Feature Request: Standalone Edge Routing

[philip-alldredge]

Standalone edge routing was discussed on the forum at https://www.eclipse.org/forums/index.php/t/1086846/ as a possibility sometime in the future. It would be a great use for users who would like to manually position nodes and ports but have ELK layout the edges.
Is this something that is still being considered?

[le-cds]

It's still a feature we would very much like to have, but don't have any plans as to when someone might get around to implementing one.

[Nic30]

@le-cds the thesis label means that you have a student for this task or that you created the topic for student thesis?

[le-cds]

@Nic30 The latter. We're still looking for someone to work on this.

[khoshrou]

any news on this side?

[uruuru]

Unfortunately, no.

[Nic30]

It seems to me that it is only required to replace some parts of logic which generates a positions of nodes in columns. I did some proof of concepts but then I realized that I do not have time to write rest of app which would allow to drag components etc so I ended up using only upstream version of ELK.

[uruuru]

As you mention, the routing included in elk.layered makes heavy use of the fact that the nodes are partitioned into layers (including that edges spanning multiple layers are split by dummy nodes).

For a general standalone edge routing it is not always possible to properly create such a distribution for several reasons. An obvious one being that nodes may be "interweaved" in a way that prevents a partitioning.

Whenever it is allowed to slightly alter the positions of nodes (and the positions already roughly resemble what elk would come up with) but keep the overall topology, there are already processors included that would derive a corresponding partitioning.

[khoshrou]

is there any orthogonal layouting algorithm or library for javascript that we can use? seperating the responsibility, using elkjs for auto layouting and other library for dynamic layouting when user changes the place of nodes?

[uruuru]

There's an orthogonal edge router in libavoid/adaptagrams (cpp library).

Several years ago the KIELER project included a bride that made the cpp library available in Java. I couldn't see it on their current update-site though. Maybe @le-cds can elaborate on at what point in time support was dropped and point you to the sources in case you are interested.

[khoshrou]

Oo God, CPP library, I was hoping there is an npm package.
Years ago I did a little bit of search for layouting and as I know its a complex subject. Some times I am thinking maybe an AStart algorithm could do the job (It will be slow for large diagrams).
What do you think about this?

[Nic30]

https://github.com/Nic30/hwtIde/blob/master/hwtIde/static/hls/connections/a_star.js
Long story short:
I tried it and it worked somehow, but it was definitely bad idea (as there is endless number of corner cases..) so I deprecated the idea and moved to ELK.