Tag Archives: ObjectAid

Create UML diagrams with simple DSL – PlantUML



Historically I disliked creating design UML diagrams, because the tooling for it mostly requires drawing boxes and connecting them with lines or arrows. I find such workflow very time consuming and wasteful. This short blog post will describe much better way to create UML diagrams.

But first of all, you may argue that UML importance in today’s agile software development world is fading out. I would agree partially.

Creating UML Class Diagrams

From my point of view UML class diagrams are needed very rarely. I can find only two use cases for it:

  • To analyze existing code base
  • To communicate suggested design with the team

When you need to analyze existing code base, class diagrams can be easily generated by your IDE from the existing code. IntelliJ idea provides this as part of payed version:UML

To find out how to create such diagram, read this IntelliJ IDEA documentation. It is also easy with Eclipse or it’s flavors (e.g. Spring Tool Suite):


You just need to use plugin called ObjectAid.

When we need to sketch class diagram upfront to consult design with the team, I would suggest to create prototype with desired class structure instead and generate class diagram from the live code (again with IDE). You may find some important facts about the design while creating prototype. There’s no need to create logic and tests, just APIs of the design.

And of course when you don’t need such generated diagram anymore, just wipe it out. Low level design may change easily and you don’t want to keep outdated diagrams around. You can generate new diagram from live code easily.

Non-Class diagrams

So when we need Class diagram, it’s smart to generate it from live code. But what about other UML diagrams like:

  • Structure diagrams (except Class diagram)
  • Behavioral diagrams
  • Interaction diagrams (especially useful is Sequence diagram from this bucket)

I personally created only few Use case and Flow chart diagrams during my career. But Sequence and Component diagrams are very useful to document high-level design decisions. Of course you don’t want to have them very detailed, but at high level designer intentions and considerations are sometimes good to document.

But the tool that is used for designing these diagrams has to be very easy to use and flexible. Sorry Visio or Enterprise Architect, I don’t include you into this bucket (although I have to admin I haven’t use EA for long time).

My tool of choice it PlantUML.  We can define design with very simple DSL. Therefore instead of connecting boxes and lines on canvas, we can focus on design itself. It can be used as standalone application but it also have impressive list of integrations. So you can easily use it with your IntelliJ IDEA, Eclipse or Spring Tool Suite.

Very compelling fact for me, is that DSL which defines diagrams can live with the project code-base and also be handled by source control system, with all the goodness it brings. This is simple screenshot from IntelliJ:



Generate UML class diagrams from code with ObjectAid



I’ve used ObjectAid Eclipse plugin for years. But very few of my colleagues were aware of it. This fact surprises me and therefore I would like to highlight it. It is very handy for generation of UML class diagrams from your code. It is also invaluable for analyzing of existing design.

One of the top UML tools is Enterprise Architect. But I was never happy with Enterprise Architect usability. I find it much easier to sketch class structure in Java and generate  UML class diagrams by ObjectAid. Advantage of this approach is that you have basic skeleton of the module. You can check-it in, so that team can start working on implementation.

Have to mention that it’s commercial product, but Class Diagram version is free.¬† For my UML class diagrams needs (design analyze, generating UML diagrams for documentation, modules design sketching) it was enough so far.

They provide also paid Sequence diagram and Diagram Add-On versions. To be honest I have never tried these. For sequence diagrams I was using only Enterprise Architect so far. I would be definitely pushing towards buying ObjectAid licenses if we wouldn’t have Enterprise Architect licenses already.

There’s no point for me to provide detailed description of it, because ObjectAid site contains short and explanatory overview. I suggest to start with One-Minute Introduction.

Everyone understand how inaccurate can UML class diagrams become. Keeping them up to date manually doesn’t make sense at all. ObjectAid fills this gap, because you can maintain your class diagrams up to date. But I had problems in the past when diagrams couldn’t handle renaming or moving of Java classes. Not sure if this is still problem of recent versions, because my diagrams are short lived. I can easily generate new diagram by just dragging appropriate classes into Class diagram editor. This is beauty of ObjectAid plugin.