anchor.diff:              "temperature"
           ]
   
  -## Standard OMA-NGSI operations [/v2/queryContext]
  +## Context Subscriptions [/v2/entities/{entityId}/subscriptions]
  +
  +A subscription is represented by a JSON object with the following fields:
  +
  +* `id`: Subscription unique identifier. Automatically created at creation time.
  +* `subject` : It s an object that describes the subject of the subscription.
  +* `notification` : It is an object that describes the notification received by the subscriber.
  +* `options` : It is a dictionary which can contain different parameters related to the subscription, including:
  +  * `duration`: Duration of the subscription in ISO8601 format. Infinite if not specified.
  +
  +A 'subject' contains the following subfields:
  +
  +* `entity` : Id or pattern id which identifies the affected entities (optional)
  +* `type` : Type of the affected entities (optional)
  +* `attributes`: List of attributes to be monitored (if not specified it would mean all)
  +* `condition`: Condition that will trigger the notification. It could be 'ONCHANGE' or 'ONTIMEINTERVAL'.
  +By default will be ONCHANGE.
  +* `expression`: Logical the expression on attributes. When its evaluation results in a
  +`true` value the notification will be sent.
  +
  +Entity or type must be present.
  +
  +Please note that at the time of writing the editors are considering different options
  +to model these parameters, thus this is likely to change.
  +
  +A 'notification' object contains the following subfields:
  +
  +* `attributes`: List of attributes to be included in the notification message.
  +If not specified they will be the same as those which are monitored
  +* `callback` : URL that will point to the service which will be invoked when a notification is generated
  +* `throttling`: A period of time (in ISO8601 format) which must ellapse between two consecutive notifications.
  +
  +### List subscriptions [GET /v2/subscriptions]
  +
  +Returns a list of all the subscriptions present in the system
  +
  ++ Response 200
  +
  +        [
  +            {
  +                "id": "abcdefg",
  +                "subject": {
  +                    "entity": "Bcn_Welt",
  +                    "type": "Room",
  +                    "attributes": [
  +                        "temperature"
  +                    ],
  +                    "condition": "ONCHANGE"
  +                },
  +                "notification": {
  +                    "callback": "http://localhost:1234",
  +                    "attributes": ["temperature", "humidity"],
  +                    "throttling": "PT5S"
  +                },
  +                "options": {
  +                    "duration": "PT1M"
  +                }
  +            }
  +        ]
  +
  +### Create a new subscription [POST /v2/subscriptions]
  +
  +Creates a new subscription.
  +The subscription is represented by a JSON object as described at the beginning of this section.
  +
  ++ Request (application/json)
  +
  +        {
  +            "subject": {
  +                "type": "Room",
  +                "attributes": [
  +                      "humidity"
  +                ],
  +                "condition": "ONTIMEINTERVAL"
  +            },
  +            "notification": {
  +                "callback": "http://localhost:1234",
  +                "attributes": ["temperature", "humidity"],
  +                "throttling": "PT5S"
  +            },
  +            "options": {
  +                "duration": "PT1M"
  +            }
  +        }
  +
  ++ Response 201
  +
  +    + Headers
  +
  +            Location: /v2/subscriptions/abcde98765
  +
  +## Context Provider Registration [/v2/registrations]
  +
  +Context Registration allows to associate external services to context data. One of the main
  +use cases of this functionality is the association of Context Providers.
  +
  +A context registration is represented by a JSON object with the following fields:
  +
  +* `id`: Unique identifier assigned to the registration. Automatically created at creation time.
  +* `subject` : It s an object that describes the subject of the registration.
  +* `callback` : URL of the service which is registered. In the case of a Context Provider
  +corresponds to the URL of the provider service.
  +* `options` : It is a dictionary which can contain different parameters related to the registration, namely:
  +  * `duration`: Duration of the registration in ISO8601 format. Default duration is infinite.
  +
  +A `subject` contains the following subfields:
  +
  +* `entity` : Id or pattern id which identifies the affected entities (optional).
  +* `type` : Type of the affected entities (optional).
  +* `attributes`: List of attributes to be provided (if not specified it would mean all).
  +
  +Entity or type must be present.
  +
  +### List registrations [GET /v2/registrations]
  +
  +Lists all the registrations present in the system.
  +
  ++ Response 200
  +
  +        [
  +            {
  +                "id": "abcdefg",
  +                "subject": {
  +                    "entity": "Bcn_Welt",
  +                    "type": "Room",
  +                    "attributes": [
  +                        "temperature"
  +                    ]
  +                },
  +                "callback": "http://localhost:1234",
  +                "options": {
  +                    "duration": "PT1M"
  +                }
  +            }
  +        ]
  +
  +### Context provider registration [POST /v2/registrations]
  +
  +Creates a new registration. This is typically used for associating context providers
  +to certain data.
  +The registration is represented by a JSON object as described at the beginning of this section.
  +
  ++ Request (application/json)
  +
  +        {
  +            "subject": {
  +                "type": "Room",
  +                "attributes": [
  +                      "humidity"
  +                ]
  +            },
  +            "callback":  "http://localhost:1234",
  +            "options": {
  +                "duration": "PT1M"
  +            }
  +        }
  +
  ++ Response 201
  +
  +    + Headers
  +
  +            Location: /v2/registrations/abcde98765
  +
  +
  +## OMA-NGSI Operations [/v2/queryContext]
   
   For the sake of completness here is an enumeration of the OMA-NGSI (9 & 10) operations. Those
   operations will be supported under the 'v2' resource as well.
  
positive.code: 
  + Response 204
  
  ## Entity Attribute [/v2/entities/type/{entityType}/id/{entityId}/attrs/{attrName}]
  
  ### Get attribute data [GET /v2/entities/type/{entityType}/id/{entityId}/attrs/{attrName}]
  
  
negative.code: 
  + Response 200
  
  ## Attribute Value by Entity type and ID [/v2/entities/type/{entityType}/id/{entityId}/attrs/{attrName}/value{?options}]
  
  ### Get attribute data [GET /v2/entities/type/{entityType}/id/{entityId}/attrs/{attrName}/value{?options}]
  
  