I wish OneDrive, Dropbox, etc. had a notion of a Personal Database File System, PDFS. With PDFS if they all shared the same API then you could build a database ontop of the PDFS that syncs to popular file systems.
If both of those things existed you would be able to build apps like LinkedIn such that LinkedIn could just access your PDFS so your profile is actually hosted directly on your PDFS - so if you delete your profile info on your PDFS it's gone from LinkedIn. Of course, this also depends on trusting LinkedIn to not just copy over the contents of your PDFS but that could be handled as well.
>Solid (Social Linked Data) is a web decentralization project led by Tim Berners-Lee, the inventor of the World Wide Web, developed collaboratively at the Massachusetts Institute of Technology (MIT). The project "aims to radically change the way Web applications work today, resulting in true data ownership as well as improved privacy" by developing a platform for linked-data applications that are completely decentralized and fully under users' control rather than controlled by other entities. The ultimate goal of Solid is to allow users to have full control of their own data, including access control and storage location. To that end, Tim Berners-Lee formed a company called Inrupt to help build a commercial ecosystem to fuel Solid.
You have to remember that all of these companies are either part of a large company or a startup. Locking you in is the reason they can justify their stock, their IPO, their exit and their high developer salaries.
So if it's just about protocol to exchange files, SSH and webdav are the de-facto standards for that (FTP has declining popularity).
If we're talking about the semantics of building desktop applications, then i think you're looking for freedesktop.org, although it quite POSIX-centered.
All four of these standards could receive extension proposals for more semantics for specific use-cases. However, Microsoft (who owns linked in) and other evil tech-multinationals will never adopt a standard because that would allow competitors to walk on their turf. Remember when gmail.com chat was federated with Jabber/XMPP until Google pulled the plug?
Microsoft was planning this 20 years ago with WinFS, to be shipped in what became Windows Vista. For many political and technical reasons it never came to pass. Some of the folks working on it went on to work on what became OneDrive though.
> What happens if you set up OneDrive and Dropbox (and Google and Apple) to sync the same folder.
Chaos, potentially. Think about deletes... delete a file from the web UI of one service, its client deletes the file locally, but that same instant the _other_ service sees the missing file and happily restores it, the first client deletes, the second client restores, etc. etc. until you've blown gigabytes and gigabytes of network bandwidth.
In other words, ultimate control needs to be on the client side. You delete from Dropbox, and the local machine marks the file as no longer being backed up by Dropbox but does not delete it. Some UI needs to present to the user: This file is backed up in these services, but not the other one. At that point, the user has the choice of fully removing the file, restoring it to Dropbox, or leaving it alone. They may even decide they don't want it backed up in any service, but want it to remain on the filesystem.
If both of those things existed you would be able to build apps like LinkedIn such that LinkedIn could just access your PDFS so your profile is actually hosted directly on your PDFS - so if you delete your profile info on your PDFS it's gone from LinkedIn. Of course, this also depends on trusting LinkedIn to not just copy over the contents of your PDFS but that could be handled as well.