Adding support for edge to edge connections

[Mc-Hoyos]

In UML, associations are represented by edges, and other edges can be connected to the association edge. Is it possible to support this in sprotty?

[spoenemann]

Yes – you're free to model your Sprotty graph how you like. The interface for edges simply uses model element ids for source and target:

sprotty/packages/sprotty-protocol/src/model.ts

Lines 78 to 83 in f9b2433

	export interface SEdge extends SModelElement, Partial<Selectable>, Partial<Hoverable>, Partial<Fadeable> {
	sourceId: string
	targetId: string
	routerKind?: string
	routingPoints?: Point[]
	}

However, you need to change the implementing class for such edges. The default SEdgeImpl inherits from SRoutableElementImpl, which assumes that the source and target are closed shapes:

https://github.com/eclipse-sprotty/sprotty/blob/master/packages/sprotty/src/features/routing/model.ts