The software architecture miss coherence and structure

[icarta-l]

Hi! I would like to refactor the codebase using a Clean Architecture, packaged by components and feature approach.

I was advised to open an issue on GitHub to try and see if I could talk with the Nextcloud developers about it. I will try to be brief and concise. I realise that this might take some time and efforts, so I am more than willing to discuss the topic with anyone interested.

The project

I would like to isolate small parts of the codebase either used in marginal features or very localised instructions that could wait being refactored before going through subsequent changes by other maintainers.

I would like to:

• Rewrite the code by gathering sparse pieces in main or otherwise distinguishable components;
• Separate the different feature of each components into its own package inside the component;
• Use the Clean Architecture layers to enforce a strong separation of concerns: Main, Controller, Use Case and Entity;
• Rely on feature-level, integration and end-to-end tests as much as possible.

The idea would be to localise the effort in the hope of making it easier with time to transition, pieces by pieces, to a more coherent yet modular architecture.

I hope this is not a duplicate and that it might be useful.

[provokateurin]

Can you go a bit more into detail of how the new architecture would look like?

I think such big changes are impossible to make for multiple reasons, so you should not waste your time. Of course you can submit PRs to improve the situation and we'll happily review them, but the main problem is that we have many stability guarantees that make breaking changes impossible (which is quite frustrating as I can tell you from my own experience).

[icarta-l]

Sure!

I appreciate the fact that you are asking me about the architecture even though you told me it is impossible to do. I hope you do not feel like you are losing your time on this issue.

If that is okay with you, I will make a small pull request to exemplify what I am trying to propose. Maybe it won't clash too hard with the stability guarantees in place.

Thanks for your time.

[icarta-l]

I have made a small pull request to present a few class diagrams written in Markdown files, encapsulated by plantuml blocks.

It might be a lot of information and pieces to gather. I am more than willing to talk about the architectural redesign in a more direct medium to clarify doubts, questions and anything that might come up while reading the files.

For this pull request, I focused on the oauth2 application. I chose it because I wanted to present the structure using a small part of the application. It might not be the most relevant part to redesign right now but I hope it still serves as a good example. Given the small sample I chose, it shows more of a strong separation of concerns than a general redesign of the whole codebase.

I have written a readme.md file along with the other Markdown files to hopefully make the new architecture clearer. They can all be found inside the oauth2/lib/diagrams repository.

I hope this brings value.

Here is the pull request: #60487

[solracsf]

This would be a major architectural shift for Nextcloud with an existing service layer, touching domain extraction, use case layers, repository patterns, controller adapters, DTOs, value objects, test reorganization, and documentation updates.

[icarta-l]

Thank you @solracsf to take the time to consider my pull request, especially on a weekend.

I am not sure what you mean or intend to say with your previous comment.

Let me explain: when you write

This would be a major architectural shift for Nextcloud

I understand several things:

1. If we were to adopt it systematically for all features, it would mean rewriting everything;
2. If we apply it locally for a specific Nextcloud application or a feature, we would need to document the specific architecture for this localised change, which might clash with Nextcloud's existing architecture;
3. No matter how localised or scoped, it would be a big change of paradigm as I do not see how Nextcloud's current architecture and best practices could merge with this approach;
4. I am just pointing out that this could potentially be a big change.

Could you clarify it for me?

[solracsf]

1 to 4? 😆

What i mean is: sure, there is room for improvement in some areas, but a whole rewrite would mean a shift in architectural decisions and, as @provokateurin pointed out, breaking changes are very difficult to adopt.

But kudos for pointing this out. 🍾