Software Engineering

Transcription

1 Software Engineering Project Management 1 Objectives To explain the main tasks undertaken by project managers 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 2

2 Topics covered Management activities Project planning Project scheduling Risk management 3 Software project management 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 4

3 Software management distinctions The product is intangible Other engineering disciplines can see the product being developed (e.g. civil engineering) The product is uniquely flexible. Software engineering is not recognized as an engineering discipline with the same status as mechanical, electrical engineering, etc. The software development process is not standardised New compared to other engineering disciplines Software process varies Many software projects are 'one-off' projects Software systems varies dramatically 5 Management activities Proposal writing: Describes the objective of the project Usually includes costs and schedule estimates Justifies why it should be awarded to this contractor Critical task It is a skill acquired by practice and experience Project planning and scheduling: Identify activities, milestones and deliverables Resource allocation Project costing: Cost and resource requirements estimation is related activities 6

4 Management activities Project monitoring and reviews: Keep track of the progress of the project and compare actual progress and planned progress and costs Manager can form a picture of what is going on through informal discussion with staff, not waiting until review or report Review: overall progress and technical developments checking if goals and progress are still aligned 7 Management activities Personnel selection and evaluation: Ideally, staff with most appropriate experience, but often managers have to settle for less-than-ideal project team. Reasons: The project budged may not cover the use of highly paid staff Staff with the appropriate experience may not be available within organisation or externally Organisation may wish to develop the skills of its employees Managers have to work within these constraints especially when there are shortages of trained staff 8

5 Management activities Report writing and presentations: Project manager responsibility reporting to user and customer Have to write concise, coherent documents that abstract critical information from detailed project reports Manager has to communicate effectively both oral and in writing 9 Management commonalities 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 10

6 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 Plan that should be used as driver for the project Next slide shows other types of project plans beside or integrated to the software development plan 11 Types of project plan Plan Quality plan Validation plan Configuration management plan Maintenance plan Staff plan. development Description Describes the quality procedures and standards that will be used in a project. See Chapter 27. Describes the approach, resources and schedule used for system validation. See Chapter 22. Describes the configuration management procedures and structures to be used. See Chapter 29. Predicts the maintenance requirements of the system, maintenance costs and effort required. See Chapter 21. Describes how the skills and experience of the project team members will be developed. See Chapter

7 Project Planning The project plan process is an iterative process, only completed when project is completed Goals of the business are important factors considered when formulating a project plan Assess of constraints (required delivery date, staff available, overall budge, etc.) Estimate project parameters (structure, size, distribution of functions) Define milestones and deliverables When more information available, review original assumptions If problems arise, initiate technical review in order to find alternatives Assumptions and scheduling should be pessimistic See project plan process next slide 13 Project planning process Establish the project constraints Make initial assessments of the project parameters Define project milestones and deliverables while project has not been completed or cancelled loop Draw up project schedule Initiate 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 if end loop 14

8 The project plan The project plan sets out: The resources available to the project; The work breakdown; A schedule for the work. 15 Project plan structure Introduction Describes objectives and constraints Project organisation Describes how development team is organised and their roles Risk analysis Describes possible project risks, likelihood, risk reduction strategies Hardware and software resource requirements What to buy and estimates Work breakdown Activities, milestones and deliverables Project schedule Dependencies between activities, estimated time and staff allocation Monitoring and reporting mechanisms What managements reports to produce, when and mechanism used 16

9 Activity organisation Activities in a project should be organised to produce tangible outputs for management to judge progress Task an activity with clear start and end Milestones are the end-point of a process activity Formal output (e.g. report) Represent the end of a distinct, logical stage in the project Avoid indefinite milestones (e.g. coding 80% complete, this is uncertain, cannot be checked) Deliverables are project results delivered to customers Usually are milestones, but not the contrary The waterfall process allows for the straightforward definition of progress milestones Establishing milestones need to break the software process into basic activities with associated outputs 17 Milestones in a requirements process 18

10 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 19 The project scheduling process 20

11 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 21 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 at least one week or two. It should have a maximum time, for example, around 8 to 10 weeks. Activity charts show task dependencies and the critical path Bar charts show schedule against calendar time 22

12 Task durations and dependencies Activity Duration (days) Dependencies T1 8 T2 15 T3 15 T1 (M1) T4 10 T5 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) 23 Activity network 24

13 Activity network The activity chart shows the activities that can be carried out in parallel and the ones that must be executed in sequence (dependency) Activities are represented by rectangles Milestones and deliverables by rounded corners Dates are the starting dates It should be read from left to right and from top to bottom Managers use it to have an insight of activity dependencies and try to shorten time by reducing amount of time spent in waiting for activities to finish (when possible) 25 Activity network Key terms: Minimum time to finish the project can be estimated by the critical path (longest path) shown in bolded rectangles Overall schedule depends on critical path Slippage in activities of critical path causes project delays Other activities (not in the critical path) can have slippage to certain extend and not affecting overall schedule they have slack time Recurring task A task that repeats at regular time intervals, e.g. once a week, e.g. weekly report submission Summary task Tasks can be organised in a hierarchy of subtasks. The top task is known as a summary task, its duration and characteristics are made up of those of its subtasks 26

14 Activity timeline 27 Activity timeline Also called Gantt Chart, after its inventor Shaded part in activities show flexibility in completion Next slide show chart with resource (staff) allocation 28

15 Staff allocation 29 Monitoring/Reporting Metrics Weekly Reports/Weekly Meetings Customer Meetings Demo s [2] 30

16 Metrics Project scheduling and project budgeting is often based on prior project experiences and on various product and process measurements (metrics) collected in the past [3] Examples of metrics or measurements include: Number of lines of code Number of defects in code (in particular at defined points in development) Test cases completed and in what time frame Test cases passed Test cases failed Metrics on a live project are also used to assess progress of development against project plans [2] 31 Weekly Reports Reporting progress on tasks and milestones is a vital element of project management All stakeholders, including customers, investors, management, marketing, development need to have a view of the status of the project Often the initial reporting will be in the form of weekly or bi-weekly reports. These are at all levels: Designers to team leader Team leader s summary to manager Managers summary to senior management Etc. [2] 32

17 Weekly Reports (cont.) In addition to this weekly meetings take place at various levels, team, department, inter-department, release, customer etc. Weekly or often monthly meetings are used to report progress and also to make decisions on progress and if dates need to be changed or resources reallocated. Metrics are often used in these meetings. Demo s are used to show any relevant stakeholders progress and also to check with customers in particular, that the requirements are correct [2] 33 Change Management Any changes to or within a project must be managed Changes must not be allowed to manage the project [4] Changes can occur due to many reasons: Changes in external or internal project conditions (e.g. budget, resources, competition) Changes in user requirements Software defects (bugs) Etc. [2] 34

18 Change Management (cont.) Concentrating on requirements change: The advantage of using a formal process for change management is that all changes are treated the same and the requirements document is updated [1] Sommerville [1] states that there are three principal stages to a requirements change management process: Problem analysis and change specification Change analysis and costing Change implementation It is vital that the formal process takes place, even when the change is urgent [2] 35 Change Management (cont.) [1] [2] 36

19 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. 37 Software risks Risk Affects Description Staff turnover Project Experienced staff will leave the project before it is finished. Management change Project There will be a change of organisational management with different priorities. Hardware unavailability Project Hardware that is essential for the project will not be delivered on schedule. Requirements change Project and product There will be a larger number of changes to the requirements than anticipated. Specification delays Size underestimate CASE tool underperformance Project and product Project and product Product Specifications of essential interfaces are not available on schedule The size of the system has been underestimated. CASE tools which support the project do not perform as anticipated Technology change Business The underlying technology on which the system is built is superseded by new technology. Product competition Business A competitive product is marketed before the system is completed. 38

20 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; 39 The risk management process 40

21 Risk identification Technology risks Hardware and software technologies used to develop the system People risks Risks associate with the people involved in the development team Organisational risks Derive from the organisation environment where the software is being developed Requirements risks Changes to the customer requirements and the process of managing the changes Estimation risks From management estimates and resources required 41 Risks and risk types Risk type Technology People Organisational Tools Requirements Estimation Possible risks The database used in the system cannot process as many transactions per second as expected. Software components that should be reused contain defects that limit their functionality. It is impossible to recruit staff with the skills required. Key staff are ill and unava ilable at critical times. Required training for staff is not available. The organisation is restructured so that different management are responsible for the project. Organisational financial problems force reductions in the project budget. The code generated by CASE tools is inefficient. CASE tools cannot be integrated. Changes to requirements that require major design rework are proposed. Customers fail to understand the impact of requirements changes. The time required to develop the software is underestimated. The rate of defect repair is underestimated. The size of the software is underestimated. 42

22 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 Rely on analysts judgement and experience 43 Risk analysis (i) Risk Probability Effects Organisational financial problems force reductions in the project budget. It is impossible to recruit staff with the skills required for the project. Low High Catastrophic Catastrophic Key staff are ill at critical times in the project. Moderate Serious Software components that should be reused contain defects which limit their functionality. Changes to requirements that require major design rework are proposed. The organisation is restructured so that different management are responsible for the project. Moderate Moderate High Serious Serious Serious 44

23 Risk analysis (ii) Risk Probability Effects The database used in the system cannot process as many transactions per second as expec ted. The time required to develop the software is underestimated. Moderate High Serious Serious CASE tools cannot be integrated. High Tolerable Customers fail to understand the impact of requirements changes. Moderate Tolerable Required training for staff is not available. Moderate Tolerable The rate of defect repair is underestimated. Moderate Tolerable The size of the software is underestimated. High Tolerable The code generated by CASE tools is inefficient. Moderate Insignificant 45 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 46

24 Risk management strategies (i) Risk Organisational financial problems Recruitment problems Staff illness Defective components Strategy Prepare a briefing document for senior management showing how th e project is making a very important contribution to the goals of the business. Alert customer of potential difficulties and the possibility of delays, investigate buying-in components. Reorganise team so that there is more overlap of work and people therefore understand each other s jobs. Replace potentially defective components with boughtin components of known reliability. 47 Risk management strategies (ii) Risk Requirements changes Organisational restructuring Database performance Underestimated development time Strategy Derive traceability information to assess requirements change impact, maximise information hiding in the design. Prepare a briefing document for senior management showing how th e project is making a very important contribution to the goals of the business. Investigate the possibility of buying a higherperformance database. Investigate buying in components, investigate use of a program generator 48

25 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 49 Risk indicators Risk type Technology People Organisational Tools Requirements Estimation Potential indicators Late delivery of hardware or support software, many reported technology problems Poor staff morale, poor relationships amongst team member, job availability Organisational gossip, lack of action by senior management Reluctance by team members to use tools, complaints about CASE tools, demands for higher-powered workstations Many requirements change requests, customer complaints Failure to meet agreed schedule, failure to clear reported defects 50

26 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. 51 Key points A project milestone is a predictable state where a formal report of progress is presented to management. Project scheduling involves preparing various graphical representations showing project activities, their durations and staffing. 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 52

27 Recommended Reading Essential: Chapter 5 of Sommerville [1] 53 References [1] Software Engineering, Sommerville, 7 th Edition or later, Addison-Wesley, chapter 5 [2] ELE304 Rachel Jenkins, 2005 [3] Practical Software Engineering, Maciaszek & Liong, 2005, Pearson, pg. 187 [4] Practical Software Engineering, Maciaszek & Liong, 2005, Pearson, pg