Of course, sequence diagrams make it clear with two separate arrows when control and data flow in different directions, but a lot of diagrams are of the "plain old boxes and arrows" variety.
Most of the article's diagrams are actually terrible in this regard.
It works because (node, edge, node) triplets then form propositions, the fundamental units of knowledge
Come to think of it, expertise researchers still do this today to make rough sketches of domains of study. The result is called a concept map.
This way sometimes the color can describe control, data, and sometimes even teams expected to implement this arrow by color coding teams.
The latter is very helpful for cross team meetings to make each group focus on the part of the diagram that will affect them the most, and give pointed feedback to assumptions and lack in specs
The database can live without the web server, but the web server doesn't work without the database.
Therefore webserver ---> database.
Key thing in that these deployment / context / container diagrams don't have a temporal axis. If you want to represent a flow, then you want a diagram where time has directionality, like a sequence diagram.
A > B > C
I still struggle with finding the best approach each time; I'd love more discussion of this stuff.
So https://www.jerf.org/iri/post/2025/on_layers_and_boxes_and_l... is an interesting take: put links in your diagram, so it functions as a table of contents. This seems most useful for someone who needs to start working on a project.
Similarly https://haskellforall.com/2026/02/browse-code-by-meaning asks how to show what's in a repo, but maybe file tree is not best and a diagram with links as table of contents is the answer.
That said practically speaking, I'm not sure what tooling easily creates working links in a diagram that looks good in any context, for instance mermaid might render on github but not a text editor.
Of course for other purposes maybe just go crazy with the diagram. I once had a coworker draw this super detailed master diagram, maybe 50-100 things on it, which I was told impressed senior government officials (after my manager recolored all the red to avoid connoting errors). But for the purpose of orienting developers a table of contents with links sounds better.
My reaction to the title was that trying to create the diagram is the mistake. If you can't explain it in prose, simplify.
A diagram is a dense way to express information. The same information in prose would take much longer for a typical human to absorb.
> If you can't explain it in prose, simplify.
Simplify what? The system? Usually you can’t just throw things away from the system to make it easier to describe.
I'd say it's a lossy way to express information. I find that architecture diagrams often cannot express the exact concepts I mean to communicate, so you're left trying to shoehorn concepts into boxes that are somewhat similar, and try to make up for the difference using a couple of cryptic words.
Prose doesn't look as nice, but allows me to describe exactly what I want to say, on any level of detail required. Of course, like with a diagram, you do need to put in significant time and effort to make it comprehensible.
A simplified explanation of the system is by definition lossy. This equally applies to a plain English description.
I’ve been in many design reviews and similar forums where someone has attempted to present a design through written English and finally someone says “we need a diagram here; this is too much to follow” and everyone in the audience nods because they are all lost.
One of the problems with trying to communicate system design with prose is that it makes sense to the person who writes it and has full context, but the audience is often left confused. Diagrams are often easier to follow specifically because they look under specified when they are.
You can't throw away requirements, but sometimes there don't need to be as many moving parts behind the curtain as you think in order to implement those requirements.
If you have a complex system, whether due to legacy or due to actual necessity, you aren’t going to redesign the system just for the sake of simpler explanation. Indeed if someone couldn’t explain the system in its current state I would have zero confidence they could successfully simplify it.
I was not considering the case of documenting already existing systems, just talking about the planning stage. Your point is well taken.
Is the diagram for marketing? A sales proposal? A business person using the product? Technical peer?
If you don't know this, you don't know if you have the right level of detail.
In my 20 years in this field I can easily count on one hand the times a diagram like this has been useful. I’ve seen more cases where they were clearly created to satisfy some exec that wanted to see it and never updated again.
> This can be as simple as adding a type suffix to a resource name (e.g. Orders Table, Results Bucket)
Don't encode types in names. And I disagree somewhat that the names are really needed at all.
> Making a “master” diagram
I think such a diagram is useful but obviously each top-level "box" in it doesn't need to contain all sub-components.
Why? Hungarian notation probably is probably going too far, but in cases where a single word is heavily overloaded encoding types is helpful (eg. image file, image table, image bucket).
And for your naming, I would probably have something like "Unnormalized orders", "normalised orders", "queued orders", but obviously I can't tell without much more information.
You want a diagram containing only icons? You will still need a legend somewhere that explains what each icon means, otherwise you will end up with at least as many interpretations of the diagram as there are readers of it.
And I'd say that that first image as shown is virtually useless anyway. There is little value in just laying out resource components without linking them to system operation in some way -- which means that that diagram can only be understood in its larger context, and that's typically not how diagrams are used: they end up being the main focus of discussions.
What a TERRIBLE way to store information in an AI era. Diagrams are so...human.
As someone who usually hates animations, in the example given I actually find them useful, assuming that they are representative of the actual flow. They are also unobtrusive because they are steady-state.
If your diagram is ugly, you're probably mixing levels of abstraction without acknowledging it. It's a forcing function on articulating what you know and what is outstanding. Something that is black boxed should be referenced as a black box.
I use a lot of data viz because it's a high bandwidth way to show relationships, dynamics, order of complexity and its location, information problems, scope, and de-noise data. So much can be explained by having AI make you a uml sequence diagram of a concept. it is unreasonbly effective. If you are making a "chart for management" and using powerpoint or native excel charts, you're probably creating garbage though.