Nasdanika SDK Runtime - Draw.io

Most diagrams are drawn once, looked at a few times and then left to drift away from what they describe. They don't have to be. A diagram drawn in Draw.io is a structured document, and with a little discipline it can be documentation, configuration, a program's wiring or the source of a model, while it stays a picture anyone can open and change.

The why: the visual communication continuum

The first part needs no code. It places every diagram on a continuum: a picture, an interactive diagram with tooltips, links and layers, a documented diagram, a diagram as data that a program checks and reports from, an executable diagram, and a diagram as a model. It gives rules for choosing a point: start on the left, move right when readers ask the same question twice or when a program needs the answer, and never redraw to move, because each point keeps the file of the point before it.

The how: Draw.io documents from Java

The second part is for Java developers who are handed diagrams and asked to do something with them. It covers the Draw.io module of the Nasdanika SDK Runtime, a small Java library with few dependencies:

* The document model - Pages, layers, nodes and connections, mirroring Draw.io's file format closely enough that what you learn holds for the format itself.

* Navigating and querying - Properties and placeholders, selectors and property paths, and links between pages, elements and documents.

* Creating and changing diagrams - Geometry and order included, saved back as files Draw.io opens.

* Rendering - Pages as PNG and SVG, and videos, drawn by Draw.io's own viewer in a browser driven by Playwright.

The last part shows where the runtime goes next: diagrams as models, generated and laid out diagrams, and diagrams for AI assistants.

Who it is for

- People who draw: architects, analysts and engineers who use Draw.io and want their diagrams to do more than sit in a wiki.

- Java developers who need to check, generate, publish or synchronize diagrams.

- Anyone building tools on diagrams.

How it keeps you honest

Every listing is included from the module's tests and runs when the book is built. Every figure is a PNG with the Draw.io diagram embedded: open it in Draw.io and edit it, or load it with the API and get the document the next listing works on. Status labels mark what is PLANNED and what is a SKETCH.

This is a Nasdanika Zephyr Book, an in-depth manual for one part of the Nasdanika SDK Runtime, and it stands on its own: you don't need to know the runtime to start and finish here. The code needs Java 25. The text is licensed under CC BY 4.0 and the code under EPL-2.0.