json_schema: {
      "$id": "http://foo.bar/images.json",
      "$schema": "http://json-schema.org/draft-04/schema#",
      "title": "images",
      "description": "Universally Unique Identifier",
      "type": "array",
      "minItems": 1,
      "_uniqueItems": true,
      "items": {
          "type": "object",
          "properties": {
              "link": {
                  "type": "string",
                  "format": "uri",
                  "description": "url of the image"
              },
              "alt": {
                  "type": "string",
                  "maxLength": 255,
                  "description": "alt text for image"
              },
              "title": {
                  "type": "string",
                  "maxLength": 255,
                  "description": "Used to caption the image"
              }
          }
      }
  }