write trial to read-only calendar blocks complete sync

[davvi]

Hi,

the following is a more advanced usage of DAVDroid, I have to admit.
We are using multiple Androids on the same server (Synology), with multiple calendars.
Each member has his own calendar with read+write access, but only read access to the calendars of the other members (to prevent deleting events of the others by accident).

Sometimes on creation of a new event (in acalendar+), some member does not take care which calendar to use and selects a calendar of somebody else. This leads to a write error on server side, of course, and therefore to a sync error in DAVDroid.

Unfortunately, the complete sync is blocked then… until the correct calendar is selected.

As far as I see, there is no option to select “continue sync on errors”. Why not? Is there a design reason not to implement this? Or was this just not requested yet?

Is there a better way to deal with read-only calendars?

Thanks.

[rfc2822]

@davvi This is a Synology bug, see Synology CalDAV reports write permissions for read-only calendars.

As far as I see, there is no option to select “continue sync on errors”. Why not? Is there a design reason not to implement this? Or was this just not requested yet?

Synchronization would come into an undefined state if a write operation fails. Also, there may be errors after this operation and because there’s no interactive way to resolve problems (just notifications), there could be dozens and more errors per sync operation. Those masses of error messages would cause irritations on user side and would be hard to debug.

DAVdroid makes a difference between soft errors (I/O errors, sync interrupted etc.) and hard errors (like when the server sends an HTTP error on an important operation) and for safety reasons, DAVdroid stops on hard errors.

Is there a better way to deal with read-only calendars?

If the server reports permissions as read-only (instead of read-write), DAVdroid will recognize this and set the calendar to read-only locally. Then events can’t be changed locally and there won’t be any problems.

[davvi]

@rfc2822 said in write trial to read-only calendar blocks complete sync:

@davvi This is a Synology bug, see Synology CalDAV reports write permissions for read-only calendars.

As far as I see, there is no option to select “continue sync on errors”. Why not? Is there a design reason not to implement this? Or was this just not requested yet?

[…]
for safety reasons, DAVdroid stops on hard errors.

Ok, makes sense. Thanks for your detailed explanation.
So, the only way to deal with it, is:

Is there a better way to deal with read-only calendars?

If the server reports permissions as read-only (instead of read-write), DAVdroid will recognize this and set the calendar to read-only locally. Then events can’t be changed locally and there won’t be any problems.

On Synology, they propose to handle it with file permissions on file server level. That is how I do it.
But I guess this is not what you expect by a server that is capable of “reporting permissions as read-only”, right?
What is the requirement regarding CALDAV communication that I should post towards Synology to support my case? How do you the server expect to report read-only permissions?

Thanks.

[rfc2822]

@davvi We have reported the problem to Synology on 6 Dez 2015 (Synology Support Ticket: #712664). To report read/write privileges, CalDAV uses WebDAV ACL.