Lecture 4 : Software Process Management

Lecture 4:Software Process Management Dr Valentina Plekhanova University of Sunderland, UK http://www.cet.sunderland.ac.uk/~cs0vpl/SE-Com185.htm

Process Models … • Existing process modelsrepresent various projects goal(s) and this defines an ordering of project (tasks) activities. Valentina Plekhanova

Project Management • In contrast with software process models,project managementdeals with resources. • Moreover, it is used as a means to provide planning, organisation, direction and control of resources in order to meet an organisation’s objectives by a specific date and within a well-defined budget. • Project management involves the application of limited resources to the completion of tasks in the most effective and efficient manner. Valentina Plekhanova

Project Scheduling • A pivotal problem of project management is to find the best trade-offs among resources. • Support for the co-ordination of people, tasks, equipment, products, time and money is provided by project management scheduling. Valentina Plekhanova

Planning Phase: Estimating Duration & Cost • … ??? Duration… • Another important part is estimating the duration of the project. • However, in estimating these issues a large number of variables are involved, principally the human factor. Valentina Plekhanova

Cost Estimation • An accurate cost estimation is an integral part of any software project management plan. • A number of approaches can be used for cost estimation. These include: • Expert judgement by analogy: consultation between a number of experts to devise a cost structure based on previous similar projects he/she has worked on Bottom-up approach: breaking the target product into smaller units. Valentina Plekhanova

COCOMO • A number of algorithmic models have been devised. • The major one is Boehm’s Constructive Cost Model (COCOMO). Valentina Plekhanova

Training Requirements • Staff must be trained in new software development methods; operating systems, documentation preparation and hardware. • A training plan must then be incorporated into the SPMP. Valentina Plekhanova

Project Management:Metrics • Metrics can be used to measure the size of a product. • These include: • Lines of code (?!) • Thousand delivered source instructions (?!) • …? Valentina Plekhanova

Project Management:Metrics • However, the above metrics are dependent on the language used, whether executable or comments should be counted and not all source code is delivered to the client. Valentina Plekhanova

Project Management Tools • Well-known management tools are Critical Path Method (CPM) and Program Evaluation Report technique (PERT). • These tools are used to assist in the planning phase. • This can determine which activities are critical and may delay the project if not completed on time. Valentina Plekhanova

Basic Project Management Scheduling Techniques • There are different types of schedules. • Some of the basic ones are Gantt charts, CPM and PERT types. Valentina Plekhanova

Gantt Charts • Gantt charts is the typical method of scheduling construction projects. • The primary limitation of this technique, as is outlined in literature is its inability to direct attention to the interrelationships and interdependencies among the activities. Valentina Plekhanova

Gantt Charts Valentina Plekhanova

Critical Path Method • CPM typeis based on theCritical Path Method. • This type looks for the schedule with minimum cost in a definite period of time in the case where the cost is associated with each activity. • Time is a resource. • The resource allocation problem is to allocate time among project tasks. Valentina Plekhanova

Critical Path Method …& SE ..??! 10 E B 10 10 5 20 5 V A D 15 15 C 10 10 F ABEV 30 ACDFV50 ACDV 30 ADFV 45 ADEV 35 Valentina Plekhanova

Program Evaluation Review Techniques • PERT type, which is based on the Program Evaluation Review Techniques, looks for the schedule, which minimises the objective function such as project time (total elapsed time). • That is, it determines the start and completion times of each activity. Valentina Plekhanova

CPM & PERT • Both techniques CPM and PERT use network methods to assist in project management and to overcome the interrelationship limitation in Gantt charts. • Both these techniques CPM&PERT identify aproject critical path whose activities could not be delayed, and also indicate slack activities that could be somewhat delayed without lengthening the project completion time. Valentina Plekhanova

CPM & PERT: Difference • CPM and PERT have the underlying difference. From its origin viewpoint, the CPMtechnique was developed for constructionprojects, while PERT was elaborated for research and development projects. Valentina Plekhanova

CPM • In the construction industry, prior experience with similar projects can be used to predict time estimates for projects within a relatively tight range. • In the CPM method the expected activity time is a single point estimate that assumes certainty: each activity is considered of exact fixed length. That is, CPM assumes that time is predictable or deterministic. Valentina Plekhanova

PERT • However, with researchanddevelopment projects, a great deal of uncertainty is associated with time estimates because no previous similar experience exists and precise time estimates are not available. • PERT assumes the time estimate for an activity lies within the range of earliest time and latest time. Valentina Plekhanova

PERT [Gray, 1981] • PERT usesthree time estimates(optimistic, most likely, and pessimistic) to compute the average or expected time. • PERT offers a way of dealing with random variation and considers each activity stochasticin that variability is allowed in each activity. Valentina Plekhanova

PERT [Plekhanova, 1998; Plekhanova 2000] • It should be pointed out, that PERT was developed forresearchanddevelopment projects,which consist ofcognitive tasks. • However, PERT is not concerned with the specific character of cognitive tasks. Valentina Plekhanova

CPM & PERT • PERT&CPM have been found to be useful in project management to provide efficient resource scheduling. In particular, PERT&CPM identify the critical jobs, which control the project completion date. • Moreover, the application of these tools reduces the degree of scheduling errors and, hence, increases the cost savings. Valentina Plekhanova

CPM & PERT • However, as mentioned in project management literature, the actual savings derived from using PERT&CPM methods are difficult to identify and measure precisely. Valentina Plekhanova

Note that [Plekhanova 2000]… • existing project management scheduling tools are concerned with a problem of resource availability and utilisation, not with capability and compatibility of project resources. • There is, therefore, an assumption that the quality of project resources does not have an impact on project scheduling and task performance. Valentina Plekhanova

Paradox !!!! [Plekhanova 2000] • We have a paradoxical situation, in that contemporary project management approaches (both mathematical and heuristic based) cannot be sufficiently employed in complex situations [Gray, 1981] and, yet, they are used for complex situations in practice. Valentina Plekhanova

Management is a human activity ! • It is important to notice that although there are many project management (scheduling) tools, use of them does not guarantee success. • Management is a human activity and project success depends on the competence of management. Valentina Plekhanova

Lecture 4 : Software Process Management