Add xeus-python services

[martinRenou]

Adding a service worker globally usable by all xeus-python kernels for sleeping.

Ideas for xeus-python services usage:

• make the requests Python package work with this?
• make the input blocking?
• make the with open('file.txt') work with this by requesting to the browser local storage?

This should probably be upstreamed to jupyterlite so that it's usable by all kernels

[davidbrochart]

• make the requests Python package work with this?

From this discussion it seems that it's not possible.

[martinRenou]

Why do you say not possible?

[davidbrochart]

From what I read:

"Well, these docs make it seem like it should be possible, but pyodide's open_url() explicitly says it doesn't support binaries--I assume for a good reason.

I ran into this same issue last week trying to make a drop-in to replace the use of requests in my siphon library so that I could get some other protocol working. I came to the conclusion that async is the only option here, which I'm guessing is why we haven't seen a simple requests-replacement."

[DerThorsten]

@davidbrochart could you specify what kind of binaries are not working? Before reading this thread I actually tried to write a simple request replacement based on synchronous XMLHttpRequest. And it seems that for GET request most things I tried are working.

[DerThorsten]

"Well, these docs make it seem like it should be possible, but pyodide's open_url() explicitly says it doesn't support binaries--I assume for a good reason.

I think the good reason is that they must assume that open_url is not only used from a worker, but also from the main thread, where blocking is not so fine. On the main thread sync XMLHttpRequest are even deprecated.

Since we always run things in a worker with xeus-python, it could be fine to XMLHttpRequest for binary data...But at the end of the day, I have not that much knowledge about js/browser stuff :)

[davidbrochart]

Thanks for clarifying @DerThorsten, great to know that when running from a worker everything works fine.

[martinRenou]

Closing this as it's not relevant anymore. JupyterLite now provides a service worker for file access, we have a decent sleep implementation for now, and it might be better to implement a blocking input with sharedarraybuffer when it's available.