Im working on a Java project that needs to upload files using either REST or CMIS (both services are available). I'm completely new to these APIs and would like to ask which one would be easiest and more straightforward to implement. I can't use external libraries in the project, so I will need to implement the client from scratch.
Note: the only requirement is to upload files.
Thanks in advance.
While I admit that I don't know CMIS, file upload with REST is just classic HTTP file upload where you interpret the path name as indicative of the resource to update or replace. Basic REST usage would have you do (an HTTP) GET (method) as “read the file”, POST as “create the file while picking a new name” (typically with a redirect afterwards so that the client can find out what name was picked), PUT as “create the file with the given name or replace that file's contents”, and DELETE as “delete the file”. Moreover, you don't need to support all those methods; do as few as you want (but it's a good idea to support some GET requests, even if just to let people that their uploads worked).
However, when implementing you want in all cases to try to avoid holding much of the file's data in memory; that doesn't scale. Better to take the time to implement streaming transfers so that you never actually need to buffer more than a few kilobytes. You can certainly do this with REST/HTTP. (You could even do it with SOAP using MTOM, but that's probably out of scope for you…)