Support VTK + Trame

[akaszynski]

Trame integration with Panel has been an ask for a while (see #4761), especially as the vtk.js serializer used within Panel is not as up-to-date as the one in Trame. It's possible to do this within an iframe via:

https://github.com/pyvista/panel-example/blob/15e1f5758ed79e08a8beeaf7042192e02c3e3f50/app/common.py#L26-L28

However, the trame backend requires a separate port to be open, meaning it's not possible to deploy this as a containerized application when the infrastructure only supports exposing a single port (e.g. port 8080).

Solution

We've recently implemented an example that uses jupyter-server-proxy to proxy the traffic from the Panel app to the trame port:

Repo - https://github.com/pyvista/panel-example
Demo - https://panel-example-production.up.railway.app/

This isn't an elegant solution since it requires us to patch the tornado handlers:
https://github.com/pyvista/panel-example/blob/15e1f5758ed79e08a8beeaf7042192e02c3e3f50/app/app.py#L38-L40

If you could point us in the right direction, we'd be happy to submit a PR to holoviz/panel.

CC @banesullivan and @jourdain

[jourdain]

An approach like we do in trame-jupyter-extension where we use the communication layer of the hosting environment (jupyter in that case) might be the proper integration mechanism. So ideally, if we can provide some JS and Python adapter to it, we should be able to complete such integration.

[MarcSkovMadsen]

See also #4761 (comment) and #2752.