Why diagrams are crucial to your open supply mission documentation

In case you’ve ever visited a mission on GitHub (as an illustration) with the intention of understanding the way it matches into a bigger system, you will recognise the sigh of aid you expertise if you discover a diagram or two on (or simply reached from) the preliminary touchdown web page. That is an article concerning the significance of structure and particularly concerning the significance of diagrams.

I am a powerful open supply advocate, however supply code is not sufficient to make a profitable mission, and even, I might add, to be a actually open supply mission: Your documentation mustn’t simply be obtainable to everyone, however accessible to everybody. If you wish to get folks concerned, offering a manner in is significant.

Past that, I feel we now have a accountability (and alternative!) in direction of variety in open supply. Offering diagrams helps deal with (not less than!) 4 kinds of variety:

  • Folks whose first language just isn’t the identical as that of your most important documentation
  • Individuals who have issues studying numerous textual content (e.g., these with dyslexia)
  • Individuals who assume extra visually than textually (like me!)
  • Individuals who need to perceive your mission from completely different factors of view (e.g., safety, administration, authorized)

This text took place after I attended a digital demo just lately. The demo did not work, however none of us was pressured by that: it was an inside demo, and these items occur. It is a spot we’re all accustomed to, and all of us felt for the mission’s crew lead (who was presenting the slide deck) when, a number of slides in, a message popped up on her display screen from one in every of her crew members saying “Demo NO GO!”

After apologising, she requested if we needed to bail utterly or simply focus on the knowledge they’d available. We opted for the latter—in any case, most demos that are not foregrounding consumer expertise parts do not present a lot past terminal home windows, not less than greater than most of us might faux in half an hour or so anyway.

Fortunately, the members of the crew presenting the demo had numerous details about what it might have proven us and a very good architectural diagram to debate, so we had a productive session regardless of the issues with the demo. She answered a few questions, after which I piped up with one about safety.

This text might have been concerning the safety failures in a mission that was exhibiting an early demo: one other instance of safety being left till late (typically too late) within the course of, when it is tough and costly to combine. Nonetheless, it was clear that the crew had given thought to particular features of safety, each on the community (in transit) and in storage (at relaxation). Though there was most likely room for enchancment (and when is not there?), a crew member messaged me extra documentation through the name that allowed me to grasp a few of the selections the crew made.

What this text is about is the truth that we had been capable of have a dialogue in any respect. The slide deck included an structure diagram exhibiting all the most important parts with arrows exhibiting the route of knowledge flows. It was clear and colour-coded to point out the provenance of the completely different parts—which parts had been sourced from exterior tasks, which had been from inside tasks, and which had been new to this demo. The folks on the decision—all technical—had been capable of see at a look what was occurring, and the crew lead offering the outline had a transparent clarification for the assorted flows. Her crew members chipped in to reply particular questions or to supply extra element on explicit factors. That is how technical discussions ought to work, and there was one factor specifically that happy me (past the truth that the mission had considered safety in any respect!): there was an architectural diagram to debate.

There will not be sufficient safety consultants on this planet to go round, which implies that not each mission has the chance to get each stage of its design pored over by a member of the safety neighborhood. However when it is time to share, a diagram is invaluable. I hate to consider the variety of instances I have been requested to have a look at a mission to offer my ideas about its safety features and located that every one that is obtainable is a mixture of code and part documentation, with no clarification of the way it all matches collectively and, worse, no structure diagram.

Once you’re constructing a mission, you and your crew are sometimes so into the nuts and bolts that you simply know the way it all matches collectively and might maintain it in your head or describe the important thing factors to a colleague. The issue comes when somebody must ask questions of a special kind or assessment the structure and design from a special slant. An image—an architectural diagram—is an effective way to coach exterior events (or new members of the mission) about what is going on on at a technical stage. It additionally has quite a lot of additional advantages:

  • It forces you to consider whether or not every thing can be described on this manner.
  • It forces you to contemplate ranges of abstraction and what needs to be proven at what ranges.
  • It could possibly reveal assumptions about dependencies that weren’t beforehand clear.
  • It’s useful to point out information flows between the assorted parts.
  • It permits for easier conversations with folks whose first language just isn’t that of your most important documentation.

To be clear, this is not only a safety drawback—the identical goes for different non-functional necessities, corresponding to high-availability, information consistency, efficiency, or resilience—however I am a safety man, and that is how I expertise the difficulty. I am additionally conscious that I’ve a really visible thoughts, and that is how I wish to get my head round one thing new. However even for many who aren’t visually inclined, a diagram not less than gives the chance to orient your self and work out the place you should dive deeper into code or execution. I additionally imagine that it is subsequent to unattainable for anyone to contemplate all the safety implications (or any of the higher-order emergent traits and qualities) of a system of any important complexity with out architectural diagrams. And that features the individuals who designed the system as a result of no system exists by itself (or there is no level to it), so you’ll be able to’t maintain all of these items in your head for any size of time.

I’ve written earlier than concerning the e-book

Constructing Evolutionary Architectures

, which does a fantastic job of serving to tasks take into consideration managing necessities that may morph or change precedence. Unsurprisingly, the e-book makes a lot use of architectural diagrams.


, a mission with which I am

intently concerned

, has all the time had numerous diagrams, so I am conscious that there is an overhead concerned right here, each in updating diagrams as designs change and in contemplating which abstractions to supply for various customers of our documentation, however I really imagine that it is price it. Each time we introduce new folks to the mission or give a demo, we be certain that we embody not less than one diagram (and infrequently extra), and after we get questions on the finish of a presentation, they’re virtually all the time preceded with a phrase corresponding to, “might you please return to the diagram on slide



I urge you to create diagrams, each in your profit and likewise for anybody who’s going to be your mission sooner or later. It is a key a part of being an open mission—the opening of the structure implies that the code, and due to this fact the mission itself, turns into extra accessible and extra open to the broader neighborhood. Members of the neighborhood will respect it (and so do you have to). Your diagrams do not must be excellent. However they do must be there.


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