Example responses from CKAN API: http://test.ckan.net/api/2/rest/package/ec9cb930-d15f-441f-a1e1-36f4d5df19bf

get-package-response.txt

HTTP/1.1 200 OK
Date: Thu, 07 Jul 2011 15:39:32 GMT
Server: Apache/2.2.14 (Ubuntu)
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: POST, PUT, GET, OPTIONS
Access-Control-Allow-Headers: X-CKAN-API-KEY, Content-Type
Pragma: no-cache
Cache-Control: no-cache
Content-Length: 754
Content-Type: application/json;charset=utf-8

{ "author" : "",
  "author_email" : "",
  "ckan_url" : "http://test.ckan.net/package/my-test-package",
  "extras" : { "Custom" : { "key" : "value" } },
  "groups" : [  ],
  "id" : "ec9cb930-d15f-441f-a1e1-36f4d5df19bf",
  "license" : null,
  "license_id" : "",
  "maintainer" : "aron",
  "maintainer_email" : "",
  "metadata_created" : "2007-04-10T21:19:38",
  "metadata_modified" : "2011-07-07T15:25:43.722256",
  "name" : "my-test-package",
  "notes" : "Heading\r\n===\r\nThis _is_ some text",
  "notes_rendered" : "<h1>Heading</h1>\n<p>This <em>is</em> some text\n</p>",
  "ratings_average" : null,
  "ratings_count" : 0,
  "relationships" : [  ],
  "resources" : [  ],
  "revision_id" : "688d33fb-5629-4ab3-9f59-a649fc7caa00",
  "state" : "active",
  "tags" : [ "test-tag" ],
  "title" : "My Test Package",
  "url" : "",
  "version" : ""
}

put-package-response.txt

{ "author" : "",
  "author_email" : "",
  "extras" : [ { "id" : "43d46aa3-be0a-4178-b1b9-99d9c5c58417",
        "key" : "Custom",
        "package_id" : "ec9cb930-d15f-441f-a1e1-36f4d5df19bf",
        "revision_id" : "ba6c0a3f-4685-47f5-86c1-4e3092c93bf7",
        "revision_timestamp" : "2011-07-06T13:12:08.664808",
        "state" : "active",
        "value" : "{\"key\": \"value\"}"
      } ],
  "groups" : [  ],
  "id" : "ec9cb930-d15f-441f-a1e1-36f4d5df19bf",
  "license_id" : "",
  "maintainer" : "aron",
  "maintainer_email" : "",
  "name" : "my-test-package",
  "notes" : "Heading\r\n===\r\nThis _is_ some text",
  "relationships_as_object" : [  ],
  "relationships_as_subject" : [  ],
  "resources" : [  ],
  "revision_id" : "688d33fb-5629-4ab3-9f59-a649fc7caa00",
  "revision_timestamp" : "2011-07-06T10:37:50.182894",
  "state" : "active",
  "tags" : [ { "id" : "600dc72e-6127-4704-b801-bee00474ec0c",
        "name" : "test-tag",
        "revision_timestamp" : "2011-07-06T09:09:21.578034",
        "state" : "active"
      } ],
  "title" : "My Test Package",
  "url" : "",
  "version" : ""
}

GET Request:

$ curl -i http://test.ckan.net:80/api/2/rest/package/ec9cb930-d15f-441f-a1e1-36f4d5df19bf

PUT Request:

$ curl -i -XPUT -d'{"tags": ["test-tag"]}' -H"X-CKAN-API-KEY: tester" -H"Content-Type: application/json" http://test.ckan.net:80/api/2/rest/package/ec9cb930-d15f-441f-a1e1-36f4d5df19bf

In the PUT response each tag in the "tags" array is represented as an object rather than a string. This is the same for the "extras" key where extras is an array of objects rather than a single object.