anchor.diff:          "type" : "Type fo the view"
       }
   
  +`ADD_VIEW` event is sent by a producer when a view is created.
  +`READ_VIEW` event is sent to a consumer when this consumer is connected to an `Organization`.
  +Only views related to the `Organization` are sent.
  +	
   *organization*
   
  -The organization `tag` owning the view.
  +The organization `id` owning the view.
   	
   *name*
   
  
positive.code:     }
  
  * `unit`: the time unit that corresponds to the group level of the time series from year to minute. This field is mandatory. Possible values are `year`, `year/month`, `year/month/day`, `year/month/day/hour`, `year/month/day/hour/minute`.
  * `category`: the category `tag` defining how `Artifact` must be grouped. This field is mandatory.
  * `preferences.color`: an array where each object describes the preferred color to represent a category. Each object has a `label` attribute for the category label and a `value` for the color to apply.
  * `prefereces.chart`: a string indicated the chart displaying the data. The possible values are managed by the user interface.
  
  ==== event = 'REMOVE_VIEW'
  
  The `REMOVE_VIEW` event for an `Organization` has a `data` attribute associated to an empty value.
  In fact, the event simply indicates that a view identified by the event `tag` has been removed.
  Therefore, no more information than the `tag` is required to identify the removed view.
  
  === Artifact
  
  
negative.code: 
  * `from`: The min date of `Artifact`. Must be a timestamp in milliseconds. The value is mandatory.
  * `to`: The max date of `Artifact`. Must be a timestamp in milliseconds if defined. The value can be `undefined`, `null` or `false`. In this case no max date is applied.
  * `category`: The category `id` that will be used to read the timestamp from the artifact. Must be a timestamp in milliseconds if defined. The value can be `undefined`, `null` or `false`. In this case the event timestamp will be used. 
  
  *filters*
  
  Optional filters in addition to the period that are applied on the `Artifact` when selecting the data.
  `filters` value is an array of complex object with two attributes:
  
  * `category`: the category `id` that must be used to filter the `Artifact`. The value is mandatory.
  * `value`: the particular category label that must be associated to the `Artifact`. The value can be `undefined`, `null` or `false`. In this case any value is accepted since the category exist in the `Artifact`.
  
  *type*
  