App RFID LLRP Inventory - Location Aliases

Every device(reader) + antenna port represents a tag location and can be assigned an alias such as Freezer, Backroom etc. to give more meaning to the data. The default alias set by the application has a format of <deviceName>_<antennaId> e.g. Reader-10-EF-25_1 where Reader-10-EF-25 is the deviceName and 1 is the antennaId.

To get the list of LLRP devices or readers connected, send GET to the /api/v3/readers endpoint.

Example Get list of connected readers

curl -o- localhost:59711/api/v3/readers

{
  "Readers": [
    "SpeedwayR-10-EF-25"
  ]
}

An alias can be configured for each Reader/Antenna combination.

Configuring the Aliases

Via configuration.yaml (before deployment)

If you already know the alias values you would like to use before deployment, they can be defined in your configuration.yaml file. There is a section called Aliases under the AppCustom section that is defaulted to empty.

Set the default alias as the key, and the new alias as the value you want.

Example Aliases configuration

Aliases:
  Reader-10-EF-25_1: "Freezer"
  Reader-10-EF-25_2: "Backroom"

Aliases Configuration in Config Provider (aka Consul)

If an existing Aliases folder key (even if empty) is found in Config Provider, nothing is done. Data in Config Provider will be left as-is.

If no existing Aliases folder key is found in Config Provider: - If an Aliases section is not present or is empty in the user's YAML file, nothing will be done or added to Config Provider. - If an Aliases section is present and contains data, this data will be uploaded to Config Provider.

Overwrite Config in Config Provider (During Development)

During development, the user also has the option to pass the -o/--overwrite command line flag to the service. In addition to what EdgeX normally does when this is passed, the Aliases are read from the YAML file and uploaded to Config Provider, overwriting existing Aliases with the same key.

Note

One thing to be aware of however is that the Aliases are treated as Key/Value pairs so any Alias key in Config Provider that is not present in the YAML file will not be deleted from Config Provider. Read below for an example scenario.

Scenario

Config Provider already contains the following key/values: - app-rfid-llrp-inventory/AppCustom/Aliases/Reader-10-EF-25_1 = POS - app-rfid-llrp-inventory/AppCustom/Aliases/Reader-20-20-20_1 = Store

The user passes -o/--overwrite flag, with the following YAML:

    Aliases:
      Reader-10-EF-25_1: "Freezer"
      Reader-10-EF-25_2: "Backroom"

Outcome

• Reader-10-EF-25_1 already exists with a value of POS and will be overwritten to Freezer.
• Reader-10-EF-25_2 is new and will be added as expected with value Backroom.
• Reader-20-20-20_1 is not present in the YAML file, but was pre-existing in Config Provider. This value will be left alone.

This results in the following key/value pairs existing in Config Provider: - app-rfid-llrp-inventory/AppCustom/Aliases/Reader-10-EF-25_1 = Freezer - app-rfid-llrp-inventory/AppCustom/Aliases/Reader-10-EF-25_2 = Backroom - app-rfid-llrp-inventory/AppCustom/Aliases/Reader-20-20-20_1 = Store

Note

There is a Config Provider config watcher for the AppCustom section that notifies the app of changes. This config watcher will load all the aliases from Config Provider on startup.

Via Config Provider (after deployment)

Users can also configure the aliases using Config Provider. This can be achieved via Config Provider’s UI or CLI. This can be done regardless of whether configuration.yaml specified initial aliases or not.

Setting Alias via Config Provider UI

• If one does not exist, create a folder named Aliases under [Service Root][http://localhost:8500/ui/dc1/kv/edgex/v3/device-rfid-llrp/AppCustom/]. A folder is created by ending the key with a / like so: Aliases/

• Add Key Value pairs. Key is the default alias which is <deviceName>_<antennaId>. The value must be the alias value. Examples of KV pairs:
  • Speedway-10-EF-25_1: Freezer
  • Speedway-10-EF-25_2: Backstock

Everytime the user creates/updates the Aliases folder, the configuration changes apply to the application dynamically, and the updated alias can be seen under tag location (location_alias)

Send GET to the /api/v3/inventory/snapshot endpoint to see the changes.

Inventory Snapshot with new location name

curl -o- localhost:59711/api/v3/inventory/snapshot

 [
   {
     "epc": "30143639f8419145db602154",
     "tid": "",
     "location": {
       "device_name": "SpeedwayR-10-EF-25",
       "antenna_id": 1
     },
     "location_alias": "Freezer",
     "last_read": 1601441311411,
     "last_arrived": 1601441265669,
     "last_departed": 0,
     "state": "Present",
     "stats_map": {
       "SpeedwayR-10-EF-25_1": {
         "last_read": 1601441311411,
         "mean_rssi": -54.25
       }
     }
   }
 ]     

Setting Alias via Config Provider CLI

Aliases can also be set via Consul API. Ex:

curl \
--request PUT \
--data "Freezer" \
http://localhost:8500/v1/kv/edgex/appservices/2.0/app-rfid-llrp-inventory/AppCustom/Aliases/SpeedwayR-10-EF-25_1