Normalized [previously canonical] format

[fgalan]

In order to ease the programming of clients that need a uniform format for attributes, an option could be passed to the GET operations that render that information, so attribute and metadata will be using always an structure with value, type and metadata (in the case of attributes) or value and type (in the case of metadata).

E.g. non-canonical:

         {
            "type": "Car",
            "id": "P-9873-K",
            "colour": "red",
            "speed": {
                "value": 100,
                "type": "number",
                "accuracy": 2,
                "timestamp": {
                    "value": "2015-06-04T07:20:27.378Z",
                    "type": "date"
                }
            }
         }

would be:

         {
            "type": "Car",
            "id": "P-9873-K",
            "colour": {
              "value": "red",
              "type": ""
            }
            "speed": {
                "value": 100,
                "type": "number",
                "accuracy": {
                   "value": 2,
                   "type": "number",
                "timestamp": {
                    "value": "2015-06-04T07:20:27.378Z",
                    "type": "date"
                }
            }
         }

[fgalan]

One possiblity so clients can specify they want the info in cannonical way is to use the cannonical option, e.g.:

GET /v2/entities?options=canonical

[fgalan]

This pseudo-test harness should be taken into account when implementing this issue (only the part related with canonical model):

https://gist.github.com/fgalan/d39b016be45d2591a6e7

[fgalan]

Another posibility for the options parameter would be oma, as the structures returned are close to the one used by the OMA spec, e.g.:

GET /v2/entities?options=oma

[fgalan]

Better terms has been suggested:

• normalized (instead of canonical)
• compact, for meaning the opposed to normalized.

[fgalan]

The changes mentioned in #1259 will implement this in a different way. Closing.