REST API Gen 2

5 min

The REST API connector lets Belden Horizon Data Operations make custom API calls to any external REST endpoint and publish the response back onto Message Broker.

Supported communication

Outbound (publish LE data to REST Server): Yes

Local topic subscription (trigger the outbound request from an LE topic): Yes

Response capture (publish the REST response to a local topic): Yes

Analytics IT Hub support: Yes

Authentication

None

Basic (username / password)

Bearer / Token

API Key (custom header)

OAuth2 Client Credentials with automatic refresh

Mutual TLS (client certificate / key)

Configurations

Field	Details	Required
Name	Name of the connector instance.	Yes
Endpoint / Base URL	Target REST endpoint, e.g. https://api.example.com	Yes
HTTP Method	HTTP verb used for every request: GET, POST, PUT, PATCH, or DELETE.	Yes
Authentication	Scheme used to authenticate to the endpoint. Selecting a mode reveals the credential fields it needs.	Yes
Username	Username for Basic authentication.	No
Password	Password for Basic authentication.	No
Token	Sent as Authorization: Bearer <token>.	No
API Key Header Name	Header name that carries the API key.	No
API Key Value	Secret value sent in the header named above.	No
OAuth2 - Token Endpoint	OAuth2 token endpoint URL.	No
OAuth2 - Client ID	OAuth2 client ID.	No
OAuth2 - Client Secret	Client secret credential paired with the Client ID.	No
OAuth2 - Scope	OAuth2 scope, comma separated.	No
CA Certificate (PEM)	Optional custom CA certificate (PEM) used to verify the server.	No
Client Certificate (PEM)	Client certificate for mutual TLS.	No
Client Key (PEM)	Client private key for mutual TLS.	No
Insecure skip verify	When enabled, the client does not verify the server's certificate chain or host name.	No
Headers	Custom HTTP headers sent with each request as key-value pairs. Example: Authorization: Bearer <token> or Content-Type: application/json.	No
Params	URL query string parameters.	No
Mapping	Request body / payload mapping.	No
Response Topic	NATS topic the response is published to.	No
Response Mode	body_only publishes correlationId, statusCode, and body; full_metadata also includes headers, latencyMs, and error.	No
Parallel Publish Count	Number of messages published in parallel. Higher values increase throughput and resource usage.	No
Request Timeout (s)	Per-request timeout in seconds.	No
Retry Count	Maximum number of retries on transport errors, 5xx, or 429.	No
Retry Backoff	Retry backoff strategy. Retry-After is honored on 429.	No
Connection Checking Interval (s)	How often, in seconds, the connector checks the REST endpoint for connectivity.	No
Throttling limit	Set a limit on the number of outbound messages per second. If sending data to a server that has restrictions on the rate of incoming messages, this ensures that no messages are lost.	No

Persistent storage configurations

Field	Details	Required
Persistent storage	If enabled, messages in the outbound queue are stored on disk. If there are interruptions in connection or power loss, messages are retained and eventually sent when the connection is restored.	No
Persistent storage size limit	Set the size limit for storing persisted data in GB.	No
Queue mode	Select the sequence of data transfer: FIFO or LIFO. Selecting FIFO (First In First Out) sends the earliest message first. Selecting LIFO (Last In First Out) sends the latest message first.	No

Response envelope

The response is published to the configured Response Topic. In body_only mode:

{
  "correlationId": "...",
  "statusCode": 200,
  "body": { ... }
}

In full_metadata mode:

{
  "correlationId": "...",
  "statusCode": 200,
  "headers": { "Content-Type": "application/json" },
  "latencyMs": 142,
  "body": { ... },
  "error": null
}

JSON response bodies are parsed and forwarded as objects. Non-JSON bodies are forwarded as strings. On error, the error field carries a structured, secret-free message.