Moving application (add-in) from SharePoint Online to Server?

Question

I know there are two basic options:

• SharePoint Server - building your own infrastructure, installing server etc. (works in Intranet)
• Share Point Online - using the infrastructure provided by Microsoft.

I wonder if it's guaranteed that if I develop solution/add-in for Share Point Online, it can be moved (used) and will always work on SharePoint Server?

Are there any restrictions (e.g. online or server version has less functionalities, not support Web Parts, some programming language or something like that), or differences between those two from developer point of view (and not the infrastructure manager)? Or moving your add-in from SharePoint Online to Server is trivial action (changing target)?

Answer 1

SharePoint Ads-Ins are designed to be compatible with multiple environments. Think of the SharePoint App Store - companies an individuals publish apps in the store so that others can use them in their environments. From a technical perspective, Add-Ins use CSOM (Client Site Object Model), which is compatible with both SharePoint Online and SharePoint Server. One word of advice I would give is to decide what version of SharePoint Server you plan to install. If it is SP 2016, make sure to use the 2016 (16 or 16.1) CSOM assemblies. This will afford a seamless transition between SP Online and SP Server. If you go to SP Server 2013, then use CSOM 15. This version of CSOM works in SPO and SharePoint 2013. Don't use CSOM 16/16.1 for SharePoint 2013 - there are certain methods and properties not available in SP 2013.

Otherwise, don't hard-code URLs or credentials into your code - this will make it not work when you switch between environments. Also don't hard-code things into the app which would not be transferred over in a migration - like GUIDs of objects (lists, items, webs, sites, etc), and just make the code as dynamic as possible.

I'm sure there is more I am not thinking of, but this is most that I can think of