1. Software project management (intro)
Scheduling

2. Introduction
In addition to the effort forecast for a project, a detailed plan for the project must include a schedule indicating the start and completion times, which will enable us:
Ensure that appropriate resources will be available precisely when required
Avoid different activities competing for the same resources at the same time
Produce a detailed schedule showing which staff carry out each activity
Produce detailed plan against which actual achievent may be measured
Produce a timed cash flow forecast
Re-plan the project during its life to correct drift from the target

3. Objectives of activity planning
Feasibility assessment
Resource allocation
Detailed costing
Motivation
Co-ordination

4. When to plan?
Throughout the project, monitoring and re-planning must continue to correct any drift that might prevent meeting the time or cost targets
Planning is an ongoing process of refinement, each iteration becoming more detailed and more accurate than the last
Purpose of project planning:
During the feasibility study and project start up
Estimates timescales and the risks
Beyond feasibility study:
The production of activity plans to ensure resource availability and cash flow control

5. Project schedules
Creating project schedules comprises four main stages:
Decide what activities need to be carried out and in what order they are to be done
Construct an ideal activity plan
That is, no constraint on resources
Allocate resource
Produce schedule

6. Project and activities -- What are they?
A project is composed of a number of inter-related activities
A project may start when at least one of its activities is ready to start
A project will be completed when all of the activities have been completed
An activity must have a clearly defined start and end-point
Resource requirement of an activity must be forecast-able
Duration of an activity must be forecast-able
Some activities might require that others are completed before they begin

7. Identifying activities
Three approaches:
The activity based approach
Product-based approach
Hybrid approach

8. Activity based approach
Creating a list of all involved activities in the project
Work Breakdown Structure (WBS)
The WBS can be conceived as a tree,
with the project as the root node,
major components of the project as the main branches, and
tasks/subtasks branch off from these.
A WBS may be a diagram or a text list.

9. Activity based approach (2)
WBS Example
Project
Analyze
Design
Project
Data design
Process design
Physical design
Relational data analysis
Logical data analysis

10. Activity based approach (3)
Example of Textual WBS
33.01 MOBILIZATION AND PREPARATORY WORK
MOBILIZATION OF CONSTRUCTION EQUIP. AND FACILITIES
MOBILIZATION OF PERSONNEL
PRECONSTRUCTION SUBMITTALS/IMPLEMENTATION PLANS
Erosion Control Plan
Environmental Protection Plan
(etc)
Construction Quality Control Plan
SETUP/CONSTRUCT TEMPORARY FACILITIES
CONSTRUCT TEMPORARY UTILITIES
33.02 MONITORING, SAMPLING, TESTING, AND ANALYSIS
AIR MONITORING AND SAMPLING
33.03 SITE WORK
ROADS/PARKING/CURBS/WALK
Aggregate Surfacing
(Source: US Army Corps of Engineers)

11. Product Based Approach
Producing
Product Breakdown Structure (PBS)
identifies all the products
Product Flow Diagram (PFD)
shows how products interrelate

12. Product Based Approach (2)
PBS Example
Requirement Specification
Data catalogue
Requirement catalogue
Processing specification
Attribute/Data Item
description
Grouped domain
description
User Role/
Function Matrix
Function
definition
Logical data model
Entity life
History
I/O
Structure
Enquiry Access Path
Elementary Process Description

13. Product Based Approach (2)
The Product Flow Diagram shows which products must be complete before the next can be produced
Most items in the diagram are things the customer needs,
eg. design documentation, software, manuals
indicated by boxes
Some items are intermediate products, needed only to help produce other products,
eg. first cut database design
Some items will exist already,
eg. feasibility study report, terms of reference
indicated by ellipses (ovals)
Arrows indicate that one product is required in order to produce the next

14. Product Based Approach (3)
PFD Example

15. Hybrid Approach
Create a WBS that is based upon the project’s products, which is in turn based on a simple list of deliverables and a set of activities for each deliverable
Project
Installed System
Software component
User manual
Training course
Analyze req.
review req.
Outline design
Outline design
Integrate system
Code software
Test system
Test software

16. Sequencing and Scheduling Activities
To sequence the task according to their logical relationship, and
To schedule them taking into account resources and other factors

17. Events versus activities
Event = a point in time
has no duration
e.g the start or end of an activity
Activity = a task or an action with a recognizable start and finish and a duration
events
Prepare breakfast
Eat breakfast
activities

18. Start and finish times Activity ‘write report software’
Latest
finish
Earliest start
activity
Latest start
Earliest finish
Activity ‘write report software’
Earliest start (ES)
Earliest finish (EF) = ES + duration
Latest finish (LF) = latest task can be completed without affecting project end Latest start = LF - duration

19. Example earliest start = day 5 latest finish = day 30
duration = 10 days
earliest finish = ?
latest start = ?
Float = LF - ES - duration
What is it in this case?

20. Float Float = Latest finish - Earliest start - Duration FLOAT LF ES
activity
Latest start

21. Critical path Note the path through network with zero floats
Critical path: any delay in an activity on this path will delay whole project
Can there be more than one critical path?
Can there be no critical path?
Sub-critical paths