6.2 Use Case: Query parking sites in the vicinity (UC1)

Use Case 1 (UC1) is about querying for parking sites within a given geographic area, e.g. around the current location of a car. Figure 6.2-1 visualizes this scenario.

Figure 6.2-1: UC1 - Query parking sites in the vicinity

The basis for modelling the information required for this use case is the NGSI-LD compatible Smart Data Model[i.5] on Parking, which makes a distinction between OffStreetParking and OnStreetParking. As this distinction is not relevant for our use case, we restrict the example on a number of common NGSI-LD properties: - address - allowedVehicleType - availableSpotNumber - category - chargeType - location

The query for parking sites within a given geographic area, e.g. around the current location of a car:

GET /ngsi-ld/v1/entities/?type=OnStreetParking,OffStreetParking&geoproperty=location&georel=near%3BmaxDistance==1000&geometry=Point&coordinates[-3.8040616,43.4631649]

Accept: application/json
Host: localhost:9090
Link: <http://example.org/myContext.jsonld>; rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"

It queries for all NGSI-LD Entities of type OnStreetParking or OffStreetParking, and geographically scopes it with the circle around the geographic point with coordinates -3.8040616,43.4631649 and a radius of 1000m.

Excerpt of result:

[{
    "id": "urn:ngsi-ld:OnStreetParking:santander:daoiz_velarde_1_5",
    "type": "OnStreetParking",
    "allowedVehicleType": {
        "type": "Property",
        "value": [
            "car"
        ]
    },
    "availableSpotNumber": {
        "type": "Property",
        "value": 3,
        "observedAt": "2018-09-12T12:00:00Z"
    },
    "category": {
        "type": "Property",
        "value": [
            "blueZone",
            "shortTerm",
            "forDisabled"
        ]
    },
    "chargeType": {
        "type": "Property",
        "value": [
            "temporaryFee"
        ]
    ...

The advantages for the application are the following: - Application can reuqest information by specifying what it needs ("parking sites in the vicinity") - Application gets result with a single request (unless paging is required due to number of results) - Application can gegographically scope the request

In order to do this, the application needs to know the following: - Data model: - type: OnStreetParking, OffStreetParking - GeoProperty name: location - its current location - Root URL: localhost:9090