软件工程实践者的研究方法chapter21.ppt

1These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Chapter 21nProject SchedulingSlide Set to accompanySoftware Engineering:A Practitioners Approach,7/e by Roger S.PressmanSlides copyright 1996,2001,2005,2009 by Roger S.PressmanFor non-profit educational use onlyMay be reproduced ONLY for student use at the university level when used in conjunction with Software Engineering:A Practitioners Approach,7/e.Any other reproduction or use is prohibited without the express written permission of the author.All copyright information MUST appear if these slides are posted on a website for student use.2These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Why Are Projects Late?nan unrealistic deadline established by someone outside the software development groupnchanging customer requirements that are not reflected in schedule changes;nan honest underestimate of the amount of effort and/or the number of resources that will be required to do the job;npredictable and/or unpredictable risks that were not considered when the project commenced;ntechnical difficulties that could not have been foreseen in advance;nhuman difficulties that could not have been foreseen in advance;nmiscommunication among project staff that results in delays;na failure by project management to recognize that the project is falling behind schedule and a lack of action to correct the problem3These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Scheduling Principlesncompartmentalizationdefine distinct tasksninterdependencyindicate task interrelationship neffort validationbe sure resources are availablendefined responsibilitiespeople must be assignedndefined outcomeseach task must have an outputndefined milestonesreview for quality4These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Effort and Delivery TimeEffort CostImpossible regiontdEdTmin=0.75TdtoEoEa=m(td4/ta4)development timeEa=effort in person-months td=nominal delivery time for schedule to=optimal development time(in terms of cost)ta=actual delivery time desired 5These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Effort Allocationn“front end”activitiesn customer communicationn analysisn designn review and modificationnconstruction activitiesn coding or code generationntesting and installationn unit,integrationn white-box,black boxn regression 6These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Defining Task Setsndetermine type of projectnassess the degree of rigor requirednidentify adaptation criterianselect appropriate software engineering tasks7These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Task Set Refinement1.1 Concept scoping determines the overall scope of the project.Task definition:Task 1.1 Concept Scoping 1.1.1Identify need,benefits and potential customers;1.1.2Define desired output/control and input events that drive the application;Begin Task 1.1.21.1.2.1FTR:Review written description of need FTR indicates that a formal technical review(Chapter 26)is to be conducted.1.1.2.2Derive a list of customer visible outputs/inputs1.1.2.3FTR:Review outputs/inputs with customer and revise as required;endtask Task 1.1.21.1.3Define the functionality/behavior for each major function;Begin Task 1.1.31.1.3.1FTR:Review output and input data objects derived in task 1.1.2;1.1.3.2Derive a model of functions/behaviors;1.1.3.3FTR:Review functions/behaviors with customer and revise as required;endtask Task 1.1.31.1.4Isolate those elements of the technology to be implemented in software;1.1.5Research availability of existing software;1.1.6Define technical feasibility;1.1.7Make quick estimate of size;1.1.8Create a Scope Definition;endTask definition:Task 1.1is refined to8These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Define a Task Network9These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Timeline ChartsTasksWeek 1Week 2Week 3Week 4Week nTask 1Task 2Task 3Task 4Task 5Task 6Task 7Task 8Task 9Task 10Task 11Task 1210These slides are designed to accompany Software Engineering:A Practitioners Approach,7/e(McGraw-Hill 2009).Slides copyright 2009 by Roger Pressman.Use Automated Tools toDerive a Timeline Chart11These slides are designed to accompany Software Engineer