In the
Unified Modeling Language
The Unified Modeling Language (UML) is a general-purpose visual modeling language that is intended to provide a standard way to visualize the design of a system.
UML provides a standard notation for many types of diagrams which can be roughly ...
, an action
[
]
is a named element that is the fundamental unit of executable functionality. Actions take a set of inputs, which may be empty, and convert them to a set of outputs, which in turn may also be empty.
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The execution of an action represents some transformation or processing in the modeled system. An action execution represents the run-time behavior of executing an action within a specific behavior execution. All action executions will be executions of specific kinds of actions because action is an ]abstract class
In object-oriented programming, a class defines the shared aspects of objects created from the class. The capabilities of a class differ between programming languages, but generally the shared aspects consist of state ( variables) and behavior ( ...
. When the action executes, and what its actual inputs are, is determined by the concrete action and the behaviors in which it is used.
An action is the specification of an executable
In computer science, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instruction (computer science), in ...
statement
Statement or statements may refer to: Common uses
*Statement (computer science), the smallest standalone element of an imperative programming language
*Statement (logic and semantics), declarative sentence that is either true or false
*Statement, ...
and is the fundamental unit of processing or behavior in an activity node
In general, a node is a localized swelling (a "knot") or a point of intersection (a vertex).
Node may refer to:
In mathematics
* Vertex (graph theory), a vertex in a mathematical graph
*Vertex (geometry), a point where two or more curves, lines ...
that represents some transformation in the modeled system.
An action forms an abstraction of a computational procedure which is an atomic execution and therefore completes without interruption. An action is considered to take zero time and cannot be interrupted. In contrast, an activity is a more complex collection of behavior that may run for a long duration. An activity may be interrupted by events, in which case it does not run to completion.
An action is a result of a system state
State most commonly refers to:
* State (polity), a centralized political organization that regulates law and society within a territory
**Sovereign state, a sovereign polity in international law, commonly referred to as a country
**Nation state, a ...
change and is realized by sending a message to an object
Object may refer to:
General meanings
* Object (philosophy), a thing, being, or concept
** Object (abstract), an object which does not exist at any particular time or place
** Physical object, an identifiable collection of matter
* Goal, an a ...
or modifying a link or a value of an attribute.
An action may receive inputs in the form of control flows and object flows (the latter via input pins) and passes the results of its processing or transformations to one or more outgoing control flows or object flows (the latter via output pins) and onto downstream nodes.
Execution of the action cannot begin until all its prerequisites are satisfied. All incoming control flows have control tokens and all input pins have object tokens.
An action refers to the suite of rules and policies associated with a state machine
A finite-state machine (FSM) or finite-state automaton (FSA, plural: ''automata''), finite automaton, or simply a state machine, is a mathematical model of computation. It is an abstract machine that can be in exactly one of a finite number o ...
state
State most commonly refers to:
* State (polity), a centralized political organization that regulates law and society within a territory
**Sovereign state, a sovereign polity in international law, commonly referred to as a country
**Nation state, a ...
, and is represented as an object
Object may refer to:
General meanings
* Object (philosophy), a thing, being, or concept
** Object (abstract), an object which does not exist at any particular time or place
** Physical object, an identifiable collection of matter
* Goal, an a ...
method.
Actions are contained within and are provided context by activities.
An action behavior accompanies a transition event.
Action types
*''On Entry'': occurs when an activity is entered.
*''Do'': occurs while an activity is occurring. These are the steps within the activity.
*''On Exit'': occurs when you leave an activity.
*''On Event'': occurs upon a specific event.
References
Unified Modeling Language
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