[scim] HTTP Status Code 501

[Shelley <[e-mail]>]

*/Me Endpoint Support*

The SCIM 2 specification indicates that if a service provider does not
support the "/Me" endpoint, it should respond with HTTP 501 [1].

This doesn't seem inline with the HTTP specification, which indicates that
501 is used when the server *does not recognize the request method* [2].

In the case of the "/Me" endpoint, however, the server *does *recognize the
*method* (GET), but simply does not support a representation for the
requested resource, which seems more inline with a *404* [3].

What was the reasoning behind the 501? Given the requirement is a "SHOULD"
recommendation, I'm inclined to return the HTTP standard 404 in my service
provider implementation, instead of the SCIM recommended 501.

*PATCH Operation Support*

The SCIM 1.1 and 2.0 specifications also imply that 501 should be returned
when PATCH is not supported [4]. This also seems to violate the HTTP spec,
if the server recognizes the PATCH method, but simply does not support this
method for the requested resource. Instead, a *405* (Method Not Allowed)
[5] seems more appropriate.

[1] https://tools.ietf.org/html/rfc7644#section-3.11
[2] https://tools.ietf.org/html/rfc7231#section-6.6.2
[3] https://tools.ietf.org/html/rfc7231#section-6.5.4
[4] https://tools.ietf.org/html/rfc7644#section-3.12
[5] https://tools.ietf.org/html/rfc7231#section-6.5.5