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The "source code is the blueprint for software" analogy doesn't work because the source only tells you what the application does, not what it's supposed to do. There is no way to tell, from the source code alone, whether or not what's been built is fit for purpose. You have to have some other document. The "specification is the blueprint" analogy is saying that the specification is a high level document that sets out what the application is meant to do.

As an example, imagine you're paid $1m to assess my super awesome new database. I give you the source code and tell you "the source is the blueprint." After reading through the code you discover there's no DELETE function. Have I built a clever immutable data store, or am I just an idiot who forgot a critical function? You can't tell that from the source.

I agree with you both.

Technically the source is a blueprint. But this comes down to scale.

Among other things I've worked on banking and corporate management applications. You cannot reason about the codebase at that scale. In these instances it's not possible to have a good outcome without a blueprint.

Using the building metaphor, you can get away with building a bird feeder without a blueprint. You can't get away with building a skyscraper without one. Houses, maybe. Either way, high level blueprints help everyone.

Good points - I think you need some kind of spec or something to reason about. But I don't think it needs to be complete because it is easier to iterate on software than buildings.

Taking the building metaphor, you can't clone a building locally and make changes to it, then ask another builder to review them, suggest some changes then push them out to a test environment before finally putting them into the real world. So for me, the building metaphor only goes so far but there are definitely some useful points in the article.

> you can get away with building a bird feeder without a blueprint

Definitely. But anyway, unless you have built several bird feeders or similar constructions before, your first version will probably be ugly and you'll have to iterate on it (i.e. find the right angles etc.) to make it better. What is of course fun, but costs you time.

I cannot tell that from the database, sure, because a database is simply structural information, not functional. Without a list of things that the database is supposed to do, it might be great or it might suck. Don't know.

But all modern systems have both structure and behavior. For every database there is a MVC model somewhere, for instance. And looking at those controllers, you should absolutely be able to tell whether the database is well-constructed or not.

Now there's another consideration: does the database structure map into some problem domain such that the introduction of new controllers will be supported? That's usually what people mean when they talk about architecture: the mapping of a problem domain over to a solution domain such that changes in the requirements have minimal impact on the solution.

In System-of-Systems work I'd argue yes, such work has some value -- as long as it is continually driving some kind of delivery (and not just "smart guys drawing boxes"). But in regular green-field system development? Not so much. That's because the tendency is to begin focusing on the wrong thing, the model instead of the user. Timeboxes help with this, so much so that I wouldn't advise any stand-alone architectural work in such an environment without team integration and time-boxing.

The analogy still holds.

If I hand you a blueprint for a skyscraper and I realize there is no lock specified for the front doors. Does that mean it's a lockless skyscraper or I'm speaking to a jackass who forgot a critical function related to security? You can't tell from the blueprint.

If a specification is required to be 100% complete for all things that could possibly relate in any way, then even blueprints don't qualify.

"TL;DR: Source code is the blueprint for software."

...and the 2x4s are the blueprint of a house and the steel beams are the blueprint of the skyscraper....

I'll take the TL;DR at face value since it was written by the author. The statement completely obliterates the entire concept of a blueprint or plan. By that reasoning, it is true everything is its own blueprint, and the concept has no meaning (of course this is a standard tautology).

And, simply nodding to CYA documents (for when the customers/end users come back saying that your product doesn't do X), or to docs for when formal proofs are needed, doesn't cover the concept.

The point of planning (or blueprinting) is to think about what you are going to build before you get out the tools, abstracted away from the specific tools that you'll use, and to then record and communicate those thoughts to all the stakeholders. It doesn't have to be a complete formal, engraved-in-stone blueprint, but a modest amount of actual thinking and planning goes a loooong way.

I've often found that with a little thought, we'll use a different tool than originally expected. If you expect to just dive in and sort it out in your source code, then you've already a priori restricted your choice of tool, and probably also your library, algorithm, etc. (of course if you only have or know one tool then, well, 'everything looks like a nail and who needs a blueprint?').

Without planning, you'll get what grows out of the first thing that comes to mind, not the best thing you could build. The mere fact that it manages to run or stand is not a defense of the bad process.

Planning is where the real thinking takes place. Sure, if all you want to do is exercise your programming skills and avoid thinking, then don't plan. But don't pretend that no one else should think or plan, or complain when someone else presents a plan to which you are expected to build (and don't be surprised 10 years on when you don't advance as far as you expected).

But the article directly says source code can't be the spec because it contains low level details. E.g. you implement something with map/apply instead of loops because that's all your programming language has, or your filter out some characters from a data stream because they often make a third party parser raise Exceptions you don't understand. These are programming details that the source code contains but the spec shouldn't. Therefore I think your argument is debunked by the main article already.

In any case it's a good discussion to have in this thread, which is why I gave you the up.

An Architect's drawing of a building contains every single detail of that house. It's not a high-level sketch of what needs to be built, it's an exhaustive plan for every part of the finished product that has been extensively iterated with the customer to make sure it's correct. Changes to this plan once complete are expensive.

So yes, it's exactly like code.

But I just wish people would stop comparing software development to construction. They're not alike at all, not even vaguely.

Programming is not like bricklaying, because bricklaying is deterministic and uncreative: there is one correct method of laying the bricks, and any two competent bricklayers will lay the bricks in exactly the same way. But there is never one single correct method of writing a program, and no two programmers will implement a feature in the same way.

Any attempt to create a specification so exhausting that it allows no deviation by individual programmers should stop pretending it's a spec and just write the damn code. In fact, the author of the article should probably stop writing specs and just iterate prototypes to achieve the same end: there's no difference between "understanding our programming task" in formal English or understanding it in code, except that the code is more useful and a lot easier to test.

There are many points worth of discussion in your comment. I just pick one for now. The details of the architects work.

I am no architect, so all I think about it can be true or false. But what I remember from an architect friend is that an architect's work is not really that detailed. It's like the photoshop mockup of a website, not like its source code. It doesn't say exactly which materials should be chosen or how many screws should be used to connect two ends. An architects design says "There is a wall x cm thick and y cm long". The source code says "There z bricks and the last one we had to cut to n cm" (sometimes a comment will state why it had to be cut). For the source code it is to some degree by accident the amount of bricks creates something that can be called a wall.

Well, my work is pretty detailed!

But all the information about the correct numbers of bricks, the slump of the mortar, the number and type of screws - these are all just library functions. Why would you re-write all that perfectly serviceable code for each project?

Getting a library to work for your use case is exactly one of those things that needs quite a few workaround which the bricks are not part of the library. The library is the earth you build your bricks on top and you need to put in some work that your bricks can stand on it.

I'd have to argue that an architectural drawing is not very detailed. And even if it is, the builder takes plenty of latitude in constructing the building. For example, the way that builders pick nails isn't by accounting for humidity levels or type of wood they use (older pressure-treated wood can corrode certain metals faster, same as newer wood can corrode others.) Instead, most of them just grab what they have, so when nails start failing after a few decades that's not their problem. Not like the architect said to use all galvanized nails everywhere.

But I digress. Here is how bricklayers and programmers are similar: they commonly work in the vacuum of their own workspace, without awareness of the environment that impacts their projects. So once the projects are launched, they're impacted by things that weren't accounted for.

If the foundation is too weak, the brick wall will sag. If nearby trees grow too close to the wall, the wall will bow inward or outward. If someone builds on top of the brick wall and doesn't reinforce it over 8 feet, the inspector will condemn the work. The bricklayers are paid to just lay bricks, so they won't care about the nearby trees, they won't care about the foundation, they won't care about what you put on top of the wall.

Programmers will build the project to spec, and come launch time, not account for a particular load signature because that was never their concern. Seen that time and time again. Substitute foundation for baseline server power, trees for amount of interrupting processes and meddling managers altering the original program at random, and you have a pretty reasonable comparison to bricklaying.

I'm sorry but if you employ programmers to build the project to spec without any awareness of the environment it's going to be deployed to, then no wonder you see that problem time and time again.

The problem here is not that you have insufficiently detailed specs, but that you're treating your programmers like bricklayers.

I strongly suggest you try bringing your programmers into the room during the specification process, even get them to write some prototype code to explore the tricky areas (something bricklayers don't get to do either). You'll probably find you get better code as a result because the people writing the code are aware of the environment the code will be deployed to.

What I'm insinuating here is that the environment is always more complicated than meets the eye. Granted, project complexity is as disparate as they're randomly different from each other.

* Would you bring bricklayers to the design meeting? No. Just the foreman. * Would you bring all programmers to the design meeting? No. Just the lead developer.

Yes, ideally you'd have all the programmers in the room, but more of them you introduce, you increase the communication overhead. And some projects involve dozens to hundreds to thousands of programmers and are complicated enough to not be able to bring everyone to the discussion table.

So what you have to do is use bricklayer programmers- trust them to do a single task right (warehouse uploaded photos, talk to APIs) but recognize their limits. I'm not faulting neither bricklayers nor programmers, but defining their borders more concisely.

yeah, I've worked on some big projects in my time, 100's of programmers. And all of them would have been done better by splitting the project up into smaller chunks and doing them in series.

I've never met a business problem in my 30+ years doing commercial IT that couldn't be split up into smaller problems with smaller solutions, but there seems to be a bias towards large teams and complex solutions in commercial IT.

I don't know what causes this (I suspect management ego or consultancy fees, the cause of most commercial IT problems), but it's a real problem. The vast majority of these huge projects fail, go massively over-budget, precisely because they're being managed wrong.

Programming is fundamentally not like bricklaying, because it's creative not deterministic. Better, more detailed and more complete specs won't make more successful projects.

If you have too many programmers to bring them into the room when you're specifying the problem, then your project team is too big. The answer is not to exclude programmers and create more detailed specs, because programmers working to a spec like that won't write good code.

I know, I've been there. One project in particular stands out. We had detailed specs for a range (a few hundred) of middle-layer business routines. I received a function spec, wrote the function, wrote a few tests that the function did what it should do, ticked the box. Rinse and repeat for months. There were people working in a similar fashion on the front end and database layer. The system went over-budget, never worked, and was finally scrapped. It's not hard to see why, when the entire system was being written in this fashion. Programming is not like bricklaying.

If you think about it for 5 minutes you'll see that "bringing more programmers into the room increases communication overhead" implies that there is some information that is required to be passed from the customer to the programmer. The solution to this problem is obviously not to exclude the programmer and reduce the information passed to them, because that will lead to inferior code because the programmer is missing information. Instead reduce the amount of information the team is dealing with by segmenting the problem better.

I was going to go the other way here and point out that blueprints are actually code for buildings.. the builder is the compiler I guess?

But blueprints are done at various scales and they differ in complexity and format ie. sketches, models, schedules. They also often come with a book of specifications, and these are typically only referred to when ordering parts or if something goes wrong - and they are always open to interpretation..

Yes this is exactly how my organization works, because my team leader is too lazy to spec anything out.

Its an absolute nightmare when something doesn't work as expected, because rather than checking a specification that will take a couple of seconds to read, you basically have to debug software, which takes a lot longer.