OPC UA Server

OPC UA server starts and runs a custom OPC UA server on your infrastructure. Use it to construct a declarative information model out of folders, objects, and variables, and attach logic to process data reads and writes from external OPC UA clients.

This connector requires instance creation before you can configure network ports, map variable schemas, and manage the server lifecycle.

Variable interaction types

Variables are defined inside objects within the server's information model. Their operational behavior is governed by three distinct configuration categories:

• Getters (read-only for clients) – Managed internally by your logic. External OPC UA clients can read these values but cannot modify them. Update a getter variable by calling setValue whenever its real-world state changes.

• Setters (write-only for clients) – Designed to ingest data updates transmitted from external OPC UA clients. When a client modifies a setter node, the server triggers the onSet event handler. After your logic processes the data, you must invoke setValue to finalize the node synchronization.

• Requestors (read-on-demand for clients) – Variables whose data payloads are not held in continuous server cache memory. When a client reads a requestor node, the server fires the onRequest event handler. Your logic must then immediately calculate or fetch the data value and provide it to the server using setValue.

Server lifecycle

create

Creates an unconnected OPC UA server instance and maps out its information model structure.

Parameters

Input	Key	Description	Type
options	objects	An array defining folders, objects, and variables inside the server information model. Each node requires a path and a type (folder or object), along with getters, setters, or requestors type maps. An object can optionally define an integer offset to assign fixed numeric nodeIds to the object and its getter variables.	array
	port	The TCP port where the server listens for inbound connections. Separate parallel server instances must use distinct port numbers. Default 4840.	integer
	allowAnonymous	Controls whether external clients can connect without credentials. When false, clients must authenticate with the credentials of an integration user. Default true. See Protocol and encryption for the supported security level.	boolean

Output

Returns the name of the created instance.

Example

# options
port: 4841
allowAnonymous: true
objects:
  - path: Machine1
    type: folder
  - path: Machine1/Status
    type: object
    getters:
      currentSpeed: integer
      isHot: boolean
    setters:
      targetSpeed: integer
    requestors:
      uptime: string

start

Initializes and starts the underlying OPC UA server engine, exposing the endpoint to network traffic.

Parameters

None.

Output

Returns a string containing the primary endpoint connection URL (for example, opc.tcp://localhost:4841/UA/HeisenwareOPCUAServer), including when the server is already running. Throws an error if starting fails.

stop

Shuts down the active server engine and releases occupied network sockets.

Parameters

None.

Output

Returns nothing on a successful shutdown. Throws an error if stopping fails.

isStarted

Queries whether the underlying server engine is running and accepting client connections.

Parameters

None.

Output

Returns true if the server engine is active, or false if it is not.

delete

Removes the instance and its configuration.

Irreversible action

Deleting an instance removes its configuration. To run the server again, you must create a new instance.

Parameters

None.

Output

Returns true upon removal.

Data operations and events

setValue

Sets a new data value for a specific variable node on the server. This function updates getter nodes and serves as the response within your custom onSet and onRequest event scripts. The value must match the declared type, see Data type validation.

Parameters

Input	Description	Type
variablePath	The destination path targeting a specific node variable, formatted as path/to/object:variableName.	string
value	The data payload to store inside the node variable. Must match the declared schema data type.	any

Output

Returns true if the node variable updates successfully, or false if the path, variable, or data type is invalid (the reason logs as a warning).

Example

# variablePath
Machine1/Status:currentSpeed
# value
1500

onSet

Registers an event callback executed whenever an external OPC UA client writes a new value to a designated setter variable node.

Parameters

Input	Description	Type
variablePath	The path of the setter variable node to monitor, formatted as path/to/object:variableName.	string
listener	The callback evaluated when a write occurs. Receives the updated value sent by the client.	callback

Output

Returns 'subscribed' when successfully registered.

Example

# variablePath
Machine1/Status:targetSpeed
# listener
<callback>

onRequest

Registers an event callback executed whenever an external OPC UA client attempts to read a designated requestor variable node on-demand.

Parameters

Input	Description	Type
variablePath	The path of the requestor variable node to monitor, formatted as path/to/object:variableName.	string
listener	The callback evaluated when an on-demand read request arrives.	callback

Output

Returns 'subscribed' when successfully registered.

Example

# variablePath
Machine1/Status:uptime
# listener
<callback>

onServerUpdate

Registers a global diagnostic event callback executed whenever any variable node value updates on the server via setValue. Notifications are throttled, see Server update throttling.

Parameters

Input	Description	Type
listener	The callback executed on a value update. Receives an epoch millisecond timestamp and the modified variable path string.	callback

Output

Returns 'subscribed' when successfully registered.

Example

# listener
<callback>

Complete usage example

The steps show how to configure and run the server based on the model defined in the create example.

1

Create the server

Create the server instance with the desired information model, as shown in create.

2

Handle client writes (onSet)

When a client sets a new targetSpeed, process it and confirm the change by calling setValue.

# variablePath
Machine1/Status:targetSpeed
# listener
<callback>

3

Handle on-demand reads (onRequest)

When a client requests the uptime, calculate it inside the callback and provide it back via setValue.

# variablePath
Machine1/Status:uptime
# listener
<callback>

4

Update internal state (setValue)

A flow that reads the machine's actual speed periodically updates the currentSpeed getter.

# variablePath
Machine1/Status:currentSpeed
# value
1498

5

Start the server

After all handlers are configured, trigger start.

Tips and tricks

Server update throttling

The internal notification processor throttles onServerUpdate events to a maximum of once per second. Rapid successive setValue updates apply to memory values instantly, but listeners tracking global server updates receive notifications aggregated at one-second intervals.

Protocol and encryption

The local server operates with unencrypted communication profiles (SecurityPolicy.None and MessageSecurityMode.None). It does not support custom certificates or encrypted transport envelopes. Manage outer network security boundaries when routing client traffic across public infrastructure.

Data type validation

The underlying engine strictly validates values passed to setValue against the information model schema. Input data types must comply with these parameters:

Model data type	Expected platform primitive
boolean	Primitive JavaScript boolean values (true or false).
string, date	Textual strings. Dates must conform to standard ISO 8601 syntax.
integer, bigint, float, double, timestamp	Numeric values.
arrayBoolean, arrayInteger, arrayString, etc.	Standard arrays containing matching primitive types.