CS 501: Software Engineering
Lecture 4
Project Management
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CS 501 Spring 2005
Administration
Projects
• Announcements by project teams
Quiz 1
• Quiz 1 is next Thursday. Information is posted on the web
site.
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OS 360
The operating system for the IBM 360 was two years late.
Question: How does a project get two years behind
schedule?
Answer: One day at a time!
Fred Brooks Jr., The Mythical Man Month
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The Aim of Project Management
To complete a project:
• On time
• On budget
• With required functionality
• To the satisfaction of the client
• Without exhausting the team
To provide visibility about the progress of a project
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Aspects of Project Management
Planning
• Outline schedule during feasibility study
• Detailed schedule at the beginning of a project or phase
of a project
Progress tracking
• REGULAR COMPARISON OF PROGRESS AGAINST
PLAN
Final analysis
• Analysis of project for improvements during next project
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Terminology
Deliverable
Work product that is provided to the customer (report,
presentation, documentation, code, etc.)
Milestone
Completion of a specified set of activities (e.g., delivery
of a deliverable)
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Terminology
Activity
Part of a project that takes place over time (also known as
a task).
Event
The end of a group of activities.
Dependency
An activity that cannot begin until some event is reached
Resource
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Staff time, equipment, or other limited resources required
by an activity.
CS 501 Spring 2005
General Approach to Project Planning
Identify deliverables and milestones
Divide project into activities (tasks)
For each task estimate:
•
time to complete from when activity begins
•
dependencies on events before beginning
•
resource requirements
Build a model that uses this data to create a work-plan, including
schedule, resource allocation, and flexibility
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Project Planning Methods
Critical Path Method, Gantt charts, Activity bar charts, etc.
•
Build a work-plan from activity data.
•
Display work-plan in graphical form.
Project planning software (e.g., Microsoft Project)
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•
Maintain a database of activity data with input tools
•
Calculate and display schedules
•
Provide progress reports
CS 501 Spring 2005
Project Planning Methods
All project planning methods are best when:
1. Plan is updated regularly (e.g., weekly or monthly)
2. The structure of the project is well understood
3. The time estimates are reliable
4. Activities do not share resources
Unfortunately, #2, #3, #4 rarely apply to software
development
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A Simple Gantt Chart
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Source: Microsoft using Excel
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A More Complex Gantt Chart
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Source: SmartDraw
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Gantt Charts
• Dates run along the top (days, weeks or months).
• Each row represents an activity. Activities may be scheduled
sequentially, in parallel or overlapping.
• The scheduled for an activity is a horizontal bar. The left end
marks the planned beginning of the task. The right end marks the
expected end date.
• The chart may be updated by filling in each activity to a length
proportional to the work accomplished.
• Progress to date can be compared with the plan by drawing a
vertical line through the chart at the current date.
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Activity Graph
A scheduling technique that emphasizes dependencies
An activity
A dummy activity
An event
A milestone
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Example: Activity Graph
An Open University Course
Deliverables:
16
8
8
4
1
4
15
Written texts (bound in pairs)
Television programs
Radio programs
Computer programs
Home experimental kit
Assignments and sample solutions
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Activity Graph (part)
other
activities
START
16
Revise
Unit 3
Edit
Unit 3
Print
Unit 3
Mail
Unit 3
END
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Activity Graph (continued)
other
activities
Revise
Unit 3
Edit
Unit 3
START
other
activities
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Revise
Unit 4
Edit
Unit 4
Typeset
Unit 3
Print
Units 3/4
Mail
Units 3/4
Typeset
Unit 4
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Activity Graph (continued)
Script
TV 2
Edit
Unit 3
Make
TV 2
START
Edit
Unit 4
Mail
Document
Computer 1
Program
Computer 1
Prototype Computer 1
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Scheduling: Background
PERT
Program Evaluation and Review Technique introduced by the
U.S. Navy in 1957 to support the development of its Polaris
submarine missile program.
PERT/Time
Activity graph with three time estimates (shortest, most probable,
longest) on each activity to compute schedules.
PERT/Cost
Added scheduling of resources (e.g., facilities, skilled people,
etc.)
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Critical Path Method
Uses Activity Graph with single time estimate for each activity to
estimate:
earliest start date -- every activity begins at first possible time
latest start date -- every activity begins at the last possible time
slack -- difference between the latest and earliest start dates
A standard method for managing large construction projects.
On big projects, activity graphs with more than 10,000 activities
are common.
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Time Estimates for Activities (Weeks)
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1
3
2
6
12
3
12
3
3
2
4
1
1
2
8
4
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Earliest Start Dates
All activities beginning at a given event
have the same earliest start date.
1
1
12
4
3
5
15
2
17
3
12
0
12
12
3
15
17
6
20
22
23 24
1
23
3
2
19
2
4
4
22
4
1
25
8
8
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Latest Start Dates
Each event must be achieved by the date
shown or the final date will not be met.
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1
12
10
0
4
3
15
2
17
3
12
6
23
12
14
3
13
1
24 1
3
18
17
2
4
23
19 20
4
20
2
25
8
22
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Critical Path
1/11
12/12
Every activity on the critical path must
begin on the earliest start date.
15/15
17/17
22/23
0/0
12/14
4/13
24
17/17
23/24
25/25
19/20
17/17
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Slack
1/11
10
1 12/12
Slack of activity
= (latest start)end - (earliest start)begin - (time estimate)
4 10
15/15
17/17
6 2
25/25
3 0
2 0
3
22/23
3
0/0 12 0
1 23/24
0
1 1
1
122 12/14
13
17/17
19/20
3
2 1
25 0
2
8
4 9
0
4/13
17/17
4 9
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Estimating the Time for an Activity
With experienced staff, estimating the actual time to carry out a
single task is usually fairly accurate, but ...
The little bits and pieces are underestimated
• The time from almost "done" to completely "done" is much longer
than anticipated. (There's just one thing to tidy up. I need to put
the comments into better shape. I really should get rid of that
patch.)
• The distractions are not planned for. (My system crashed and I
decided to upgrade the software. My child's school was closed
because of snow. I spent the day showing visitors around.)
Some things have to be done twice.
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Start-up Time
On a big project, the start-up time is typically three to six
months:
• Personnel have to complete previous projects (fatigue) or
be recruited.
• Hardware and software has to be acquired and installed.
• Staff have to learn new domain areas and software (slow
while learning).
• Clients may not be ready.
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Final Analysis with Critical Path
Method
Administrative computing department at Dartmouth used the
Critical Path Method for implementation phase of major
projects (plan developed after project was well-understood).
Experience: Elapsed time to complete projects was consistently
30% to 40% longer than predicted by model.
Analysis:
• Some tasks not anticipated (incomplete understanding)
• Some tasks had to be redone (change of requirements,
technical changes)
• Key personnel on many activities (schedule conflicts)
• System ZZZ (non-billable hours)
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Adding Resources to Activity Graph or
Gantt Chart
Each activity is labeled with resources, e.g.,
Number of people (e.g., 2 Java programmers)
Key personnel (e.g., chief system architect)
Equipment (e.g., 3 servers with specified software)
Facilities (e.g., video conference center)
Each resource is labeled with availability, e.g.,
Hiring and training
Vacations
Equipment availability
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Using Critical Path Method for
Resources
Assume every activity begins at earliest start date:
In each time period, calculate:
resources required
resources available
Identify shortage / surplus resources
Adjust schedule
acquire extra staff (e.g., consultants)
rearrange schedule (e.g., change vacations)
change order of carrying out activities
The earlier that a problem is known, the easier it is to fix.
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Key Personnel:
The Mythical Man Month
In computing, not all people are equal
• The best are at least 5 times more productive.
• Some tasks are too difficult for everybody.
Adding more people adds communications complexity
• Some activities need a single mind.
• Sometimes, the elapsed time for an activity can not be
shortened.
What happens to the project if a key person is sick or quits?
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Open University Example:
Flexibility
Schedule: Dates for broadcasting TV and radio programs are
fixed. Printing and mailings can be accelerated if overtime is
used.
Functionality: The course team can decide what goes into the
components of the course.
Resources: The size of the course team can be increased
slightly.
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Value of Scheduling Tools
Planning discipline
• Identify all activities and inter-relationship
• Provide schedule for each resource (identify clashes)
• Early warning of difficulties (e.g., timing of equipment
purchase)
Routine updating of schedule
• Focus on key milestones
• Visibility for management
Weekly staff meeting -- What did we expect to accomplish?
What did we accomplish? What is expected for next week?
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The Project Manager
•
•
•
•
Create and maintain the schedule.
Track progress against schedule.
Keep some slack in the schedule (minimize risk).
Continually make adjustments:
Start activities before previous activity complete
Sub-contract activities
Renegotiate deliverables
• Keep senior management informed (visibility).
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Updating the Plan
A PROJECT PLAN IS USELESS IS IT IS NOT UPDATED:
• Whenever changes occur
• On a regular schedule (weekly or monthly)
The project manager needs the support of the head of the
development team and the confidence of the team members.
A realistic, current project plan is an essential part of visibility.
*
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