change the message for module loading

[12rambau]

People complains a lot because of the loading of the app. but non are complaining about the terminal.
The main difference being the message that we display to the end user :

In the terminal case :

Session is starting. This might start a new server, which could take several minutes.

For apps:

Loading...

What would you think about changing the message for app as well ? If the app start super fast, people will be super happy (as like when your plane is supposed to be 2h late and end up being only 1h late) and for the others they will not be surprised if it take time.

[eriklindquist]

Is there nothing in Jupyter / Voila or any module being used by sepal-ui that can help us with a message while the thing is starting? Why does the black screen appear and stay so long? Can we ask the developers of Voila to assist with something as well?

[12rambau]

answer

So first the loading message with the map background is coming from SEPAL so there is there nothing we can really do on the Python side.

Then the black screen is in fact in 2 steps:

1. The actual loading of the notebooks. sometime I see the spinning wheel sometime I don't. That's kinda magic.
2. The loading of the JS. Once every cell is executed on the kernel side, the browser need to render the javascript. Thats' a very long process unfortunately. To put it in a nutshell, what vuetify is doing is writting JS code that rewrite the page by creating new DOM elements. It's costly and long. It can also crash if you add to many maps for ex.

If we display a "init" message (with a print for example) It will shift everything else down and we put lots of effort with @ingdanielguerrero to avoid this padding.

Sum-up:

We may be able to reduce the time of the first step by changing the architecture of the framework (I'm currently doing tests on this matter) but for the second one I don't know. I'll continue asking things to the maintainer of both the voila and the ipyvuetify repo. but changing the displayed message appears to be a painless quick fix to me.