Diagramming Spring MVC webapps

Some diagrams for the Spring PetClinic application

Following on from my previous post (Software architecture as code) where I demonstrated how to create a software architecture model as code, I decided to throw together a quick implementation of a Spring component finder that could be used to (mostly) automatically create a model of a Spring MVC web application. Spring has a bunch of annotations (e.g. @Controller, @Component, @Service and @Repository) and these are often/can be used to signify the major building blocks of a web application. To illustrate this, I took the Spring PetClinic application and produced some diagrams for it. First is a context diagram.

A context diagram for the Spring PetClinic application

Next up are the containers, which in this case are just a web server (e.g. Apache Tomcat) and a database (HSQLDB by default).

A container diagram for the Spring PetClinic application

And finally we have a diagram showing the components that make up the web application. These, and their dependencies, were found by scanning the compiled version of the application (I cloned the project from GitHub and ran the Maven build).

A component diagram for the Spring PetClinic web application

Here is the code that I used to generate the model behind the diagrams.

The resulting JSON representing the model was then copy-pasted across into my simple (and very much in progress) diagramming tool. Admittedly the diagrams are lacking on some details (i.e. component responsibilities and arrow annotations, although those can be fixed), but this approach proves you can expend very little effort to get something that is relatively useful. As I've said before, it's all about getting the abstractions right.

About the author

Simon is an independent consultant specializing in software architecture, and the author of Software Architecture for Developers (a developer-friendly guide to software architecture, technical leadership and the balance with agility). He’s also the creator of the C4 software architecture model and the founder of Structurizr, which is a collection of open source and commercial tooling to help software teams visualise, document and explore their software architecture.

You can find Simon on Twitter at @simonbrown ... see simonbrown.je for information about his speaking schedule, videos from past conferences and software architecture training.




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