Software Engineering Management

Lecture 1

The Software Process

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Software Process

Fundamental Assumption:

Good processes lead to good software

Good processes reduce risk

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Risk Management

What can go wrong in a software project?

How can the risk be reduced?

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The Software Process (Simplified)

Requirements

Operation andMaintenanceImplementation

Design

Feasibility andPlanning

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The Waterfall Model

RequirementsDefinition

System andSoftware design

Programmingand Unit Testing

Integration andSystem Testing

Operation andMaintenance

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Requirements Analysis and Definition

The system's services, constraints and goals are established by consultation with system users. They are then defined in a manner that is understandable by both users and development staff.

This phase can be divided into:

Feasibility study (often carried out separately)

Requirements analysis

Requirements definition

Requirements specification

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System and Software Design

System design: Partition the requirements to hardware or software systems. Establishes an overall system architecture

Software design: Represent the software system functions in a form that can be transformed into one or more executable programs

Unified Modeling Language (UML)

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Programming and Unit Testing

The software design is realized as a set of programs or program units. (Written specifically, acquired from elsewhere, or modified.)

Individual components are tested against specifications.

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Integration and System Testing

The individual program units are:

integrated and tested as a complete system

tested against the requirements as specified

delivered to the client

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Operation and Maintenance

Operation: The system is put into practical use.

Maintenance: Errors and problems are identified and fixed.

Evolution: The system evolves over time as requirements change, to add new functions or adapt the technical environment.

Phase out: The system is withdrawn from service.

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Discussion of the Waterfall Model

Advantages:

Process visibility Dependence on individuals Quality control Cost control

Disadvantages:

Each stage in the process reveals new understanding of the previous stages, that requires the earlier stages to be revised.

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Feedback in the Waterfall Model

RequirementsDefinition

System andSoftware design

Programmingand Unit Testing

Integration andSystem Testing

Operation andMaintenance

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Iterative Refinement(Evolutionary Development)

Concept: Initial implementation for user comment, followed by refinement until system is complete.

Vaporware: user interface mock-up

Throw-away software components

Dummy modules

Rapid prototyping

Successive refinement

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Iterative Refinement

Requirements

DesignImplementation

(prototype)

Evaluation

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Iterative Refinement

OutlineDescription

ConcurrentActivities

Requirements

Design

Implementation

InitialVersion

IntermediateVersions

FinalVersion

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Iterative Refinement & Software Process

OutlineDescription

ConcurrentActivities

Requirements

Design

Implementation FinalVersion

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Observations about Software Processes

Completed projects should look like the Waterfall Modelbut ... the development process is always partly evolutionary.

Risk is lowered by:

Prototyping key components

Dividing into phases

Following a visible software process

Making use of reusable components

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Feasibility Study

Before beginning a project, a short, low-cost study to identify

• Client

• Scope

• Potential benefits

• Resources needed:

staff, time, equipment, etc.

• Potential obstacles

Where are the risks? How can they be minimized?

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Feasibility Study

A feasibility study leads to a decision:

go aheaddo not go aheadthink again

In production projects, the feasibility study often leads to a budget request.

In research, a feasibility study is often in the form of a proposal.

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Class Projects

What are you going to create and why?

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The Client

In this class, you have two clients:

• Your fellow students in the class

• The professor for the course

Can you satisfy them both?

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Project Scope

What are the boundaries of the team projects?

• Must be completed in fifteen weeks

• Need a prototype that demonstrates main features

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Potential Benefits

Why are you doing this project?

Examples

• Create a marketable product

• Improve the efficiency of an organization

• Control a system that is too complex to control manually

• New or improved service

• Safety or security

• Get a good grade in this class

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Resources

Examples:

Staff: 3 to 5 students, with some help. How many hours per week? What skills do people have?

Time: Must be completed by end of semester, including operational prototype, documentation, presentation

Equipment and software: What special needs are there?

Client: Will the client be sufficiently available and helpful?

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Obstacles

Class Projects

Start-up time. Creating a team, scheduling meetings, acquiring software, learning new systems, ...

Business considerations. Licenses, trade-secrets, ...

Too ambitious. Nothing to show at the end of the semester.

Changing circumstances. Team members drop the class, ...

What else?

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How to Minimize Risk?

Class Projects

• Several target levels of functionality: required, desirable, optional

• Visible software process: intermediate deliverables

• Good communication within team and with the professor

Good processes lead to good software

Good processes reduce risk

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Project Topic Statement

A description of your group’s project selection

• Each group needs to pick a name. Hand in one sheet that lists the group name and its members.

• Each group needs to submit a project topic. This is an informal write-up that describes what the team is going to build.

• Short enough that everybody reads it

• Long enough that no important details are skipped