©ian sommerville 2000software engineering, 6th edition. chapter 4 slide 1 objectives l to introduce...
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©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 1
Objectives
To introduce software project management and to describe its distinctive characteristics
To discuss project planning and the planning process
To show how graphical schedule representations are used by project management
To discuss the notion of risks and the risk management process
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 2
Topics covered
Management activities Project planning Project scheduling Risk management
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 3
Concerned with activities involved in ensuring that software is delivered on time and on schedule and in accordance with the requirements of the organisations developing and procuring the software
Project management is needed because software development is always subject to budget and schedule constraints that are set by the organisation developing the software
Software project management
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 4
The product is intangible The product is uniquely flexible Software engineering is not recognized as an
engineering discipline with the sane status as mechanical, electrical engineering, etc.
The software development process is not standardised
Many software projects are 'one-off' projects
Software management distinctions
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 5
Proposal writing Project planning and scheduling Project costing Project monitoring and reviews Personnel selection and evaluation Report writing and presentations
Management activities
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 6
These activities are not peculiar to software management
Many techniques of engineering project management are equally applicable to software project management
Technically complex engineering systems tend to suffer from the same problems as software systems
Management commonalities
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 7
Project staffing
May not be possible to appoint the ideal people to work on a project• Project budget may not allow for the use of highly-paid staff• Staff with the appropriate experience may not be available• An organisation may wish to develop employee skills on a
software project
Managers have to work within these constraints especially when (as is currently the case) there is an international shortage of skilled IT staff
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 8
Project planning
Probably the most time-consuming project management activity
Continuous activity from initial concept through to system delivery. Plans must be regularly revised as new information becomes available
Various different types of plan may be developed to support the main software project plan that is concerned with schedule and budget
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 9
Types of project plan
Plan DescriptionQuality plan Describes the quality procedures and
standards that will be used in a project.Validation plan Describes the approach, resources and
schedule used for system validation. Configurationmanagement plan
Describes the configuration managementprocedures and structures to be used.
Maintenance plan Predicts the maintenance requirements ofthe system, maintenance costs and effortrequired.
Staff development plan. Describes how the skills and experience ofthe project team members will bedeveloped.
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 10
Project planning processEstablish the project constraints Make initial assessments of the project parameters Define project milestones and deliverableswhile project has not been completed or cancelled loop
Draw up project scheduleInitiate activities according to schedule
Wait ( for a while ) Review project progress Revise estimates of project parameters Update the project schedule Re-negotiate project constraints and deliverables if ( problems arise ) then Initiate technical review and possible revision end ifend loop
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 11
Project plan structure
Introduction Project organisation Risk analysis Hardware and software resource requirements Work breakdown Project schedule Monitoring and reporting mechanisms
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 12
Activity organization
Activities in a project should be organised to produce tangible outputs for management to judge progress
Milestones are the end-point of a process activity Deliverables are project results delivered to
customers The waterfall process allows for the
straightforward definition of progress milestones
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 13
Milestones in the RE process
Evaluationreport
Prototypedevelopment
Requirementsdefinition
Requirementsanalysis
Feasibilityreport
Feasibilitystudy
Architecturaldesign
Designstudy
Requirementsspecification
Requirementsspecification
ACTIVITIES
MILESTONES
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 14
Project scheduling Split project into tasks and estimate time and
resources required to complete each task Organize tasks concurrently to make optimal
use of workforce Minimize task dependencies to avoid delays
caused by one task waiting for another to complete
Dependent on project managers intuition and experience
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 15
The project scheduling process
Estimate resourcesfor activities
Identify activitydependencies
Identifyactivities
Allocate peopleto activities
Create projectcharts
Softwarerequirements
Activity chartsand bar charts
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 16
Scheduling problems
Estimating the difficulty of problems and hence the cost of developing a solution is hard
Productivity is not proportional to the number of people working on a task
Adding people to a late project makes it later because of communication overheads
The unexpected always happens. Always allow contingency in planning
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 17
Bar charts and activity networks
Graphical notations used to illustrate the project schedule
Show project breakdown into tasks. Tasks should not be too small. They should take about a week or two
Activity charts show task dependencies and the the critical path
Bar charts show schedule against calendar time
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 18
Task durations and dependencies
Task Duration (days) DependenciesT1 8T2 15T3 15 T1 (M1)T4 10T5 10 T2, T4 (M2)T6 5 T1, T2 (M3)T7 20 T1 (M1)T8 25 T4 (M5)T9 15 T3, T6 (M4)T10 15 T5, T7 (M7)T11 7 T9 (M6)T12 10 T11 (M8)
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 19
Activity network
start
T2
M3T6
Finish
T10
M7T5
T7
M2T4
M5
T8
4/7/99
8 days
14/7/99 15 days
4/8/99
15 days
25/8/99
7 days
5/9/99
10 days
19/9/99
15 days
11/8/99
25 days
10 days
20 days
5 days25/7/99
15 days
25/7/99
18/7/99
10 days
T1
M1 T3T9
M6
T11
M8
T12
M4
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 20
Activity timeline4/7 11/7 18/7 25/7 1/8 8/8 15/8 22/8 29/8 5/9 12/9 19/9
T4
T1T2
M1
T7T3
M5T8
M3
M2T6
T5M4
T9
M7T10
M6
T11M8
T12
Start
Finish
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 21
Staff allocation4/7 11/7 18/7 25/ 1/8 8/8 15/8 22/8 29/8 5/9 12/9 19/9
T4
T8 T11
T12
T1
T3
T9
T2
T6 T10
T7
T5
Fred
Jane
Anne
Mary
Jim
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 22
Risk management
Risk management is concerned with identifying risks and drawing up plans to minimise their effect on a project.
A risk is a probability that some adverse circumstance will occur. • Project risks affect schedule or resources• Product risks affect the quality or performance of the software
being developed• Business risks affect the organisation developing or procuring
the software
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 23
Software risksRisk Risk type DescriptionStaff turnover Project Experienced staff will leave the
project before it is finished.Management change Project There will be a change of
organisational management withdifferent priorities.
Hardware unavailability Project Hardware which is essential for theproject will not be delivered onschedule.
Requirements change Project andproduct
There will be a larger number ofchanges to the requirements thananticipated.
Specification delays Project andproduct
Specifications of essential interfacesare not available on schedule
Size underestimate Project andproduct
The size of the system has beenunderestimated.
CASE tool under-performance
Product CASE tools which support theproject do not perform as anticipated
Technology change Business The underlying technology on whichthe system is built is superseded bynew technology.
Product competition Business A competitive product is marketedbefore the system is completed.
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 24
The risk management process
Risk identification• Identify project, product and business risks
Risk analysis• Assess the likelihood and consequences of these risks
Risk planning• Draw up plans to avoid or minimise the effects of the risk
Risk monitoring• Monitor the risks throughout the project
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 25
The risk management process
Risk avoidanceand contingency
plans
Risk planning
Prioritised risklist
Risk analysis
List of potentialrisks
Riskidentification
Riskassessment
Riskmonitoring
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 26
Risk identification
Technology risks People risks Organisational risks Requirements risks Estimation risks
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 27
Risks and risk typesRisk type Possible risksTechnology The database used in the system cannot process as
many transactions per second as expected.Software components which should be reused containdefects which limit their functionality.
People It is impossible to recruit staff with the skills required.Key staff are ill and unavailable at critical times.Required training for staff is not available.
Organisational The organisation is restructured so that differentmanagement are responsible for the project.Organisational financial problems force reductions in theproject budget.
Tools The code generated by CASE tools is inefficient.CASE tools cannot be integrated.
Requirements Changes to requirements which require major designrework are proposed.Customers fail to understand the impact of requirementschanges.
Estimation The time required to develop the software isunderestimated.The rate of defect repair is underestimated.The size of the software is underestimated.
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 28
Risk analysis
Assess probability and seriousness of each risk Probability may be very low, low, moderate, high
or very high Risk effects might be catastrophic, serious,
tolerable or insignificant
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 29
Risk analysisRisk Probability EffectsOrganisational financial problems forcereductions in the project budget.
Low Catastrophic
It is impossible to recruit staff with the skillsrequired for the project.
High Catastrophic
Key staff are ill at critical times in the project. Moderate SeriousSoftware components which should be reusedcontain defects which limit their functionality.
Moderate Serious
Changes to requirements which require majordesign rework are proposed.
Moderate Serious
The organisation is restructured so that differentmanagement are responsible for the project.
High Serious
The database used in the system cannot processas many transactions per second as expected.
Moderate Serious
The time required to develop the software isunderestimated.
High Serious
CASE tools cannot be integrated. High TolerableCustomers fail to understand the impact ofrequirements changes.
Moderate Tolerable
Required training for staff is not available. Moderate TolerableThe rate of defect repair is underestimated. Moderate TolerableThe size of the software is underestimated. High TolerableThe code generated by CASE tools is inefficient. Moderate Insignificant
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 30
Risk planning
Consider each risk and develop a strategy to manage that risk
Avoidance strategies• The probability that the risk will arise is reduced
Minimisation strategies• The impact of the risk on the project or product will be reduced
Contingency plans• If the risk arises, contingency plans are plans to deal with that
risk
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 31
Risk management strategies
Risk StrategyOrganisationalfinancial problems
Prepare a briefing document for senior management showing how the project ismaking a very important contribution to the goals of the business.
Recruitmentproblems
Alert customer of potential difficulties and the possibility of delays, investigatebuying-in components.
Staff illness Reorganise team so that there is more overlap of work and people thereforeunderstand each other’s jobs.
Defectivecomponents
Replace potentially defective components with bought-in components of knownreliability.
Requirementschanges
Derive traceability information to assess requirements change impact, maximiseinformation hiding in the design.
Organisationalrestructuring
Prepare a briefing document for senior management showing how the project ismaking a very important contribution to the goals of the business.
Databaseperformance
Investigate the possibility of buying a higher-performance database.
Underestimateddevelopment time
Investigate buying in components, investigate use of a program generator.
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 32
Risk monitoring
Assess each identified risks regularly to decide whether or not it is becoming less or more probable
Also assess whether the effects of the risk have changed
Each key risk should be discussed at management progress meetings
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 33
Risk factors
Risk type Potential indicatorsTechnology Late delivery of hardware or support software, many reported
technology problemsPeople Poor staff morale, poor relationships amongst team member,
job availabilityOrganisational organisational gossip, lack of action by senior managementTools reluctance by team members to use tools, complaints about
CASE tools, demands for higher-powered workstationsRequirements many requirements change requests, customer complaintsEstimation failure to meet agreed schedule, failure to clear reported
defects
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 34
Key points
Good project management is essential for project success
The intangible nature of software causes problems for management
Managers have diverse roles but their most significant activities are planning, estimating and scheduling
Planning and estimating are iterative processes which continue throughout the course of a project
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 35
A project milestone is a predictable state where some formal report of progress is presented to management.
Risks may be project risks, product risks or business risks
Risk management is concerned with identifying risks which may affect the project and planning to ensure that these risks do not develop into major threats
Key points
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 36
Milestones
Projects are managed by deliverables. Each team must schedule its effort so as to present the required deliverable at the milestone.1. Prototype Presentation 9/182. Functional Specification document 10/23. Design Presentation 10/94. Design Specification document 10/165. Testing Presentation 10/306. Users Manual 11/67. Alpha demonstration 11/138. Test Plan Document & Alpha report 11/209. Systems Manual 12/210. Beta Presentation 12/411. Legacy Document 12/9
©Ian Sommerville 2000 Software Engineering, 6th edition. Chapter 4 Slide 37
Effort is Allocated and Logged
Tasks required for each milestones must be identified and evaluated for difficulty and duration.
Tasks are divided among team members with deadlines.
Each person logs time expended on task and notes any ambiguity or incompleteness in accomplishment.
Clerk maintains schedule, consolidates logs, and warns about potential delays (risks).