[ctkrohn]

Building software like we build bridges.

There are a lot of things wrong with this analogy, but I think it still encapsulates a nice ideal. We'd like to get it right the first time, and make it last with minimal maintenance.

(This is for software engineering, not computer science)

[aaronblohowiak]

Physical construction envy is naive.

Many bridge-building projects go over time and over budget.

Most bridges have a feature list fixed years before construction is begun.

Bridges are static. Even draw-bridges do not adapt to their environment automatically, but require human intervention.

There is a categorical error when you try to apply construction practices of static things to the construction practices of dynamic things, hence the failure of waterfall. Note that the original papers that introduced waterfall actually suggest a system that more closely resembles iterative development than BUFD.

[regularfry]

If we found a way to make BDUF work reliably, it would transform the industry overnight, and turn software development into a recognisable engineering discipline. The fact that we haven't yet, and that one particular approach failed, doesn't mean that it isn't possible. Nor does it mean we should stop trying.

Iterative development is an interesting stop-gap, but it's certainly not the be-all and end-all we should be looking for.

[evanrmurphy]

> There are a lot of things wrong with this analogy

I think so. As a rule, when something can be developed incrementally rather than planned and engineered, it should be. This makes mistakes less expensive, allowing you arrive at a satisfactory end result in a fraction of the time.

This is one of the huge advantages of the web over desktop software. Initial delivery to the desktop and subsequent updates cost significant time and headache. Redeploying to the server is just a matter of running a script.

[aaronblohowiak]

"This is one of the huge advantages of the web over desktop software. Initial delivery to the desktop and subsequent updates cost significant time and headache. Redeploying to a server is just a matter of running a script."

This raises a good point about reuse. You wouldn't try to re-use the same bridge across a different span without modifications, but we require our software to run in different contexts (be it different web browsers, operating systems, versions of the language, et cetera.)

[regularfry]

Within reason, you definitely can: http://www.army.mod.uk/royalengineers/equipment/704.aspx

[bmj]

I think the bridge analogy can work a different, equally effective way: we can build software based on well-established and tested engineering principles, with tools and materials that have a known, verifiable set of behaviors.

I'm not a materials/mechanical engineer, but it seems that engineers can build bridges properly the first time (most of the time, right?) because they are working against a set of well understood, well tested physical laws (for lack of a better word). Even I write the perfect, say, shopping cart application, that bit of software still relies on programming frameworks, web servers, operating systems, and hardware systems that have known issues.

[27182818284]

If bridges were like software, as soon as a drunk driver ran through a bridge's guard rail the designes would have to follow up with a post that started, "We had some downtime from an accident, here is what we're going to do about it..."