Analysis and Specification of Information
Systems
Spring 2007
Session 9: Activity Diagrams
Eran Toch
erant@tx.technion.ac.il
Specification and Analysis of Information Systems Spring 2005 1

Outline
• Introduction
• Basics
– Activities, Tokens, objects, signals
• Structures
– Decomposition
2

Modeling Process
Phase Actions Outcome
Business
Initiation Raising a business need
documents
Interviewing stakeholders, exploring the Organized
Requirements system environment documentation
Analyze the engineering aspect of the Formal
Specification system, building system concepts specification
Define architecture, components, data Formal
Design types, algorithms Specification
Program, build, unit-testing, integrate, Testable
Implementation documentation system
Testing & Integrate all components, verification, Testing results,
Integration validation, installation, guidance Working sys
System
Maintenance Bug fixes, modifications, adaptation
versions
Intro | Basics | Structures 3

Behavior Modeling
Sequence Diagrams State Diagrams Activity Diagrams
Checkout Order Add to cart
Manager
message: create
In process
Order Check
supplied availability
message: change [problem] [okay]
status
Inventory
Notify Supply
User Order
Intro | Basics | Structures 4

Strengths
• Best for modeling complex behavior
– Which does not rely on interactions.
– Has parallel behavior.
• Examples:
– Business workflow (authorizing a loan).
– User behavior (login/logout).
– Algorithms.
Intro | Basics | Structures 5

Outline
• Introduction
• Basics
– Activities, Tokens, objects, signals
• Structures
– Decomposition
6

Customer Service Modeling
Intro | Basics | Structures 7

Activity Diagram for Customer Service
Start Action
Fork
decision
merge
Join Final Node
Intro | Basics | Structures 8

Tokens
• The conceptual model of activity diagrams is based
on tokens.
Intro | Basics | Structures 9

Tokens
The initial node creates a
single token
An action requires a token
to execute, and produce a
token when it ends
Each fork node generates
tokens, according to the
number of paths.
Each join “collects” all the
incoming tokens,
producing a token
afterwards.
Intro | Basics | Structures 10

Object Flows
• Objects describe the interface between actions
Object Receive Call Call Data Log Call
Flow
Call data
Pins Receive Call Log Call
Call data
Call data
Initiate Call
Intro | Basics | Structures 11

Pins
• Pins declare the interface between two actions.
Output
Pin
Input
Pin
Parameter
Transformation
Intro | Basics | Structures 12

Objects with States
• Object nodes allow state change modeling:
Call Data Find Customer Call Data
Receive Call
[created] Type [classified]
Intro | Basics | Structures 13

Data Store
• A datastore is a stereotype for an object which stores
objects persistently.
All entering
tokens are
copied so that
tokens never
leave the data
store
If a token already
present in the data
store, it replaces the
old one
Intro | Basics | Structures 14

Catching Signals
Time Signal Event Signal
Flows when the
time expression Flows when an Sends an event
is true event occurs when a flow
enters
Intro | Basics | Structures 15

Example: Volvo Blind Spot Info System (BLIS)
Intro | Basics | Structures 16

BLIS
Camera Behavior Safety Controller Behavior
Side Object
Check Objects Detected
in Camera
Is object
[no] Detected? Detection data
[yes]
Alarm Deciding
Side Object
Detected Side?
[left] [right]
Left Alarm Right Alarm
Intro | Basics | Structures 17

Outline
• Introduction
• Basics
– Activities, Tokens, objects, signals
• Structures
– Decomposition
18

Final Nodes
the activity is terminated when the activity is terminated when
the first token arrives all tokens in the graph are
destroyed
Intro | Basics | Structures 19

Decomposition
• An action can be decomposed into an subactivity.
• The invoked activity graph can be used by many
subactivity states.
Input
Parameter Final Action
Intro | Basics | Structures 20

Partitions
• Partitions (swimlanes) can group actions by:
– class, business unit, person etc…
• Can be multidimensional (not always possible).
Management
Evaluate Revise
Impact Plan
[ priority = 1]
Support
Register Release
Bug Fix
Engineering
Fix Test
Bug Fix
Intro | Basics | Structures 21

Pre / Post Conditions
for Decompositions
for Actions
Intro | Basics | Structures 22

Exceptions
• Exception represent errors and unexpected
situations
Exception
Edge
interruptible Exception
region Handler
What happens
to the tokens?
Intro | Basics | Structures 23

Exception – cont’d
Multiple events
Actions can
Multiple event
throw events too
handlers
Exception info
can be modeled
Intro | Basics | Structures 24

Summary
 Activity Diagrams:
– Represent workflows
– Good for designing activities
 Basic Elements
– Activities
– Objects
– Signals
 Structures
– Tokens
– Decomposition
– Interfaces
25