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CS 501: Software Engineering

Lecture 24

People 2

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Course Administration

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CS 501: Software Engineering

Completion of Lecture 23

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An Old Exam Question

You have hired two new members of staff.

(i) The first has just graduated from the Cornell M.Eng. program in computer science, with no work experience.

(ii) The second has five years' experience in developing advanced applications, but has never worked on this type of computer.

Some of the development tasks are more interesting than others. Some tasks are harder than others. Some are more time critical than others. What approach would you use in allocating the tasks to these two new members?

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Bad Answers

"The Cornell graduate has more expertise to tackle the harder tasks." What makes you so superior?

"The Cornell graduate is used to time-critical tasks (course assignments)." Sorry, that's not real.

"The Cornell graduate should be given interesting work to make him/her keen to continue with the company." But who cares if you leave?

A raw graduate is still a trainee -- the most junior person -- much to learn -- no experience of production quality development.

But, hopefully, with great potential!

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Good Answers

• Both should have the potential to produce excellent software under tight time constraints.

• Both new employees need to learn the technical environment. Expect them both to work slowly until they learn the environment.

• The junior (raw graduate) needs mentoring. The senior (experienced developer) might work independently or lead a team.

• The junior should not be put on time-critical tasks. The experienced developer might be.

• Both people should be given a mixture of more and less interesting tasks. Discuss the allocation with them.

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CS 501: Software Engineering

The Human Computer Interaction Experiment

Sadat Shami

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http://knet.hci.cornell.edu

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From Lecture 1:Overall Aim of the Course

We assume that you are technically proficient. You know a good deal about computing, can program reasonably, can learn more on the job.

When you leave Cornell, you are going to work on production projects where success or failure costs millions of dollars.

Soon you will be in charge! It may be your money!

We want you to make your mistakes now and learn from your mistakes.

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Future Experience

What will you be doing one year from now?

Ten years from now?

1. Careers outside computing

2. Careers in which you personally continue to do technical work

3. Careers in which you are responsible for the technical work of others

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Careers outside Computing

A computing background can be valuable in any career: management, government, law, medicine, philanthropy, etc.

Education in computing is an asset:

• Computing is a vital part of almost every organization

• Education in logical thinking, tackling large tasks systematically

Education in computing is a potential weakness:

• Not every problem can be solved by rational thinking alone

• Importance of skills with people, judgment, etc.

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Technical Careers

Super-technical positions

A very few senior positions which are almost entirely technical:e.g., industrial research, universities

Even these have substantial organizational aspects

Mid-level technical positions

Numerous mid-level professional positions

Can be state-of-the-art or dead-end

Computer professional report satisfaction with their choice of careers

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The Connection to the Client:CS 501 Model

Client

Software development team

Course team

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The Connection to the Client:Typical Organization

Customers

Software development

Marketing

Quality assurance

Product management

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Product Manager

The task of the Product Manager is to ensure that the right product is built and that the right trade-offs are made between timeliness, functionality and costs.

This requires an understanding of:

• Marketing and business considerations

• Technical options and design criteria

• Communication among groups with different expertise and priorities

A good Product Manager has strong technical and management skills (e.g., a computer scientist with an MBA)

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Quality Assurance

The task of Quality Assurance is to ensure that software products are built correctly.

At Microsoft, the Quality Assurance staff is as large as the Software Development staff.

• Develop tools and methodology for creating software that is:

testablemaintainablefree of bugs

• Validate software by reviews, inspections, testing, etc.

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Careers that take responsibility for the Technical Work of Others

A common career progression is from being a technical expert to leading others who do technical work

Senior personnel must be familiar with both the strategic organizational aspects and the computing aspects of the work, e.g.,

EntrepreneurChief Information OfficerSenior consultant

• Requires good technical insight, but not detailed technical expertise

• Requires organizational, marketing, personnel, financial expertise

Product management is a good background for such positions

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Career Flexibility

Nobody knows where computing will go in the future, but …

If you do not learn continuously, you are going out of date fast!

• Go to seminars, conferences, training courses

• Be inquisitive – discover things for yourself

Technical expertise is most valuable when combined with other skills

• Understand the organization that you are part of, e.g., budgets, marketing.

• Develop organizational skills, e.g., presentations, writing, leadership

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Software Development as a Profession

Question: Is software development a branch of engineering?

Answer: It depends on how you define engineering.

Software development demands a high degree of

professionalism.

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What is Engineering?

A definition of engineering

The profession of:

... creating cost-effective solutions ...

... to practical problems ...

... by applying scientific knowledge ...

... and established practices ...

... building things ...

and taking responsibility for them!

With this definition, software development is clearly engineering

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From Lecture 1:Professional Responsibility

Organizations put trust in software developers:

• Competence: Software that does not work effectively can destroy an organization.

• Confidentiality: Software developers and systems administrators may have access to highly confidential information (e.g., trade secrets, personal data).

• Legal environment: Software exists in a complex legal environment (e.g., intellectual property, obscenity).

• Acceptable use and misuse: Computer abuse can paralyze an organization (e.g., the Internet worm).

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An Old Question: Safety Critical Software

A software system fails and several lives are lost. An inquiry discovers that the test plan did not consider the case that caused the failure. Who is responsible:

(a) The testers for not noticing the missing cases?

(b) The test planners for not writing the complete test plan?

(c) The managers for not having checked the test plan?

(d) The client for not having done a thorough acceptance test?

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Client Responsibility

• Organization culture that expects quality

• Appointment of suitably qualified people to vital tasks (e.g., technical team that will build a critical system)

• Reviewing requirements and design carefully

• Establishing and overseeing the acceptance process

• Providing time and incentives that encourage quality work

• Working closely with the software team

Accepting responsibility for the resulting product

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Computing Management Responsibility

• Organization culture that expects quality

• Appointment of suitably qualified people to vital tasks (e.g., testing safety-critical software)

• Establishing and overseeing the software development process

• Providing time and incentives that encourage quality work

• Working closely with the client

Accepting responsibility for work of team

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Software Developers and Testers: Responsibilities

• Carrying out assigned tasks thoroughly and in a professional manner

• Being committed to the entire project -- not just tasks that have been assigned

• Resisting pressures to cut corners on vital tasks

• Alerting colleagues and management to potential problems early

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What is Engineering?

A second definition of engineering

A professional who

… is licensed by a professional society

… based on a set educational program with a standard body of knowledge and specified experience

… who is the only person permitted to oversee certain tasks

If this is your definition of engineering it is hard to see it applied to software development

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From Lecture 1:The Craft of Software Development

Software products are very varied

--> Client requirements are very different

--> There is no standard process for software engineering

--> There is no best language, operating system, platform, database system, development environment, etc.

A skilled software developer knows about a wide variety of approaches, methods, tools. The craft of software engineering is to select appropriate methods for each project and apply them effectively.

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Crafts, Science, Engineering

Production

Craft

Commercial

Science

ProfessionalEngineering

From: Shaw and Garlan

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Crafts, Science, Engineering

Production

Craft

Commercial

Science

ProfessionalEngineering

From: Shaw and Garlan

algorithmsdata structures

compiler construction

software developmentmethodologies

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Engineers, Texas and the ACM

• Proposal in the Texas legislature to license professional engineers in Software Engineering

• What role should the ACM play?

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From the National Society of Professional Engineers

• Only a licensed engineer may prepare, sign and seal, and submit engineering plans ... for public and private clients.

• Licensure for individuals ... is a legal requirement for those who are in responsible charge of work, ...

• Federal, state, and municipal agencies require that certain [positions] ... be filled only by licensed professional engineers.

• Many states have been increasingly requiring that those individuals teaching engineering must be licensed.

• State engineering boards are increasingly ... obtaining the authority to impose civil penalties against unlicensed individuals.

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Software Engineering as Engineering?

• Part craft -- part engineering

• Embryonic scientific basis

• Evolving body of expertise

ACM conclusion: Software Engineering is in too much of a craft, too uncertain, and changing too much for the apparatus of a profession

• Who has the expertise to define a formal Body of Knowledge?

• What would be in an accreditation exam?

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Software Engineering Institute Capability Maturity Model

1. Initial -- no effective management processes

2. Repeatable -- requirements management, project planning, scheduling and tracking, quality assurance, configuration control

3. Defined -- conformity to defined processes, design and code reviews, communication procedures, personnel development

4. Managed -- software quality management, quantitative process management

5. Optimizing -- continuous improvement of processes

Question: What is the evidence that the Capability Maturity Model reflects effective Software Development?