Implement CalDAV-Managed Attachments (RFC 8607)

[AnorBanantje]

Is your feature request related to a problem? Please describe.

Hey, i installed Calendar 4.3.0 (Manual Way) on my Nextcloud server, adding attachments to events through web interface works but when i want to add attachment through aCalendar+ which normally support attachments with davx5.
Attachments are added through aCalendar+ and are available on aCalendar+ but is not synced to nextcloud calendar (Event is synced).

Describe the solution you'd like

DAVx5 support to Extended event properties:
https://manual.davx5.com/integration.html#extended-event-properties

Could be possible to implement attachments synchronisation in this way through DAVx5?

Describe alternatives you've considered

No response

Additional context

No response

[tcitworld]

The page you've linked to refers to DAVx5 <-> Android app compatibility, not DAVx5 <-> CalDAV Server compatibility.

It's unclear from the release notes if DAVx5 has brought RFC 8607 support (see #4251 (comment) and #4251 (comment)). In any case, that's what Nextcloud currently misses, even though #4251 is available.

cc @devvv4ever

[devvv4ever]

Currently we don't have support for Managed Attachments in DAVx5 either. It is however on our "This will definitely come to DAVx5"- to do list :) It was a bit post-poned since we now bundling forces to bring WebDAV (+CalDAV) Push to life first. This is our main goal for the next months.

Attachment support will be on the list after the Push I think. We primarily want to support Managed Attachments, where the server is managing the file. This would be the best way I think and we will get in touch with Nextcloud people to possibly coordinate an implementation for this at maybe the same time as we implement it in DAVx5 so that it can get to people on Android without much delay.

[jakobroehrl]

Maybe it would make sense to add a link to the attached file in the description so on mobile the user can click on the link and open the attachment?

[KaeTuuN]

@devvv4ever Any news/ticket/timeline on that now?

[devvv4ever]

WebDAV Push is on a good way, and we'll probably start on support for attachments after this as our next "bigger" project.

[Toastyyy3]

Sorry to bump but as the last update is about a year old. Is there any progress / precise timeline @devvv4ever ?

[SebastianKrupinski]

Hi Everyone,

Can anyone post a sample calendar event, that was created with DAVx and has an attachment? And I will investigate the possibility of making it work.

[devvv4ever]

Sorry to bump but as the last update is about a year old. Is there any progress / precise timeline @devvv4ever ?

No progress yet, we are still working on finalizing all WebDAV Push related things, which turned out to take longer than expected, sorry. And we have to rewrite large parts of DAVx5 under the hood, additionally. We have not forgotten attachments sync... Can't give any ETA when we can start this.

[Toastyyy3]

@devvv4ever Alright no worries, thank you for the update!

@SebastianKrupinski If I'm not mistaken, Nextcloud itself doesn't support CalDAV managed attachments as of now, right? Are there plans to implement that? So one can download and upload attachments using the native apple calendar app? Or am I missing something?

[tcitworld]

It's unsure if Apple apps are compatible with RFC 8607, even though the RFC was drafted someone working there.

[Toastyyy3]

@tcitworld Funny world. What does that mean regarding Nextcloud?

[tcitworld]

Doesn't really change anything, it's still interesting but there's no hurry to have this in server if no client apps are compatible anyway.

[SebastianKrupinski]

Well this is a yes and no answer.

Yes we kind of do support attachments, at the moment only ics embedded attachments can be saved (by external clients) in the invite itself, but the UI will not recognize those attachments.

No, we do not have a URL based way to add, remove and delete attachments as per RFC 8607.

Example...

BEGIN:VCALENDAR
   VERSION:2.0
   PRODID:-//Example Corp.//CalDAV Server//EN
   BEGIN:VEVENT
   UID:20010712T182145Z-123401@example.com
   DTSTAMP:20120201T203412Z
   DTSTART:20120714T170000Z
   DTEND:20120715T040000Z
   SUMMARY:One-off meeting
   ATTACH;MANAGED-ID=97S;FMTTYPE=text/html;SIZE=59;
    FILENAME=agenda.html:https://cal.example.com/attach/64/34X22R
   END:VEVENT
   END:VCALENDAR

You can see the link in the attachment line. The client would then use this to download the attachment.

Too be fair we kind of already do this with our attachment now, but we use a custom URL that only works internally. This could be converted to a proper URL but the issue would be how to control security of files for external users.