ganeti.rapi.rlib2

PUT or POST?

According to RFC2616 the main difference between PUT and POST is that POST can create new resources but PUT can only create the resource the URI was pointing to on the PUT request.

In the context of this module POST on ``/2/instances`` to change an existing entity is legitimate, while PUT would not be. PUT creates a new entity (e.g. a new instance) with a name specified in the request.

Quoting from RFC2616, section 9.6:

  The fundamental difference between the POST and PUT requests is reflected in
  the different meaning of the Request-URI. The URI in a POST request
  identifies the resource that will handle the enclosed entity. That resource
  might be a data-accepting process, a gateway to some other protocol, or a
  separate entity that accepts annotations. In contrast, the URI in a PUT
  request identifies the entity enclosed with the request -- the user agent
  knows what URI is intended and the server MUST NOT attempt to apply the
  request to some other resource. If the server desires that the request be
  applied to a different URI, it MUST send a 301 (Moved Permanently) response;
  the user agent MAY then make its own decision regarding whether or not to
  redirect the request.

So when adding new methods, if they are operating on the URI entity itself, PUT should be prefered over POST.