Schedule: Scheduling Fundamentals

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Software Project Management (CS615)

LECTURE # 37

8. Scheduling

8.1

Understanding Schedule

Salient Features:

Fred Brooks, the well-known author of The Mythical-Man-Month [BRO95],

was once asked how software projects fall behind schedule. His response was

as simple as it was profound: "One day at a time."

The reality of a technical project (whether it involves building a hydroelectric

plant or developing an operating system) is that hundreds of small tasks must

occur to accomplish a larger goal.

Some of these tasks lie outside the mainstream and may be completed without

worry about impact on project completion date, Other tasks lie on the

"critical" path, these "critical" tasks fall behind schedule, the completion date

of the entire project is 'put into jeopardy,

The project manager's objective is to define all project tasks build a network

that depicts their interdependencies, identify the tasks that are critical within

the network, and then track their progress to ensure that delay is recognized

"one day at a time." To accomplish this, the manager must have a schedule

that has been defined at a degree of resolution that enables the manager to

monitor Progress and control the project.

Software project scheduling is an activity that distributes estimated effort

across the planned project duration by allocating the effort to specific software

engineering tasks.

It is important to note, however, that the schedule evolves over time. During

early stages of project planning, a macroscopic schedule is developed. This

type of schedule identifies all major software engineering activities and the

product functions to which they are applied.

As the project gets under way, each entry on the macroscopic schedule is

refined into a detailed schedule. Here specific software tasks (required to

accomplish an activity) are identified and scheduled.

Scheduling for software engineering projects can be viewed from two rather

different perspectives. In the first, an end-date for release of a computer-based

system has already (and irrevocably) been established.

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The software organization is constrained to distribute effort within the

prescribed time frame. The second view of software scheduling assumes that

rough chronological bounds have been discussed but the end-date is set by the

software engineering organization. Effort is distributed to make best use of

resources and an end-date is defined after careful analysis of the ware.

Unfortunately, the first situation is encountered far more frequently than the

second.

As a project manager, you need to assign durations to all activities and

monitor their progress.

You also need to plan the order in which the activities will be performed as

well as the start and end dates for each activity. In short, you need to create a

project schedule.

The plan includes not only the scheduling of development activities, but also

the scheduling of project resources, particularly people. To accomplish this,

the manager must have a schedule that has been defined at a degree of

resolution that enables the manager to monitor Progress and control the

project. The project schedule is one of the most important parts of the project

development plan.

The project schedule reflects the start dates and end dates for each activity in

the project. It also reflects the resources required to complete the activities. To

create a schedule, you can use project management tools.

To create a schedule, you can use project management tools, e.g.:

Gantt charts

Network-scheduling techniques

No matter how well the project schedule is prepared, that schedule is useless

unless it is adhered to. It is the project manager's responsibility to withstand

pressure and to assure that the project is developed in an orderly fashion,

according to the schedule. Whenever circumstances change, the project

schedule should then be updated to reflect the new situation.

ii.

Need for Project Scheduling

Software project have a tendency to get out of control because of the multiple

activities that need to be monitored, tracked, and controlled. When a project

goes out of control, the original deadlines, the budget, and the effort required

overshoot the initial estimates. This not only impacts the product, but also the

credibility of the development team.

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iii.

What Delays Software Projects

There are various reasons why a software project is delayed. Some of the

reasons are listed below:

The initial estimate of the effort and resources required to complete the

software project was incorrect. (An honest underestimate of the amount of

effort and/or the number of resources that will be required to do the job).

Changing customer requirements that are not reflected in schedule

changes.

Known risks were not mitigated. (Predictable and/or unpredictable risks

were not considered when the project commenced).

Technical difficulties surfaced during software product development.

(Technical difficulties could not have been foreseen in advance).

Human difficulties, such as interpersonal problems and team attitude,

became unmanageable. (Human difficulties that could not have been

foreseen in advance, e.g., Miscommunication among project staff resulting

in delays).

A failure by project management to recognize that the project is falling

behind schedule and a lack of action to correct the problem.

The initial deadline set for the project was unrealistic. (An unrealistic

deadline established by someone outside the software development group

and forced on managers and practitioners within the group).

Aggressive (read "unrealistic") deadlines are a fact of life in the software

business Sometimes such deadlines are demanded for reasons that are

legitimate, from the point of view of the person who sets the deadline. But

common sense says that legitimacy must also be perceived by the people

doing the work.

iv.

How to Prevent Delays

While most of the above reasons result in project delays, unrealistic deadlines

cause the maximum damage. Unrealistic deadlines are caused either by the

client wanting a quick delivery or the management wanting a return business

nom a client.

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However, unrealistic deadlines are the norm for software projects. You need

to resolve the conflict between an unrealistic deadline and the constraints of

the software development team.

As a project manager you need to balance the limited resources and the final

deliverable committed to the client. To do this, you can follow the points

listed below:

a) Study similar past projects for the method of dealing with similar

situations. Use the historical information to project time and effort

estimates for the current software project.

b) Use an incremental process model to create a schedule to deliver the

required functional module of the software product.

c) Present the schedule created on the basis of past projects to the client.

Explain the projected delays and the reasons for the same.

d) Present the incremental model as a strategy for developing the software

product.

All the strategies have their advantages and disadvantages. If the schedule

created using inputs from the past project does not help meet the deadline, you

can use the incremental model. In the incremental model, the strategy is to

deliver each module as and when it is completed. However, historical trends

show that clients opt for either strategy if provided reasonable time and effort

estimates.

8.2

Scheduling Fundamentals

Scheduling Basics

Only a small percentage of all the activities in a software project have a direct

impact on the on-time completion of the software project. Therefore, you need

to identify the activities that are critical to the completion of the project. In

addition, you ensure that all inputs are available to complete the critical

activities. This is where a software project schedule comes into the picture.

The goal of a software project schedule is to determine the duration of the

software project and the phases within the project. A software project

schedule enables you to distribute the estimated effort to be spent in

performing the critical activities.

There are a few basic principles that determine how a software project

schedule is created. To create a project schedule, first you group similar

activities together. Then, you determine the dependencies of the different

activities. Next, you allocate the estimated time and resources to each activity.

Finally, you define the roles and responsibilities and the output and validation

criteria.

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Some of the guidelines for creating a software project schedule are discussed

below:

Classification

Interdependence

Time and effort allocation

Validation criteria

Defined responsibilities and outputs

a) Classification

While managing a software project, you need to group similar tasks and

activities so that they are completed successfully. The primary tools used to

group similar tasks are the WBS and decomposition technique. Using these

tools, you can divide a software project into different phases. The phases can

be further subdivided into activities. The software project schedule is prepared

according to the arrangement of the phases.

b) Interdependence

As you have seen, a software project is composed of multiple phases and each

phase is composed of multiple activities. Although each activity is treated

separately, it is linked to other activities. As a project manager, you determine

the interdependence and sequence of activities. For example, some activities

can be completed without any inputs from other activities, whereas other

activities cannot start unless a preceding activity is completed.

c) Time and Effort Allocation

Each activity in a software project needs a certain amount of time and effort

for completion. To manage the project, you assign start and end dates to each

activity. You also need to allocate appropriate effort to each activity. Most

software projects operate with time and effort constraints. Therefore,

managing within the available resources is very important for a software

project manager.

d) Validation Criteria

You also determine the validation criteria for time and effort allocation in a

software project. Determining the validation criteria allows you to ensure that

the optimal level of resources is available for a particular activity. Suppose 5

people are assigned to an activity that requires an effort of 3.5 person days.

This means resources allocated are more than the actual requirement.

e) Defined Responsibilities and outputs

As a software project manager, you assign roles and responsibilities to all

people assigned to a software project. This defines the hierarchy in the

development team. You also define the outputs from each activity. This helps

in identifying the results expected at the end of every activity. Next, you link

the roles to the outputs. When each role is linked to the expected results, you

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can track each person's effort and the progress of each activity towards

closure.

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