Composition engine
The composition engine works out where the elements of a diagram go, supplies each notation's drawing conventions, and checks the finished diagram. The AI runs it as part of a loop: choose a layout grammar, compute the geometry, place the elements and connectors through the server, render the diagram and check it, then correct, for at most three passes.
Used by: ea-diagram-composition.
Runs where: local code execution. It needs Python 3, and pyyaml to read the notation bindings. Without code execution composed diagrams and the diagram check are not available (see How code engines work).
Logic: Deterministic for the geometry, and for loading bindings. Rule-based for resolving which binding applies to a diagram, and for the checks.
The engine has four parts, each described in its own subsection:
| Part | What it does |
|---|---|
| Layout grammars | The eleven rules for turning content of a known shape into geometry, which of them the engine composes, and how to tell which suits your content |
| Composition modules | The five modules that compute the coordinates, and what goes in and comes out |
| Notation bindings | Each modeling technology's diagram conventions held as data, and the loader that resolves which applies |
| Verification modules | The diagram check, the comparison of a reproduction with a reference picture, and the tool used to author bindings |