Data Operations · NGSI-LD and Stellio

Stellio Subscriptions

The node manages existing NGSI-LD subscriptions of the Stellio context broker: list all subscriptions, read a single one, activate or deactivate it via PATCH and delete it. The operation can be fixed in the dialog or controlled per message via msg.operation. A Browser tab shows all subscriptions with their status directly in the editor.

Subscriptions
Manage
NGSI-LD

Node type: stellio-subscriptions
Package: @htag/node-red-contrib-hypertegrity-ngsi-ld
Inputs / outputs: 1 / 1
Target: Stellio context broker (NGSI-LD)

When to use this node

Subscriptions make the context broker report changes to entities to a receiver, for example a time series database. Over time, subscriptions accumulate that need to be checked, paused temporarily or removed. This node bundles the required operations; new subscriptions are created with Stellio Create Subscription.

Typical use cases are:

Inventory: list all subscriptions of a tenant with entity type, watched attributes and status.
Maintenance window: deactivate a subscription while data is being cleaned up and reactivate it afterwards.
Clean-up: delete orphaned subscriptions by id.

How the node works

Determine operation

msg.operation or the configured action chooses between List, Get, Set Active and Delete.

Send request

The node calls /ngsi-ld/v1/subscriptions via GET, PATCH or DELETE with tenant and Link headers.

Emit response

Response body, status code, headers and, for List, the result count are written into the message.

Result: A subscription list, a single subscription or the result of the change in msg.payload.

The node is message-driven and triggers exactly one request per incoming message. The Browser tab loads up to 100 subscriptions through the admin endpoints of the Node-RED server and allows activating, deactivating and deleting via buttons.

Configuration

The dialog has the tabs Aktion (action) and Browser. All stored fields are on the action tab.

Action tab

Field	Type	Default	Meaning
Name	Text	empty	Display name of the node in the flow. Without a name the node shows `Subscriptions: <action>`.
API URL	Text	`${STELLIO_API_URL}`	Base URL of the broker. Placeholders `${VAR}` are replaced at runtime; empty means fallback to the environment variable `STELLIO_API_URL`.
Tenant	Text	empty	Value of the `NGSILD-Tenant` header. Empty: default tenant of the broker.
Context	Text	see below	JSON-LD context for the `Link` header on List, Get and Set Active.
Aktion (action)	Select	`List`	`List` (all subscriptions), `Get` (single by id), `Set Active` (switch active/inactive), `Delete` (delete).
Limit	Number	`100`	Maximum number for List.
Subscription ID	Text	empty	Full URN for Get, Set Active and Delete, for example `urn:ngsi-ld:Subscription:001`.
Status	Select	`aktiv` (active)	Target state for Set Active: `aktiv` (active) or `inaktiv` (inactive).

Default values of the URL fields:

Context: https://context.${DOMAIN}/main-context.jsonld

Which fields are visible depends on the action: Limit for List, Subscription ID for Get, Set Active and Delete, Status only for Set Active.

Browser tab

Laden (load) lists up to 100 subscriptions with id, description, entity types, watched attributes, q-filter, context and status (active/inactive). Each row offers buttons for details, activate/deactivate and delete (with confirmation).

Changes from the editor

Activating, deactivating and deleting in the Browser tab take effect on the broker immediately, without deploying the flow. They require the Node-RED permission stellio.write.

Input

Values from the message take precedence over the configuration.

Property	Type	Meaning
`msg.operation`	string	`list`, `get`, `setActive` or `delete`. Unknown values are treated as `list`.
`msg.apiUrl`	string	Overrides the API URL.
`msg.tenant`	string	Overrides the tenant.
`msg.contextUrl`	string	Overrides the context (Link header).
`msg.subscriptionId`	string	Overrides the Subscription ID (Get, Set Active, Delete).
`msg.active`	boolean or string `"true"`/`"false"`	Target state for `setActive`. If the property is missing, the Status selection from the dialog applies.
`msg.limit`	number	Overrides the limit for `list`.
`msg.payload`	any	Not evaluated; the message only acts as trigger.

Output

The message is extended with the broker response. For list, msg.payload contains for example:

[
  {
    "id": "urn:ngsi-ld:Subscription:7f3a2c1e-0000-4000-8000-000000000001",
    "type": "Subscription",
    "subscriptionName": "Subscription for entity type WeatherObserved.",
    "entities": [{"type": "WeatherObserved"}],
    "watchedAttributes": ["dateObserved"],
    "notificationTrigger": ["entityCreated", "attributeCreated", "attributeUpdated"],
    "isActive": true,
    "notification": {
      "format": "normalized",
      "endpoint": {"uri": "https://quantumleap.exampletown.example/v2/notify", "accept": "application/json"}
    },
    "@context": ["https://context.exampletown.example/main-context.jsonld"]
  }
]

Field	Meaning
`msg.payload`	`list`: array of subscription objects. `get`: one subscription object. `setActive`: broker response body; for an empty response (`204`) an object with `id` and `isActive`. `delete`: usually empty.
`msg.statusCode`	HTTP status code of the response.
`msg.headers`	Response headers of the broker.
`msg.count`	Result count from the `NGSILD-Results-Count` header for `list`, if the broker sends it.

Example flow

The package ships with a shared example flow for several Stellio nodes. You can import it in Node-RED via Menu → Import → Examples → @htag/node-red-contrib-hypertegrity-ngsi-ld → stellio-helper-nodes. The Stellio Subscriptions node is included in this shared example, but it is not wired as a complete Inject-Subscriptions-Debug flow; the following excerpt therefore shows a minimal wiring of this node. Alternatively, download stellio-helper-nodes.json and import it via Menu → Import.

Step 1

Inject

An Inject node triggers the query manually or at a fixed interval.

Step 2