Activity Diagram

UML Lecture Series

UML SIG

UML for Business Modeling (Activity Diagram)

UML SIG – UML Lecture Series UML for Business Process Modeling – Activity Diagram

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Session Objectives

1. Explain the role of UML in modelling.2. Demonstrate the use of activity diagrams in

business modeling. 3. Apply basic and advanced elements of activity

diagram notations. 4. Demonstrate the use of activity diagrams in

systems modeling.5. Awareness of typical mistakes made by students.

At the end of this session, YOU should be able to:


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Keywords

Business modellingActivity stateTransitionTriggerless transitionSynchronisation barStart stateStop/End stateBranchGuardForkJoinConcurrent threadAlternative threadConditional threadSystem modelling


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Session Objectives







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Why Model?

Captures Processes

Enhances Communication

Manages Complexity

Defines Architecture

Enables Reuse


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Introduction to UML

UML is a language for visualising, specifying, constructing and documenting the artifacts of a software intensive system.

Open Specification by OMG (Object Management Group).

Current standard is UML 2.0. However, most students use UML 1.4 which is sufficient for most academic projects.

UML is an analysis and design technique. It has to be used together with a process in a development environment.


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Overview of UML Diagrams


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Thoughts to Ponder …

If you reuse code,You'll save a load,

But if you reuse design,Your future will shine.

Ralph E. Johnson.


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… What is design? ... It’s where you stand with a foot in two worlds—the world of technology and the world of people and human purposes—and you try to bring

the two together.

Terry Winograd, “Bringing Design to Software”, Addison Wesley, Stanford University and Interval Research Corporation, With John Bennett, Laura De

Young, and Bradley Hartfield, ISBN: 0-201-85491-0. 310

Thoughts to Ponder …


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Session Objectives







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Business Modelling


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Activity Diagram

In its basic form, an activity diagram is a simple and intuitive illustration of what happens in a workflow, what activities can be done in parallel, and whether there are alternative paths through the workflow.

Historically, activity diagrams have mostly been used in the business process modeling domain but are also useful in system modelling.


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Business Modelling

This example is a proposal

process, taken from an

organization that sells telecom network

solutions.


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Session Objectives







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Basic Notations

Start State

Activity State

Decision (branch)

Synchronisation bar

Stop/End State

Concurrent thread

Alternative thread

Transition


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Activity Diagram - Notations

1. Activity states, represent the performance of a step within the workflow.

2. Transition show what activity state follows after another.

3. Decisions (branch) for which a set of guard conditions are defined. These are conditions that must be met to trigger the transition.

4. Synchronization bars, which you can use to show parallel subflows. Synchronization bars allow you to show concurrent threads - fork or join.


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Advanced Notations

Guard conditions can

be used to show that one of a set of concurrent

threads is conditional.

Conditional Threads


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Advanced Notations

An activity state may reference another activity diagram, which shows the internal structure of the activity state by having a nested activity graphs. You can either show the sub-graph inside of the activity state or let the activity state refer to

another diagram

Nested Activity Diagrams


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Advanced Notations Nested Activity Diagrams


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Advanced Notations

The contents of an activity diagram may be organized into partitions (swimlanes) using solid

vertical lines. A partition does not have a formal semantic interpretation, but is, in business modeling, often used to represent an organizational unit

of some kind

Partitions


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Session Objectives







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Systems Modelling

Just as you would use an activity diagram to show the structure of a workflow, you could also use it to show the structure of a flow of events of a system use case


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System Modelling


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Session Objectives







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Common Mistake Made by Students

1. Business Modelling (activity diagram) which appears like system modelling.

2. Students tend to be overly software centric paying little emphasis on the underlying problem statement which has to be mapped first (business modelling).


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True/False

1. Business modelling is typically done before system modelling.

2. Alternative thread must go along with a branch.3. A branch can have at most THREE (3) alternative

threads4. Fork: One incoming transition and two or more

outgoing transition.5. Branch: Two or more incoming transition and one

outgoing transition.6. Synchronisation bar allow sequential threads.7. Conditional threads are also called triggered transitions

and must be shown with a guard condition. 8. Transitions without guard conditions are called

triggerless transitions.


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Summary

1. Role of UML in systems modelling.2. Basic elements of activity diagrams are activity states,

transitions, decisions, and synchronization bars. 3. Activity diagrams can be used to show concurrent

threads, and alternative threads, as well as conditional threads in a workflow.

4. Activity diagrams can be used to illustrate the workflow of business processes - called business modelling.

5. Activity diagrams can be used to illustrate the flow of events of a use case – for systems modelling.

6. Awareness of typical mistakes by students.


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Reference

Ericsson M. 2004, “Activity Diagram: What They Are and How To Use Them” Level: Advanced, The Rational

Edge, IBM


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Lab Session

Draw the adjacent

diagram in Visual Paradigm


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Q & A

Question and Answer Session

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Activity Diagram

Technology

use of activity diagrams

uml uml

nested activity graphs

systems modeling

overview of uml diagrams

role of uml

basic notations

session objectives