Add support for OpenAPI generated clients

[R0Wi]

Hi, I'm currently developing a new External App as alternative OCR backend (see https://github.com/R0Wi-DEV/workflow_ocr_backend). It's using the NC framework to build a simple REST API. I noticed that the core framework FastAPI has built in support to create an OpenAPI specification. This spec can be used pretty easily to generate a PHP Client, which in turn could be used in any Nextcloud "native" app.

I can see that the only supported way of communicating with ExApp's currently goes through the PublicFunctions class which does all the heavy lifting like getting the ExApp's url and also adding authentication headers to the request.

Would it be feasible to add support to auto generated clients as well? I think this would make developers life much easier 😄

You can find an example for a generated client here: https://github.com/OpenAPITools/openapi-generator/tree/master/samples/client/petstore/php/OpenAPIClient-php

Looking forward to your feedback. Please let me know if I can contribute anything if needed.

[oleksandr-nc]

Thank you for your interest in AppAPI and for developing ExApp - we are very pleased :)

Your idea of describing ExApps endpoints using OpenAPI is very good idea - we thought about it.

It is worth noting that ExApps can also be accessed via AppAPI proxy (which uses these public API functions of AppAPI).

In general, perhaps in the near future(NC32?) we want to provide an alternative to AppAPI proxy and support WebSockets/QUIC in ExApps, so that each ExApp is accessible via URL of the format: nextcloud.com/exapps/{appid}

After that, we would like to work on OpenAPI support for ExApps, as with possbile new proxy way their endpoints can be called not only from PHP code, but from outside, like OCS API in Nextcloud.

I can’t say more for now, so as not to promise something that might not end up being there, but in 2-3 weeks I’ll be able to say more precisely.

Also, if you have any other requests/questions - feel free to ask us.

[R0Wi]

Hi @oleksandr-nc, thanks for your kind response - much appreaciated. In general I really like the idea behind the ExApp concept, it opens many new possibilities. So if there's anything I can support you with (also taking over some parts of development), just let me know. I would be happy to assist you 😃

We can let this topic rest for the time being and see, what the future brings. Just generally speaking: if you're developing an ExApp and you want to integrate it into Nextcloud, it would be awesome to have some auto-generated API client with strict type support.

Maybe one last question out of curiosity: you mentioned the "AppAPI proxy". If I understand you correctly, this proxy is already available? I'd love to get some insights to this product but unfortunately I wasn't able to find anything in the docs. Maybe you could provide a link where I can find more info about this?

[oleksandr-nc]

Maybe one last question out of curiosity: you mentioned the "AppAPI proxy". If I understand you correctly, this proxy is already available? I'd love to get some insights to this product but unfortunately I wasn't able to find anything in the docs.

Here is this part in the documentation:

https://docs.nextcloud.com/server/latest/developer_manual/exapp_development/tech_details/api/routes.html

The applications that use it are already Flow and Visionatrix

So if there's anything I can support you with (also taking over some parts of development), just let me know. I would be happy to assist you 😃

Yes, we will be glad to hear from you as well.

If you are missing something in AppAPI or have an idea on how to improve something (besides the current OpenAPI idea), we are always glad to discuss each topic in a separate issue/discussion - and if there are no objections on how to implement some feature, then we will always be glad to have pull requests.

[oleksandr-nc]

Just a quick update: if everything goes well, starting with Nextcloud 32, ExApps will get websockets support and will be accessible via URLs nc-instance-url.com/exapps/{appid}

and after that we can make normal OpenAPI documentation