Retrieve components properties outside of dash app

[emmanuelle]

I have the following usecase: I would like to have a jupyter notebook in jupyterlab where I do some computations (say, on images), then create a dash app to process my data, and then retrieve (back) the value of some component properties (for example an image generated by a segmentation made from users annotations), so that I can continue the computations in the notebook. Is this possible at the moment?

I'm happy to give more explanations or provide a notebook with some mock-up code if it's clearer.

[chriddyp]

The Dash apps are run in a separate process which has its own memory scope. So, extracting the scoped variables from within a function with global won't necessary work.

In our integration tests, we use multiprocessing.Value - https://docs.python.org/3.6/library/multiprocessing.html#sharing-state-between-processes, see e.g. https://github.com/plotly/dash/blob/f958d9e0910a860cc5cc0b3b6a98a8f205c29d6a/tests/integration/test_render.py#L325

I think only primitive data types are supported, so you might need to serialize back and forth into strings.

[emmanuelle]

Thanks @chriddyp I'll look into this. It would be a great feature for users who want at the same time to process data in a notebook and to benefit from the rich interactivity of a Dash app.