REST service, Create request with POST, which response codes 200 or 201, what content

Question

Suppose I write a REST service whose intent is to add a new data item to a system.

I plan to POST to

http://myhost/serviceX/someResources

Suppose that works, what response code should I use? And what content might I return.

I'm looking at the definitions of HTTP response codes and see these possibilities:

200: Return an entity describing or containing the result of the action;

201: which means CREATED. Meaning *The request has been fulfilled and resulted in a new resource being created. The newly created resource can be referenced by the URI(s) returned in the entity of the response, with the most specific URI for the resource given by a Location header field. The response SHOULD include an entity containing a list of resource characteristics and location(s) from which the user or user agent can choose the one most appropriate. The entity format is specified by the media type given in the Content-Type header field. *

The latter sounds more in line with the Http spec, but I'm not at all clear what

The response SHOULD include an entity containing a list of resource characteristics and location(s)

means.

Recommendations? Interpretations?

Answer 1

http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.19

It's just a colon delimited key-value.

ETag: "xyzzy"

It can be any type of text data - I generally include a JSON string with the identifier of the item created. The ease of testing alone makes including it worthwhile.

ETag: "{ id: 1234, uri: 'http://domain.com/comments/1234', type: 'comment' }"

In this example, the identifier, the uri, and type of the created item are the "resource characteristics and location".

Answer 2

I think atompub REST API is a great example of a restful service. See the snippet below from the atompub spec:

POST /edit/ HTTP/1.1
Host: example.org
User-Agent: Thingio/1.0
Authorization: Basic ZGFmZnk6c2VjZXJldA==
Content-Type: application/atom+xml;type=entry
Content-Length: nnn
Slug: First Post

<?xml version="1.0"?>
<entry xmlns="http://www.w3.org/2005/Atom"&gt;
  <title>Atom-Powered Robots Run Amok</title>
  <id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
  <updated>2003-12-13T18:30:02Z</updated>
  <author><name>John Doe</name></author>
  <content>Some text.</content>
</entry>

The server signals a successful creation with a status code of 201. The response includes a Location header indicating the Member Entry URI of the Atom Entry, and a representation of that Entry in the body of the response.

HTTP/1.1 201 Created
Date: Fri, 7 Oct 2005 17:17:11 GMT
Content-Length: nnn
Content-Type: application/atom+xml;type=entry;charset="utf-8"
Location: http://example.org/edit/first-post.atom
ETag: "c180de84f991g8"  

<?xml version="1.0"?>
<entry xmlns="http://www.w3.org/2005/Atom"&gt;
  <title>Atom-Powered Robots Run Amok</title>
  <id>urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a</id>
  <updated>2003-12-13T18:30:02Z</updated>
  <author><name>John Doe</name></author>
  <content>Some text.</content>
  <link rel="edit"
      href="http://example.org/edit/first-post.atom"/&gt;
</entry>

The Entry created and returned by the Collection might not match the Entry POSTed by the client. A server MAY change the values of various elements in the Entry, such as the atom:id, atom:updated, and atom:author values, and MAY choose to remove or add other elements and attributes, or change element content and attribute values.