[Edit : now CSOM ships with the possibility to specify versioning settings]
Sometimes, despites of all the available APIs, you find yourself stuck on making very basic things. For instance, I recently had to study the feasibility of automating the creation of OneDrive for business sites with some requirements.
One of them was simply to predefine the number of major versions to 20. Nor CSOM, nor REST APIs make this possible…neither, the recent Office SDK does. So, what’s left? Well, maybe making a list template, taking a backup of it and provision it later on the newly created personal sites, create a list instance of it, all via CSOM. It’s surely possible. Yes, but the list template doesn’t take into account IRM settings (which was another requirement). Also, list templates cannot be applied to the default library nor to existing lists…making them useless at some occasions.
So, what’s left? Well, the good old URL protocol of course, namely the RPC protocol which is deprecated but still very useful :). If you happen to be stuck in any automation process with OD4B or more globally, with SharePoint online, think of that guy, you might spare a lot of time as it’s still capable of many different things. Also, it’s deprecated yes but seing how SharePoint Designer and Office Clients still intensively use it, I doubt it will be removed very soon.
Also, not so long ago, I had to perform mass provisioning on a on-premises environment and I could chose between REST & RPC. I first built everything in REST and it was working but damn slow. I couldn’t afford the slowness because my process had to take place during a very limited time frame everyday. I then used the RPC protocol to do the exact same thing and guess what, it was more or less 10 times faster…
So, nothing really new here but I don’t see often the combination of RPC & SharePoint online although it can still offer services that all our recent APIs can’t do!