UML activity diagram: Difference between revisions

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item(iGuard)("still hungry")(obj.sw = enough.e + (20, 0));
item(iGuard)("still hungry")(obj.sw = enough.e + (20, 0));
item(iGuard)("had enough")(obj.nw = enough.s + (0, -4));
item(iGuard)("had enough")(obj.nw = enough.s + (0, -4));
</uml>
=== Activity edges (links) ===
; Control edges
These edges can be drawn with '''arrows''' in various ways:
<uml>
Activity.A("Do A");
Activity.B("Do B");
leftToRight(20)(A,B);
drawObjects(A,B);
clink(transition)(A,B);
</uml>
* Represented by an arrow from an activity showing parameters with pins from a node to another
* An arrow to a '''connector''' (a small circle with a letter) and then from a same connector to a activity node
* Activity node to object node to activity node (with arrows)
; Object Flow edges
* Represented by an arrow
<uml>
</uml>
</uml>


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; Output signal (send)
; Output signal (send)
* Represented by a convex polygon
* Represented by a convex polygon
=== Activity edges (links) ===
; Control edges
These edges can be drawn with '''arrows''' in various ways:
* Represented by an arrow from an activity node to another
* Represented by an arrow from an activity showing parameters with pins from a node to another
* An arrow to a '''connecto'''r (a small circle with a letter) and then from a same connector to a activity node
* Activity node to object node to activity node (with arrows)
; Object Flow edges
* Represented by an arrow


=== Partitions and subactivities ===
=== Partitions and subactivities ===
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== Typical patterns ==
== Typical patterns ==


Inspired from [http://www.visual-paradigm.com/VPGallery/diagrams/Activity.html Activity
Inspired from [http://www.visual-paradigm.com/VPGallery/diagrams/Activity.html Activity Diagram] and [http://www.omg.org/technology/documents/formal/uml.htm Unified Modeling Language (UML), version 2.1.2] specification.
Diagram] and [http://www.omg.org/technology/documents/formal/uml.htm Unified Modeling Language (UML), version 2.1.2] specification.


(stub section, needs to be completed).
(stub section, needs to be completed).

Revision as of 17:29, 11 June 2008

Draft

Definition

UML activity diagrams refer to software engineering method modeled with UML to describe work flows, business processes and other procedures.

UML activity diagrams are a kind of behavior diagram, i.e. is a kind of UML behavioral modeling. UML activity diagrams are somewhat similar UML state machine diagrams. Both are somewhat similar to Petri nets.

See also: UML, UML behavioral modeling

Introduction

Activity modeling means to describe sequencing and conditions of actions. Such descriptions commonly are control flow and object flow models.

Simple Activity diagrams consist of:

  • Initial node.
  • Activity final node.
  • Activities in between

Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

“The starting point of the diagram is the initial node, and the activity final node is the ending. An activity diagram can have zero or more activity final nodes. In between activities are represented by rounded rectangles.” (Wikipedia, retrieved 11:08, 4 June 2008 (UTC).

Architecture of activity diagrams

Basic Nodes

According to Conrad Bock (2003), there there are three kinds of nodes in activity models:

  1. Action nodes operate on control and data values that they receive, and provide control and data to other actions.
  2. Control nodes route control and data tokens through the graph. These include constructs for choosing between alternative flows (decision points), for proceeding along multiple flows in parallel (forks), and so on.
  3. Object nodes hold data tokens temporarily as they wait to move through the graph. Figure 3 shows the notation for some of the activity nodes to be discussed. Contrary to the names, control nodes coordinate both data flow and control flow in the graph, and object nodes can hold both objects and data
Action nodes

Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

  • Represented by a rectangle with rounded corners (drawn in slightly different ways depending on the software used ...)
  • Action nodes should have a label
Object nodes
  • Represented by a rectangle with a label

Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

Decision and merge control node
  • Represented by a lozange

Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

Fork and join control node
  • Represented by a horizonal or vertical line
  • One or more activities can join
  • One or more activities can fork

Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

Initial node
  • Represented by a fat black dot
  • There can be only one initial (starting) node

Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

Final nodes
  • A fat black dot inside a circle (bull's eye symbol)
  • A circle with an x represents the end of a flow (not the whole activity)

Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

Below is a complete example (copied June/2008 from the MetaUML website):

Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

Activity edges (links)

Control edges

These edges can be drawn with arrows in various ways: Diagrams error (with plantuml command): /bin/bash: plantuml: command not found

  • Represented by an arrow from an activity showing parameters with pins from a node to another
  • An arrow to a connector (a small circle with a letter) and then from a same connector to a activity node
  • Activity node to object node to activity node (with arrows)
Object Flow edges
  • Represented by an arrow


Signals

Actions in a diagram also can respond to signals (instead of the flow)

Time signals
  • Represented like an hour glass
Input Accept signal (accept)
  • Represented by a concave pentagon (a smashed-in rectangle)
Output signal (send)
  • Represented by a convex polygon

Partitions and subactivities

Subactivities
  • Activities can be decomposed into subactivities
  • A rake in an action node signals a subactivity
  • The subsidiary activity diagram has an input and an output parameter (object nodes)
Partititions
  • An activity can be partitioned in a swimlanes
  • Each swimlane (partition) typically represents a player or role (e.g. learner A, learner B, group A, teacher). See below for some examples

Typical patterns

Inspired from Activity Diagram and Unified Modeling Language (UML), version 2.1.2 specification.

(stub section, needs to be completed).

Accept Event Action
  • An action that waits for the occurrence of an event meeting specified conditions
Activity Final
Data Store
Decision Node
Flow Final
Fork Node
InitialNode
Join Node
Merge Node
Object Node
Send Signal Action
Object Flow

Examples

A simple example

The following example taken from D7.2 UNFOLD outcomes 2 contains the following elements:

  • A start node
  • An end node
  • Two join/break (the fat lines)
  • Three activities
UML activity diagram example

Educational examples

Activity diagrams can be used to describe learning designs of CSCL scenarios. A good example are collaborative learning flow pattern (Hernández-Leo et al., 2005b).

Below some more pictures that show that activity diagrams are popular withing the IMS Learning Design community.

The next example shows a diagram for competency-based learning with two major alternatives, advising-then-anticipating and anticipating-then-advising. (IMS LD Best Practice specification)

Activity Diagram for Competency-based learning. Source: IMS

The following example taken from the IMS LD Best Practice specification shows a diagram for problem-based learning

Activity Diagram for Problem Based Learning. Source: IMS

Links

Summaries of UML activity diagrams
Introductions to activity diagrams
Standards
  • Unified Modeling Language (UML), version 2.1.2. There are two specifications that comprise the UML 2.1.2 specification: Superstructure and Infrastructure. There are also two specifications that relate to the UML2 specification (Diagram Interchange and Object Constraint Language).

References

Bock, Conrad (2003). "UML 2 Activity and Action Models", Journal of Object Technology, vol. 2, no. 4, July-August 2003, pp. 43-53. http://www.jot.fm/issues/issue_2003_07/column3

  • Fowler, M. (2000). UML distilled (3rd ed.). Upper Saddle River, NJ: Addison-Wesley. ISBN 0321193687
  • Hernández-Leo, D., Asensio-Pérez, J.I., Dimitriadis, Y., Bote-Lorenzo, M.L., Jorrín-Abellán, I.M., Villasclaras-Fernández, E.D. (2005b). Reusing IMS-LD Formalized Best Practices in Collaborative Learning Structuring. Advanced Technology for Learning 2(4):223-232. http://dx.doi.org/10.2316/Journal.208.2005.4.208-0865 - PDF
  • IMS Global Learning consortium (2003). IMS Learning Design Best Practice and Implementation Guide, HTML, retrieved 11:08, 4 June 2008 (UTC).
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