uccser/cs-field-guide

WEBVTT

Computer Science Education Research,
University of Canterbury, New Zealand
Subtitle file for the video "Computer Science Field Guide: Software Engineering"
Author: Alasdair Smith
Date: 15/02/2017
Modified by: Courtney Bracefield on 15/10/2019


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Software Engineering

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Software is essential to our lives.

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Imagine living without the internet,
Google, Facebook or your smartphone

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We expect our software to work correctly.

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A bug in a program can make it
really frustrating to use,

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or it could even crash your computer.

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But it could also be a lot worse than that.

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What if the software controlling
a nuclear power plant fails?

The next section has been broken up to make different
combinations of subtitles appear at the same time

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Or the software controlling an aeroplane?
[Screams]

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Fortunately, Software Engineering techniques
[Screams]

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can help us make software that works correctly.
[Yay]

end of section

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Making good software is difficult
because often software is huge and complex.

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Some large systems have
tens of millions of lines of code.

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If you printed them out on paper
and stacked them like a book,

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You'd get a stack that is
around a hundred meters high.

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That's as high as a 25 storey building.

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If you wanted to read through a program that size,
to try to understand how it works,

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It's likely to take you about 50 years!

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If some software takes almost a lifetime
just to read through,

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imagine how long it would take to write it.

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Of course no single person can do this alone.
We need teams of developers working on software.

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Sometimes three developers,

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sometimes ten developers,

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sometimes a hundred,
and sometimes more.

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This is where Software Engineering comes in.

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How do we get a team of developers
to write huge software,

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where all the pieces fit together,
it works reliably, and it does what the user wants.

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Software Engineering is about
so much more than just programming.

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In fact, the actual programming part
is usually only about 20% of software projects.

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Even today we are not good
at getting software development right.

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A survey in 2009 found that only
around a third of software projects succeeded.

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While a quarter of projects failed outright,

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or were cancelled before
the software could be delivered.

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Fortunately we now know a lot
about what works and what doesn't.

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In this chapter, we'll look at
some approaches that are doomed to failure,

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but are still used surprisingly often.

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And some approaches that seems to work a lot better,
and can helps us create software

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that does what it's meant to.

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Software Engineering