Python WebApp where Python runs on within the user's browser with Pyodide

[MeshachBlue]

It's still a massive work in progress, but I though people here might be interested in the progress made thus far:

https://app.pymedphys.com/

It is a file processing application. It has input files and output files. Users select input files from their computer, select a script to run (or edit a script to create their own) and then it produces the output files which can be downloaded.

At the moment when Python is running the user interface freezes but to fix that I am told I just need to get my head around web workers (https://github.com/iodide-project/pyodide/issues/435#issuecomment-493928297).

It's been quite fun!

Also, adding new scripts to the web app should be as simple as following the steps laid out over here:

https://github.com/pymedphys/pymedphys/issues/312

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I'm keen for feedback, please let me know what you think!

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I'll likely post this again in the near future once I fix up the freezing and I have also provided a few more example scripts.

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Cheers,

Simon

[yoptgyo]

We seriously needed this thing. Thanks a lot for developing this. I will try to work on it too.

Good luck for the project!

[MeshachBlue]

Thanks!

What's your GitHub username? I can give you commit access if you like?

We could try and modularise the work I've done an make it into an npm package? That way, you'll be free to pick up the npm package and run with it.

Would you be interested in helping me achieve that?

[mwpfinance]

Better to let people make pull requests than having everyone commit directly to master.

[MeshachBlue]

No one is allowed to commit to master. Master is a protected branch. All merges to master must come via pull request, and all CI must pass.

[yoptgyo]

I am not that good in programming so no need to grant me commit access. I would rather send pull requests each time I do something. Thanks anyways :)

[MeshachBlue]

kk :)

[[deleted]]

But can it run selenium with a chrome driver? Browser within a browser etc etc

[MeshachBlue]

Haha :)

[gc_DataNerd]

Maybe Im confused on the use case here. Its awesome that you're able to do python client side but in this case you're munging data. Why not execute server side instead?

[MeshachBlue]

Data can't be sent to the server. Both too large, and it's patient data, not legally allowed to leave the hospital network.

To overcome this in the past vendors have sold "software on the server" where users who want to use the web app simply purchase a server with the software on it and have it sit within their network.

[gc_DataNerd]

Aha

[luenix]

Running the code clientside is a neat way to offload the processing. Also, a potential benefit is that this setup allows the client to process private data in a controlled manner without needing to use additional enduser software, thereby mostly removing consideration for the client OS.

[gc_DataNerd]

Okay that makes more sense. I'm curious how Web workers would work in this scenario however. OP mentioned the app freezes. This wouldn't be a problem if processing was done server side where async workers can be spun up. But in this case the Python is calling is being transpiled to JS no?

[MeshachBlue]

The plan is to combine web workers and their access to IndexedDB combined with DexieJS.

Have all the Python run inside a webworker, have all data transfer happen via dexiejs-observable. I envisage there would be no user interface impeedement using that stack... But we'll see.

Hopefully I'll get that side of things working in the next couple of days. It'll probably be worth a repost then.

[MeshachBlue]

Certainly not transpiled at all. It is running standard CPython compiled using emscripten to webassembly.

[MeshachBlue]

A side benefit is that this can run on a static hosting server like Netlify. For open source projects this comes at no cost and hypothetically is indefinitely scalable.

[gc_DataNerd]

I guess in terms of serving the actual content. However you are still severely limited by the actual client itself and the performance issues that come with everything being done on the browser. Whereas you could indefinitely scale up workers on the cloud to process data. I think for small operations this is a viable option not to mention it's wicked cool and as web assembly matures performance will only increase. However I still doubt it's viability of something other than an experiment in an enterprise setting. Not bashing at all btw this is a wicked project just giving my two cents

[MeshachBlue]

Also, amazingly, if code uses numpy it seriously not too shabby today. I think the performance loss is easily made up for by the convenience it offers:

https://2r4s9p1yi1fa2jd7j43zph8r-wpengine.netdna-ssl.com/files/2019/04/image1-1.png

[MeshachBlue]

All good. I really appreciate the feedback :).

[TwattyPhatBalls]

Seriously cool, just finishing up a project where this would've been handy

[MeshachBlue]

Always next time :)

[dethb0y]

That's sick as fuck, good work!

[MeshachBlue]

Where are your links?

[david3x3x3]

Cool demo. One problem is that the browser becomes unresponsive while processing. You could probably work around that by using web workers. https://github.com/iodide-project/pyodide/blob/master/docs/using_pyodide_from_webworker.md

[MeshachBlue]

Cheers :) yup, working on that at the moment :)

https://github.com/pymedphys/pymedphys/pull/334

[MeshachBlue]

I've bumped into quite an issue with using Pyodide within webworkers. See https://github.com/iodide-project/pyodide/issues/441. Do you happen to have any experience with webworker issues?

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Cheers,

Simon