WebDAV - a set of extensions and add-ons to the HTTP protocol that support collaborative work on file editing and file management on remote servers.
Implement in PHPRunner projects (same as REST API integration) make ability read write update folders and files from cloud servises as Dropbox Yandex Disk and so on.
Example ajaxbrowser.
Connect and directly manipulate folders and files of almost any cloud service and directly read / write a file from a web page.
CalDAV - Allowing a client to access scheduling information on a remote server.
vCard Extensions to WebDAV (CardDAV) is an address book client/server protocol designed to allow users to access and share contact data on a server.
In fact, we can use sources WebDAV as a dynamic server file database, CardDAV as a dynamic Client database, and CalDAV as a dynamic event database.
The protocol is already quite old. MS SharePoint works on this protocol.
If you use Synology NAS this protocol makes it extremely easy and fast to provide your internal collaboration work to frontend in web applications.