Glossary of Unified Modeling Language Terms - A

A

• 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 data type
• 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 procedure entities 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.
• Active class - a class defining active objects
• Active object - an object running under its own thread
• Activity - carrying out behaviour in a State machine diagram
  • 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.)
• Actor - a role that a user takes when invoking a use case. Also see actor modeling.
• 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.