifier, forming a generalization tree, where the general classifer contains common features shared by all the specialized versions. As generalization is a relationship, it is possible for a classifer to participate in several generalizations, often being on the specific end or on the general end, forming a directed acyclic graph (DAG) (i.e., no loops).
Initial pseudostate - points to the initial State of an Object
Instance - An instance is a concrete manifestation of an abstraction to which a set of operations can be applied and which has a state that stores the effect of the operation.
Interaction Frame - a section of a Sequence diagram, divided into fragments, which is subject to an algorithmic Operator such as iteration, parallelism or optionality.
Join - a point in an activity diagram where several concurrent flows (threads) synchronize, waiting until all are complete before continuing with a single flow
Merge - a point in an activity diagram marking the end of the optional behavior started by a Decision
Message - a signal from one object (or similar entity) to another, often with parameters. Often implemented as a call to a Method, including the Constructor and Destructor, of an Object in a Sequence diagram.
Multiplicity - 1. A specification of the number of possible occurrences of a property, or the number of allowable elements that may participate in a given relationship. In UML 1.x, it was also possible to have a discrete list of values, but this was eliminated in UML 2.0. 2. It specifies how many objects may be connected across an instance of an association which is written as a range of values (like 1..*).
Mandatory - A required multiplicity, the lower bound is at least one, usually 1..1 or 1
Optional - The lower bound is at most zero, usually, 0..1
Many - A multiplicity with no upper limit, either 0..* or *
Forbidden - No elements allowed, 0..0 (in UML 2.2)
Navigable - the ability for objects of a Class at one end of an Association to retrieve Objects from the other end. Associations need not be navigable.
Node -
Note - It is an explanatory part of UML models. A note is a symbol for rendering constraints and comments attached to an element or collection of elements.
Object - a runtime instance of a Class. Objects are rarely shown on diagrams (because there are usually too many) unless they are used to illustrate some scenario, test, etc. Such Objects are often shown with the Attributes of the Class populated with sample data
Object Constraint Language (OCL) - a declarative language for describing rules and constraints that apply to UML models
Polymorphism - the ability of Objects belonging to different Classes to respond to Operations of the same name, each one according to the right Class-specific behaviour
Profile - Provides a generic extension mechanism for building UML models. Other extension mechanisms include stereotypes.
Property - an Attribute or an Association
Property-string - a qualifier for Attributes and Operations. Examples include {ordered}, {readonly}, {unique}.
Qualified association - tightens the multiplicity or role of an association between 2 classes by dividing the set of objects into subsets based on a value of the qualifier—an attribute of the target objects, association objects, or some a derived attribute of the target or association objects.
Realization - Realization shows the relationship between an Interface and the class that provides the implementation for the interface.
Reference -
Request - The input to the system for finding the related abstracts from different operations (Add, Del, Mod, Inq.). Request could be for only one for every operation
Response - The output of the "Request". Response could be 1 or more for a single request.
Relation -
Return - a reply that may be issued from a Method following a Message
Role - description of the part played in an Association by one of the Classes in the Association
Scenario - a narrative describing foreseeable interactions
Self-call - a Message from an Object to one of its own Methods
Sequence diagram - describes the Messages sent between a number of participating Objects in a Scenario
Signal - an Event which can occur in an Activity diagram in three different ways: as a Time Signal, as a signal which an Activity can listen for and a signal which an Activity can send
State - an Object exists at one of the States described in a State machine diagram. A state encompasses all the properties of the object along with the values of each of these properties.
State machine diagram - describes the lifetime behaviour of a single Object in terms of in which State it exists and the Transition between those States
Static attribute - an attribute that does not relate to a specific object but is at class level; that is, an attribute that is common among all objects of that class
Static modeling - use of class diagrams to describe structure
Static operation - an operation that does not relate to a specific object but is at class level
Transition - 1. movement from one State to another in a State machine diagram. The transition is specified by its Trigger-signature [Guard]/Activity 2. a relationship between two states indicating that when a specific event occurs and specific conditions are satisfied an object in the first state will perform certain actions and enter the second state.
Type - the options are: an elementary Value type such as integer, string, date, or Boolean or a Reference type defined in a Class
Use case - A use case can be defined as a sequence of actions, including variations, that the system can execute and that produce an observable result which has some value for an actor that interacts with the system
Visibility - the availability for access of elements in a model. Typically used to limit the visibility of features defined by a Class (e.g., attributes, operations). When applied to features defined by a class, the standard options are:
private (-): available only within the Class in which it was defined. This is the most limited visibility
protected (#): available within any subclass of this class and within the package which directly contains the defining Class
package (~): available only within the Package which directly contains the defining Class
public (+): available to any Class that can see the defining Class. This is the least limited visibility.
