Bits 'n Bytes

Other Uses for PlantUML

November 28, 2021November 30, 2021Matt HayesLeave a comment

I like PlantUML and the whole diagrams-as-code ethos, where diagrams auto-generate from source code in the same repo.

Sure, the way PlantUML lays out objects and lines in free-form diagrams is arcane – try drawing anything beyond a few components, and you’ll end up in a pitched battle with the layout engine, resulting in a mediocre diagram in a state where you’re afraid to make changes, lest the lines and placement go all wonky (again).

Thankfully, things are better when using PlantUML to produce opinionated diagram types, where the layout rules are predetermined, such as sequence diagrams, mind maps etc.

I got to thinking – could I use PlantUML in the workplace, outside traditional architecture/code documentation, to help visualise other things? Only one thing for it – give it a go…

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Diagrams with C4 Model

May 10, 2020May 12, 2020Matt HayesLeave a comment

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This post is for everyone who draws computer pictures for a living…

The genesis for this post came from a comment on the diagrams-as-code post (via LinkedIn) that called out the C4 Model[1]:

I hadn’t heard of C4 Model before so I decided to check it out. A first look at the C4 Model web site piqued my interest – Continue reading →

IT Architecture – A Discussion on Coupling

April 18, 2020April 21, 2020Matt HayesLeave a comment

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In the world of IT architecture, coupling is a much talked about concept. But what is coupling, why is it important and what techniques/patterns can we use to optimise it?

That’s a lot to unpack, so let’s start with an example outside IT. Consider this trendy all-in-one desk lamp:

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It looks lovely, but what happens if the bulb fails, or you want to change the light colour? It is tightly coupled because the bulb component cannot be replaced separately, so the whole lamp must be replaced in these circumstances. Continue reading →

Beware the Perils of Audit-Driven Design

November 10, 2019November 10, 2019Matt HayesLeave a comment

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When you work in IT, security audits are par for the course. Like dental check-ups, they’re generally a good idea, but can still be painful (and expensive). They help uncover issues that need fixing, and raise senior exec visibility.

There is however a dark underbelly to security audits – they can drive counterproductive behaviours leading to unintended and undesirable outcomes.

Wouldn’t it be ironic if remediating a security audit item made your organisation less secure…? Continue reading →

Diagrams as Code (PlantUML)

August 17, 2019May 10, 2020Matt Hayes2 Comments

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Is a picture really worth a thousand words? What if that picture was a diagram?

A colleague recently introduced me to Diagrams as Code, using PlantUML, and in this post we explore the concept of diagrams-as-code, and how to use PlantUML.

Diagram Methods

Let’s start with some background. Diagrams should engage their audience, informing them and encouraging collaboration. Understanding the knowledge and needs of your audience is critical to creating a successful diagram.

We adjust the diagram to suit the audience, using different views of people / process / technology to inform and engage them. Often, we will draw multiple views of the same system to suit the needs of different audiences, as per Figure 1.

Multiple Views of the Same System

Figure 1 – Example of Multiple Views of the Same System to Suit Different Audiences

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What is a Network Traffic Flow? (Part 3)

July 30, 2019August 3, 2019Matt Hayes1 Comment

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Network traffic flows (flows) are useful for building a coarse-grained understanding of traffic on a computer network.

Following on from What is a Network Traffic Flow? and What is a Network Traffic Flow? (Part 2), this third post investigates flow metadata, how it adds value to flow analysis, and how to record and transport it. This is the good stuff, where flows become useful…

Figure 1 – What this blog post covers

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IP Fragmentation Lab with Vagrant

October 31, 2018November 1, 2018Matt HayesLeave a comment

Recently, I had a need to understand IP fragmentation better, so I built a lab to experiment with. I wanted it to be easy to setup, and built in a way that is repeatable by others, so I designed automation to stand it up with virtual machines in a hypervisor. The lab network topology is shown in Figure 1.

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Figure 1 – Network Diagram for IP Fragmentation Lab

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What is a Network Traffic Flow? (Part 2)

October 21, 2018July 30, 2019Matt Hayes2 Comments

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Network traffic flows (flows) are useful for building a coarse-grained understanding of traffic on a computer network. Flows provide a convenient unit for the measurement and/or treatment of traffic.

Following on from What is a Network Traffic Flow?, this second post delves into Internet layer flow considerations. Previously, we found that the definition of a flow is mainly arbitrary, primarily driven by the capabilities of hardware/software, and the use cases. We now delve further into the considerations around specific features and behaviours of IP.

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Figure 1 – Where this Blog Post fits in the Internet Protocol suite Continue reading →

What is a Network Traffic Flow?

September 26, 2018November 1, 2018Matt Hayes5 Comments

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Network traffic flows (flows) are useful for building a coarse-grained understanding of traffic on a computer network, providing a convenient unit for the measurement and/or treatment of traffic.

Flows can be measured to understand what hosts are talking on the network, with details of addresses, volumes and types of traffic. This view of the network can be useful for troubleshooting, detecting security incidents, planning and billing

But what exactly is a flow, and how is it defined?

This question sounds trivial to answer, however when we dig deeper we find nuances and corner cases that make flows interesting, and ultimately difficult to define. Continue reading →

Diagram Methods

We’re all doomed…