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Architectural diagrams: what to know, and how to draw one

PostsSoftware development
Georgina Guthrie

Georgina Guthrie

February 15, 2022

Sometimes, it’s helpful to get a big-picture view of something for context — and architectural diagrams do just that. In a nutshell, they show how elements within a system interact with each other in a wider process.

There are many different types of architectural diagrams, all of which vary depending on what you’re trying to accomplish. They’re used in construction, engineering, security, IT, sales — basically any process that involves stages and stakeholders.

For this walkthrough, we’ll focus on software architectural diagrams. They break structures down into layers that show how specific systems interact with users and other systems.

Design diagram vs. architecture diagram

Many people confuse the two, but they’re completely different things. An architecture diagram describes what you’re building, how stakeholders interact with it, and where constraints lie. A design diagram explains how to build it.

To use an example: let’s say you’re building a football stadium. An architecture diagram will tell you what the architect wants, plus details about the investors, the building contractors, and local laws. It may include a summary of the building, plumbing, and electrics. However, its main goal is to show you how to meet all these groups’ needs. Some parts show the concept from everyone’s point of view; others address individual needs. A design diagram, on the other hand, simply goes into detail about how to build the stadium, stage by stage.

Two ways architectural diagrams can help you

1. They help with comprehension

A picture is worth a thousand words, or so the saying goes. Similarly, architectural diagrams help convey complex information in a single image.

  • Architectural diagrams show systems. Displaying information visually allows the viewer to see everything at a glance, including how elements interact. This is especially useful when making changes. You’ll be able to see the downstream effects of a given change more clearly.
  • Architectural diagrams also break down complex systems and processes into layers. So, rather than trying to comprehend everything at once, you can zoom in and focus on smaller sub-processes or systems.

2. They improve communication and collaboration

One of the main issues software engineers face is consistency. When you’re working on anything that involves multiple people, there’s always a risk of miscommunication and discrepancies between project teams and developers. It’s crucial to standardize information, which is where an architectural diagram becomes helpful.

Bear in mind that architectural diagrams can be inconsistent too — which is why they must be standardized, accurate, and detailed. Diagrams communicate the application’s elements, relationships, and properties over time to a range of different stakeholders, so they need to follow a clear system.

Types of software architecture diagrams

Not all architecture diagrams are the same, and you can use them to model different aspects of a system. Let’s look at the most common types of software architecture diagrams.

Application Architecture Diagram

An application architecture diagram shows the structural layout of a software system and how it interacts with other systems. This type of diagram provides a high-level overview of how the components make up the system. It’s common to group application diagrams into layers that detail how the system works at different levels.

Data Architecture Diagram

Think of all the personal information you submit through websites and software every day. Contact information. Identification numbers. Banking details. Organizations are increasingly responsible for handling large amounts of internal and external data.

A data architecture diagram provides a breakdown of how data flows through a system and where it’s stored at different points. This type of diagram is useful for finding ways to improve data processing. and when you’re ready to scale up a system, it’ll help you maintain efficiency.

Integration Architecture Diagram

An integration architecture diagram shows how the internal components work together and how they’ll work with external systems. This type of diagram is useful for designing software that will integrate with other programs.

How to draw an architectural diagram

Architectural diagrams should be self-explanatory. If they’re not, then they’re failing. To make sure yours is easy to understand, keep variable elements consistent, and explain everything in the legend, key, or glossary. Here are some rules to help you.

1. Document your shapes

The meanings of shapes vary from diagram to diagram, so to avoid confusion or misinterpretation, be sure to document the ones you’re using — even if it’s just a simple box. And be consistent throughout.

2. Label the edges

The same goes for edges. Whether you use a dotted, dashed, or straight edge, make sure you properly label it in the diagram legend when using multiple border types.

3. Keep your arrows consistent

Arrows denote data flows and dependencies, but that same line could represent different things within those two categories. For example, a line could depict a relationship, but that relationship could represent a dependency or an implementation. Minimize the risk of ambiguity by adding relevant information to all arrows.

4. Use colors sparingly

When it comes to colors, less is more. You should only really use them to emphasize certain parts of the diagram. If you add color — like shapes, borders, and arrows — every choice needs to follow the same logic and be consistent and properly labeled. Otherwise, people will ask why certain things are the way they are, which negates the point (and effectiveness) of the diagram.

5. Use multiple diagrams, if necessary

When you have multiple stakeholders, you may need to include a large amount of data. If this is the case, create several diagrams for the different viewpoints rather than creating an unintelligible spaghetti beast. And whether you have one diagram or ten, remember to keep everything (boxes, shapes, borders, and colors) uniform throughout.

6. Merge incomplete diagrams

If two diagrams both represent one process or system but they’re incomplete, consider merging them.

7. Include legends/keys/glossaries

A legend helps everyone understand your diagram. Remember, just because your team knows a certain acronym, it doesn’t mean a stakeholder will.

8. Use diagramming software

Using a dedicated cloud-based diagramming tool allows you to track changes in real-time and revert to previous versions if necessary (without the need for manually tracking versions on the server). This helps with traceability, minimizes the risk of someone working on the wrong document, and cuts down on admin.

Things to watch out for

  • Missing elements, broken relationships, or isolated entities: these inconsistencies could point to a wrong or incomplete diagram.
  • Unexplained acronyms: always write the expanded acronym first, and then use the abbreviation. It’s also a good idea to put all acronyms in a glossary for reference.
  • Vague or generic terms: avoid anything that could be interpreted in different ways.
  • Unexplained technologies, frameworks, or scripting languages: these shouldn’t feature in the diagram, but you should include a rationale as to why you’ve chosen certain things.
  • Assumptions: avoid alluding to further explanations or diagrams, such as, “I will explain this later.” Over time, your diagram will pass through various groups and stakeholders, and they may not have access to this additional information. Make it self-contained.
  • Too much information — or too little: a good architectural diagram isn’t cluttered. Yet, it should include all relevant information with the diagram itself. To strike this fine balance, revise and improve upon your first draft. Remember, it’s all in the edit.

Final thoughts

Many software projects lack proper documentation because people see it as time-consuming or confusing. But not having the right diagram for the job is like trying to drive somewhere without planning your route. The time you spend getting lost and backtracking dwarfs any upfront time you would have spent mapping the journey.

It’s the same with architecture diagrams. Setting out this information helps you and your stakeholders navigate the project, bringing clarity across the board. Use cloud-based diagramming software to create a diagram everyone can access, making it easy to maintain consistency and track changes in real-time. This means you won’t have to send out version updates or worry about people working on or viewing an outdated diagram. Everyone is on the same page.

Cacoo’s software allows you to insert and edit your infrastructure directly in the cloud-based diagramming tool. Try it today!


This post was originally published on October 9, 2019, and updated most recently on February 15, 2022.



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