CS3773 Software Engineering Lecture 8 Software Planning and Estimation

UTSA CS Software Management  Software engineering is a managed process – People management – Software cost estimation – Quality management – Configuration management  Software management activities may include – Proposal writing – Software planning – Project monitoring – Personnel selection and evaluation

UTSA CS Software Planning  Effective software management depends on thoroughly planning the progress of the project  Project planning identifies the activities, milestones, and deliverables produced by a project  Project plan guides the development towards the project goals  In planning, cost estimation is an important task, which is concerned with estimating the resources required to accomplish the project plan

UTSA CS Project Plan  Project plan shall include the following sections – Introduction – Project organization – Risk analysis – Hardware and software resource requirements – Work breakdown – Project schedule – Monitoring and reporting mechanism  Project plan is revised during project development

UTSA CS Milestones and Deliverables  A milestone is a recognizable end-point of a software process activity – Deliverables are milestones Requirements specification Architectural design Program – Internal project results that are used by the project manager to check project progress are milestones  Software process must be broken down into basic activities with associated outputs to establish milestones

UTSA CS Project Scheduling  Project scheduling separates the total work involved in a project into separate activities and judging the time required to complete them  Project scheduling organizes all the activities into a coherent order – Some of the activities can be carried out in parallel – Some of the activities must be organized in a sequential manner – Project activities shall last lat least a week  Project schedules are usually represented as a set of charts or diagrams

UTSA CS Mechanics of Scheduling  We follow the three steps to produce a project schedule – Decomposing activities into subtasks and estimating the durations - produce an estimation table – Identifying dependencies on subtasks – produce a priority graph – Assigning subtasks and analyzing resulting schedule – produce a critical path diagram  Project schedule charts or diagrams show work breakdowns, activities dependencies, and staff allocations

UTSA CS Estimation Table Task NamesDuration (days)Accumulated Duration * IT133 IT258 IT3412 IT4416 IT5723 IT6225 * We assume that the project is done by a single developer

UTSA CS Priority Graph

UTSA CS Critical Path Method (CPM)  CPM take as input – Estimation table – Priority graph – An assignment of each task to a programmer – An ordering on the tasks assigned to each programmer  It computes – Earliest start time of each task – Earliest completion time for all tasks – Slack time, the amount of time starting on a task can be delayed without affecting the earliest completion date

UTSA CS CPM: Notational Convention for Tasks

UTSA CS CPM: Ordering of Constraints

UTSA CS CPM Example

UTSA CS CPM Example

UTSA CS CPM Example

UTSA CS CPM Example

UTSA CS CPM Example

UTSA CS CPM Example

UTSA CS Gantt Charts

UTSA CS Reading Assignments  Sommerville’s Book, 8 th edition – Chapter 5, “Project Management”  Sommerville’s Book, 9 th edition – Chapter 22, “Project Management” – Chapter 23, “Project Planning”