ILS Z556
Z556 Systems
Analysis & Design
Session 5
1
Announcement
• Final specification document due date has changed:
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• Not 5/1/2015, but 4/29/2015
2
Using Language to Focus Thought
(cf., Wood, 1997)
• The language gives you a way to see:
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• a framework for interpreting the things you observe and
• a structure of understanding you can elaborate as you learn
more
3
Our Tool—Graphical
Languages
• Advantages of a graphical language:
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• a picture is worth a 1000 words
4
Models
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Too Big to See
Too Small to See
reveals relationship to the whole
supports systemic thought
creates a coherent design response
5
Work Models
• Graphical languages to capture knowledge about work
• Make concepts concrete for team discussion
“on the same page”
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Visual analysis , Complexity simplified, Focused understanding
• Help communicate with clients
Identification of breakdowns
6
5 Work Models in Contextual
Design
• Flow model
• The communication and coordination
• The detailed work steps to achieve a goal
• Artifact model
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• Sequence model
• Physical things to support the work
• Culture model
• Constraints on the work caused by policy, culture, or
values
• Physical model
• Physical structure of the work environment
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• Represents the communication coordination
necessary to make work happen
• The work must be broken into discrete parts
• How departments really coordinate work
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Flow Model (Beyer &
Holtzblatt, 1998, p. 92, 93)
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Flow Model Rules
(Beyer & Holtzblatt, 1998, p. 91)
Communication breakdowns are
shown with a lightning bolt
Flow is indicated as arrows
between bubbles
Artifacts
are shown in
boxes on the line
Automated systems and
databases usually should not
go on the flow (they are shown as a
large box with responsibilities only when they
act like a physical place or an automated
person)
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Places appear as
large boxes,
annotated with their
responsibilities
People and organization
are bubbles on the model,
and are annotated with their
position & responsibilities
People and organization
are bubbles on the model,
and are annotated with their
position & responsibilities
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Flow Model Rules
(Beyer & Holtzblatt, 1998, p. 91)
People and organization are bubbles on the model, annotated with their
position & responsibilities
Artifacts are shown in boxes on the line
Informal communication and actions are written without a box
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Flow is indicated as arrows between bubbles
Places appear as large boxes, annotated with their responsibilities
Automated systems and databases usually should not go on the flow (they are
shown as a large box with responsibilities only when they act like a physical place
or an automated person)
Communication breakdowns are shown with a lightning bolt
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Flow Model (B&H, p. 92)
President
- Run the business
Worker
Request to
-Meet w/ management
schedule meeting
w/ president
Request for
clarification
Requires lots
of iterations
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checks to sign
U1
(Secretary)
- Ensure bills paid on time
Proposal
to proof
checks
announcement
Marketing manager
- Produce proposal
Bulletin board
invoices
Vendor
-Invoice for
services
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Specifying Processes
• Structured English
• sequence
• selection
• iteration
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• is based on the logical constructs of:
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Sequence Model (see B&H p.96• Supplies the low-level, step-by-step information
on how work is actually done
• Starts with the intent and trigger for the
sequence and then lists each step in order
• Four components:
•
•
•
•
the steps by which work is done
the triggers that start a set of steps
The intents that are being accomplished
The breakdowns that prohibit workers from being
efficient
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101)
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Sequence Model – Steps
Sequence Model Trigger
• An action or the thought
preceding an action
 What causes the
sequence of actions
• Details of the tasks
depend on the scope of
the group
(May be discrete event,
based on time,
or less tangible)
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Sequence Model
(e.g., writing a memo)
• Interview Tip: Get more
details rather than less
14
Collecting Sequences During an
Interview
• Triggers (that cause the sequence of actions):
• The system needs a way to tell the user there’s something to
be done
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• may be discrete events, e.g.,???
• may be based on time, e.g.,???
• may be less tangible, e.g.,???
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Sequence Model
• Every sequence has a
primary intent, which
applies to the whole
sequence
• Secondary intent
applies to individual or
groups of steps
 Where are the problems in
the sequence
• Interview Tip: Hesitations
& Errors often show
breakdowns.
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Sequence Model - Intent
Sequence Model Breakdown
• Interview Tip: Ask how the
system could do better.
• Interview Tip: Hesitations
while thinking reveal
decision points in the
process
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Sequence Model: Example
Intent:
Hiring someone
Trigger: someone quits
Review her job
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Intent:
Review the Define candidates’ qualifications & job description
current position
Advertise the job opening
Receive applications
Intent:
Eliminate
unqualified
candidates
Review applicants
Check references of selected candidates
Fewer candidates to invite on site
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Sequence Model: Example
Choose the best candidate
Making a job offer
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Intent:
make
decisions
about
which
candidate
Set up interview dates with selected candidates
Negotiate
Candidate accepts the job Candidate denies the offer
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Choose the 2nd best candidate
• Charts activity as it moves
between different
people/groups
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UML: Activity
Diagrams—
Example
• Liner like the sequence
model, but articulates
different players like flow
model
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http://www.uml-forum.com/tools.htm
•
•
•
•
•
•
•
https://www.lucidchart.com/(good for collaboration)
http://www.gliffy.com/ (free for 5 diagrams)
http://www.diagram.ly/
http://creately.com/ ($5/month)
https://cacoo.com/ (free plan included)
http://dia-installer.de/ (open source)
https://www.draw.io/
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Tools for Creating Diagrams
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Decision Table
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Specifying Processes
• Structured English
• sequence
• selection
• iteration
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• is based on the logical constructs of:
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Limited Entry Decision Table
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• When a customer wants to purchase an item, different
conditions determine the actions you should take.
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Limited Entry Decision Table
• Under $50?
• Pays by check w/ 2 forms of ID?
• Uses credit card?
• Next, identify the actions
• Ring up sale
• Call supervisor for approval
• Require a signature that matches one on the back of the card
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• First, identify the conditions:
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Limited Entry Decision Table
N
N
Pays by check w/ 2 forms
of ID
Uses credit card
Y
N
Y
N
N
Y
N
Y
Ring up sale
X
X
Call supervisor for approval
Require a signature that
matches one on the back
of the card
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Y
actions
Y
conditions
Under $50
X
X
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General Rule
• Check the number of rules
N
• M = M x M x M x M . . . (M to the nth power)
3
• E.g., 2 = 2 x 2 x 2 = 8rules
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• The number of answer: M (e.g., 2 for Y/N)
• The number of condition: N
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Mixed Entry Decision Table
Y
Order value $ 049
Y
N
50- >
099 100 49
X
0
10
%
15% 0
N
N
50- >
99 100
X
5% 10
%
actions
Free shipping
Discount
given
Y
conditions
Regular
customer?
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Decision Tree: Hiring an Info
Architect
Formal
education in IA
yes
yes
no
Job
Applicant
no
yes
no
Practical
exp in IA
yes
Action
Job offer
no
yes
Keep app
Keep app
no
yes
Reject
Keep app
no
yes
Reject
Reject
no
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College
degree
28
Reject
• This is your last semester at ILS, and you are
ready to look for jobs. You need to go through
job postings and decide which jobs to apply for.
Draw a decision tree or table with:
• three conditions
• three actions
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Exercise: Decision Tree/Table
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Exercise: Flow Model
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• Form 4 groups (5 people each)
• Develop a flow model based on the case
presented in Alter’s article
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Modeling
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• What constitutes a good model?
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