Mary Shaw, “Prospects for an engineering discipline of software”. IEEE Software 7(6), pp. 15-24, Nov.-Dec. 1990

Mary Shaw, “Continuing prospects for an engineering discipline of software”. IEEE Software 26(6), pp. 64-67, Nov.-Dec. 2009

CS professor at CMU since 1972

Chief scientist of SEI 1984-7

Co-director Sloan Software Industry Ctr. 2001-6

Fellow of the ACM, IEEE, AAAS

Software Engineering

A label applied to a set of current practices for software development

Not really an engineering discipline But has a potential to become one Insights by comparing with other engineering

disciplines

So What Is Engineering?

Creating cost-effective solutions To practical problems By applying scientific knowledge To build things In the service of mankind

So What Is Engineering?

“Engineering relies on codifying scientific knowledge about a technological problem domain in a form that is directly useful to the practitioner, thereby providing answers for questions that commonly occur in practice. Engineers of ordinary talent can then apply this knowledge to solve problems far faster than they otherwise could. In this way, engineering shares prior solutions rather than relying always on virtuoso problem solving.”

Development of Engineering

Technological progress

craft

commercialization

engineeringproduction

science

Development of Engineering

Technological progress

craft

commercialization

engineeringproduction

science

Amateurs and virtuosos Knowledge does not propagate Waste of materials Small scale production Little commercialization

Development of Engineering

Technological progress

craft

commercialization

engineeringproduction

science

Skilled craftsmen Training in operational procedures Concern for cost and materials Large scale production Manufacture for sale

Development of Engineering

Technological progress

craft

commercialization

engineeringproduction

science

Educated professionals Use scientific analysis and theory Enabling of new applications Specialized market segments

The Situation with Software

Technological progress

craft

commercialization

engineeringproduction

science

rare cases

data structuresalgorithms

early large systems (SABRE)most startups

most software production

structured programmingTools (IDE)

state machines

lifecycles

The Situation with Software

Technological progress

craft

commercialization

engineeringproduction

science

rare cases

data structuresalgorithms

early large systems (SABRE)most startups

most software production

structured programmingTools (IDE)

state machines

lifecycles

typically called“software engineering”

Terminology

• What we call “software engineering” is actually tools, technology, and management practices

• Calling this “engineering” diverts attention from what needs to be done

• Need to focus on creating the theory and science for a real engineering discipline

Path to True Engineering

Define body of knowledge needed by experts 50,000 chunks of information 10 years of learning Attempt to start this: the IEEE Software Engineering

Body of Knowledge (SWEBOK)

Path to True Engineering

Define body of knowledge needed by experts Make this knowledge accessible

Finding it should be easier than deriving it anew: this has happened with Internet search

Documentation of libraries etc. Wikis, howtos, forums, and crowdsourcing –

extensiveness and currency at the price of authority, accuracy, and organization

Path to True Engineering

Define body of knowledge needed by experts Make this knowledge accessible Repetition and reuse

Design patterns Libraries, templates Integrated environments “Cut and paste” examples from the web?

Path to True Engineering

Define body of knowledge needed by experts Make this knowledge accessible Repetition and reuse Professional specialization

Nobody can master everything Specialization in technologies like real-time,

numerical computing Specialization in application areas like vision or

transportation Specialization in problem classes like HCI and

adaptive systems

Path to True Engineering

Define body of knowledge needed by experts Make this knowledge accessible Repetition and reuse Professional specialization Improve coupling between science and

commercial practice

Measuring Progress

• The “software development problem” will never be “solved”

• We will always build systems at the edge of our capabilities

• Progress is measured by the expansion of this edge,

• And by the growth in the number of classes of problems that are solved routinely

Philippe Kruchten, “Putting the 'engineering' into 'software engineering'”. Australian Softw. Eng. Conf., pp. 2-8, 2004

Developer of several large systems, e.g.

Canadian air traffic control system

Professor of SE, Univ. British Columbia

Developer of the Rational Unified Process

Software Engineering definition

According to IEEE Standard 610.12: “the application of a systematic, disciplined, quantifiable approach to the development, operation and maintenance of software”

Science: unconstrained study of laws, trends, and models, with emphasis on rigor and formalism

Engineering: perform trade-offs and compromises to make products with given level of quality under constraints of time, money, personnel, and legacy

Differentiating Characteristics

Software is different from other engineering disciplines:

No fundamental theory Computer science doesn't really help understand

software Compiled code is unstructured and brittle: a bug in

one place causes effects elswhere Software engineering limited to using best practices

Differentiating Characteristics

Software is different from other engineering disciplines:

No fundamental theory Ease of change

Much more so than bridges etc. But hard to do rigorously and take all ramifications

into account

Differentiating Characteristics

Software is different from other engineering disciplines:

No fundamental theory Ease of change Rapidly evolving technology

Can't consolidate body of knowledge Can't benefit from many years of experience Need to continuously retrain engineers

Differentiating Characteristics

Software is different from other engineering disciplines:

No fundamental theory Ease of change Rapidly evolving technology Negligible manufacturing cost

Easy to re-deliver a fix, so no pressure to get it right the first time

Differentiating Characteristics

Software is different from other engineering disciplines:

No fundamental theory Ease of change Rapidly evolving technology Negligible manufacturing cost No borders

Easy to outsource: don't need to ship goods

Consequences I

Waterfall model doesn't work It does in other fields where things don't change

Need to use iteration and incrementation Accommodate change Validate by execution and use, because theory

doesn't exist

Consequences II

Composability doesn't work Even if components are good, we don't know

whether their composition will be Again due to lack of theory And to the fact that technology changes rapidly

Possibly alleviated by architecture and model-driven design

A True Profession

Define and teach the body of knowledge What works in practice

Professional certification programs Liability and responsibility for products Shift from an inner focus (playing with

technology) to an outer focus (satisfying user needs)

Peter J. Denning and Richard D. Riehle, “Is software engineering engineering?”. Comm. ACM 52(3), pp. 24-26, Mar 2009

Worked on Multics at MIT

Inventor of the working set model for paging of virtual memory

Writer on the computing profession

Professor at several universities

President of the ACM 1980-1982

Aspects of Computing

Widely accepted: Mathematical aspects of computer science Scientific aspects of computer science Computer hardware engineering

Controversial: Software engineering

Do software development practices deliver reliable, dependable, and affordable software?

Learn from Other Engineers

Predictable system behavior Software often exhibits surprising behavior (bugs)

Design tolerances What the system can tolerate usually unspecified

Failure probability Hard to manage software risks

Separate design from implementation In software there is little specialization

Four Roles

Software architect Gather requirements and create specifications with

full system view Software engineer

Create economic and effective system design, address conflicts and constraints

Programmer Convert engineering design into working tested code

Project manager Handle coordination, schedule, and resources

Capers Jones

Software engineering Best Practices

McGraw-Hill, 2010

Software consultant

Promoter of function points

Collector of software data

Author of data-packed books

The 2008 Financial Crisis

For many years software was a booming industry Fast growth was achievable This masked many problems Due to the crisis investments dried out The software industry was put under pressure to

be efficient This requires focus and identification of best

practices Management more than technical

Best Practices

Software project staffing: How to do downsizing and layoffs Keeping motivation and morale Selection and hiring decisions Career planning and development Cultivating and using specialists Training managers Using contractors and outsourcing Software engineering certification

Best Practices

Software project management: Early sizing and scope Selecting software methods and tools Executive management support Canceling or saving troubled projects Software project organization Metrics and measurement Tracking milestones

Best Practices

Software management: Software configuration management Libraries and reuse Software change control (before release) Software quality assurance Internal software standards Deployment and customization Updates and releases Termination of legacy applications

Best Practices

Software properties: Software security and protection against hacking Software performance Complying with international standards Software warranties

Best Practices

The customers: User involvement in project Training customers and users Customer support after deployment

Best Practices

The classics: Software architecture and design Risk / cost / value analysis Communication in software projects Software reusability and certification Testing and inspection

From Craft to Solid Engineering

• Software security improvement Resilient applications, secure languages

• Software quality improvement Defect prevention and removal

• Software measurement improvement Need true picture of economics of development and

maintenance

• Maintenance and renovation of legacy applications Including reconstructing requirements and design