Client¶

Canonical path: o6.client.Client

Root shortcut: o6.Client

Client ¶

Bases: _NativeClient

High-level OPC UA client.

with o6.Client("opc.tcp://localhost:4840") as client:
    print(client.read("ns=1;s=Temperature"))

Every request-issuing method returns a plain value when the client drives its own event loop, and an awaitable when it runs on an external one; see MaybeAwaitable. Operations on a client that is not connected raise instead of silently doing nothing.

See the Client guide for the whole picture, and the tutorials for task-by-task walkthroughs.

Attributes¶

config `instance-attribute` ¶

config

This client's ClientConfig.

root `instance-attribute` ¶

root = ObjectNode(
    _node_backend, "i=84", QualifiedName(0, "Root")
)

Node handle for the standard Root folder (i=84).

objects `instance-attribute` ¶

objects = ObjectNode(
    _node_backend, "i=85", QualifiedName(0, "Objects")
)

Node handle for the standard Objects folder (i=85).

types `instance-attribute` ¶

types = ObjectNode(
    _node_backend, "i=86", QualifiedName(0, "Types")
)

Node handle for the standard Types folder (i=86).

views `instance-attribute` ¶

views = ObjectNode(
    _node_backend, "i=87", QualifiedName(0, "Views")
)

Node handle for the standard Views folder (i=87).

T `class-attribute` `instance-attribute` ¶

T = TypeVar('T')

loop `property` ¶

loop

The asyncio event loop used by this client. Set at construction time, not modifiable afterwards.

state `property` ¶

state

Return (channel_state, session_state, connect_status).

connected `property` ¶

connected

Test if a client has both SecureChannel and Session connected.

onGlobalNotification `property` `writable` ¶

onGlobalNotification

Registry of handlers for every notification this client's underlying connection produces (lifecycle, service calls, ...).

Use as a decorator, a callable, or a list, exactly like the Server.on<category>Notification registries.

See Notification handler.

onLifecycleNotification `property` `writable` ¶

onLifecycleNotification

Registry of handlers for this client's own lifecycle notifications (connection started/stopped), independent of onGlobalNotification.

See Notification handler.

onServiceNotification `property` `writable` ¶

onServiceNotification

Registry of handlers for this client's own service-call begin/end notifications, independent of onGlobalNotification.

See Notification handler.

subscriptions `property` ¶

subscriptions

A copy of the active subscriptions for this client, keyed by id.

defaultSubscription `property` ¶

defaultSubscription

The clients' default subscription.

Raises RuntimeError when disconnected or when no default exists. With connect(createDefaultSubscription=False), create a subscription explicitly and pass it to monitor() or monitorEvent().

Functions¶

init ¶

__init__(
    endpointUrl="",
    loop=None,
    *,
    logger=None,
    certificate=None,
    privateKey=None,
    trustList=None,
    revocationList=None,
    securityMode=None,
    securityPolicy=None,
    applicationUri=None,
    username=None,
    password=None,
    allowNonePolicyPassword=False,
    name=""
)

Create a new OPC UA client.

The constructor accepts the most commonly needed settings as keyword arguments. Everything else — sessionName, requestedSessionTimeout, sessionLocaleIds, endpoint, and every other ClientConfig property — is set on client.config before calling connect():

client = o6.Client("opc.tcp://localhost:4840")
client.config.sessionName = "my-session"
client.config.requestedSessionTimeout = 60_000
client.config.sessionLocaleIds = ["en-US"]
client.config.endpoint = my_endpoint_description
client.config.setUsernamePassword("user", "secret")
client.connect()

Parameters:

Name	Type	Description	Default
`endpointUrl`	`str`	OPC UA endpoint to connect to, e.g. `"opc.tcp://localhost:4840"`. May also be passed later via `client.config.endpointUrl` and/or `connect()`.	`''`
`loop`	`AbstractEventLoop \| None`	Asyncio event loop to use. Defaults to the running loop, or a newly created one if none is running.	`None`
`logger`	`Logger \| None`	Python logger used for all client-level log output. Equivalent to `client.config.logger`.	`None`
`certificate`	`str \| Path \| bytes \| None`	Client certificate as a file path (`str` / `Path`) or raw bytes (DER/PEM). Equivalent to `client.config.certificate`.	`None`
`privateKey`	`str \| Path \| bytes \| None`	Private key matching certificate, as a file path or raw bytes. Equivalent to `client.config.privateKey`.	`None`
`trustList`	`list[str \| Path \| bytes] \| None`	Trusted server certificates, each as a file path or raw bytes. Equivalent to `client.config.trustList`.	`None`
`revocationList`	`list[str \| Path \| bytes] \| None`	Certificate revocation lists (CRL), each as a file path or raw bytes. Equivalent to `client.config.revocationList`.	`None`
`securityMode`	`int \| None`	OPC UA message security mode (`UA_MessageSecurityMode` integer or `o6.ns.ns0.datatypes.MessageSecurityMode` enum). Equivalent to `client.config.securityMode`.	`None`
`securityPolicy`	`str \| None`	URI or short name of the security policy, e.g. `"Basic256Sha256"`. Equivalent to `client.config.securityPolicy`.	`None`
`applicationUri`	`str \| None`	Application URI sent in the `ApplicationDescription`. Equivalent to `client.config.applicationUri`.	`None`
`username`	`str \| None`	Username for `UserNameIdentityToken` authentication. Equivalent to calling `client.config.setUsernamePassword(username, password)`.	`None`
`password`	`str \| None`	Password for `UserNameIdentityToken` authentication. Used together with username.	`None`
`allowNonePolicyPassword`	`bool`	Permit transmitting a username/password token without encryption. Defaults to False, including when credentials are supplied. Equivalent to `client.config.allowNonePolicyPassword`.	`False`
`name`	`str`	Optional client name. Must be a valid Python identifier, not match `server<digits>` or `::global`/`global`, and must be unique within the process. When omitted, an auto-generated `clientN` name is assigned.	`''`

del ¶

__del__()

connect ¶

connect(noSession=False, *, createDefaultSubscription=True)

Connect to the server.

Establishes a SecureChannel and, by default, a Session. Finalizes encryption settings (certificate / key) before connecting.

If noSession is True, only the SecureChannel is opened (useful for discovery or when a session will be activated manually later).

Creates the default subscription unless createDefaultSubscription=False. Opt out for sessions that only read, write, call, or browse, or supply an explicit subscription to monitoring methods. If post-session setup fails, including default-subscription creation, the session is closed before the error is raised.

Starts the background worker thread.

# sync
client.connect()

# async
await client.connect()

Parameters:

Name	Type	Description	Default
`noSession`	`bool`	Open only the SecureChannel, skip Session creation.	`False`
`createDefaultSubscription`	`bool`	Create the convenience subscription after connecting (default: `True`). Ignored when `noSession=True`.	`True`

disconnect ¶

disconnect(closeSession=True, deleteSubscriptions=True)

Disconnect from the server.

By default closes all subscriptions, ends the Session, and closes the SecureChannel, then stops the background worker thread.

Pass closeSession=False to close only the SecureChannel while keeping the Session alive (e.g. for session transfer). In that case deleteSubscriptions is ignored.

Safe to call when already disconnected or when the event loop is closed — returns None without raising.

# sync
client.disconnect()

# async
await client.disconnect()

Parameters:

Name	Type	Description	Default
`closeSession`	`bool`	Close the Session (and SecureChannel). When `False`, only the SecureChannel is closed.	`True`
`deleteSubscriptions`	`bool`	Delete all active subscriptions before disconnecting. Ignored when `closeSession` is `False`.	`True`

startReverseConnect ¶

startReverseConnect(port, hostnames=None)

Listen for an incoming OPC UA reverse connection from the server.

In the reverse-connect scenario the server initiates the TCP connection to the client. The client opens a listen socket on port and waits for the server to connect.

Close the connection with the standard disconnect.

client.startReverseConnect(port=4840, hostnames=["0.0.0.0"])
# ... use client ...
client.disconnect()

Parameters:

Name	Type	Description	Default
`port`	`int`	TCP port to listen on.	required
`hostnames`	`list[str] \| None`	Network interfaces to advertise. `None` or an empty list lets the stack decide (typically all interfaces).	`None`

activateCurrentSession ¶

activateCurrentSession()

Re-activate the session that is already associated with this client.

Sends an ActivateSession request using the client's stored identity token and credentials. Also creates the default subscription.

Typical use — session transfer, step 2 on the receiving client when the session was originally opened by this client and the SecureChannel has been renewed or re-established:

client.connect()                  # establishes session
# ... channel re-established ...
client.activateCurrentSession() # re-bind session to new channel

activateSession ¶

activateSession(authToken, serverNonce)

Activate a session that was created by another client.

Used for session transfer: client A's session is handed off to client B. Client B must first open a SecureChannel without a session (connect(noSession=True)), then call this method with the token and nonce obtained from the originating session.

# Client B — take over a session using credentials supplied
# by the originating session
client_b.connect(noSession=True)
client_b.activateSession(token, nonce)

Parameters:

Name	Type	Description	Default
`authToken`	`NodeId`	Authentication token (`NodeId`) from the originating session.	required
`serverNonce`	`bytes`	Server nonce bytes from the originating session.	required

enter ¶

__enter__()

Enter the sync context manager; connect if not already connected.

Calls connect when the client is not yet connected, then returns self. exit calls disconnect if the client is still connected when the block ends.

with Client("opc.tcp://localhost:4840") as client:
    value = client.read("ns=1;s=Temperature")

exit ¶

__exit__(exc_type, exc_value, traceback)

Exit the sync context manager; disconnect if still connected.

Calls disconnect when the client is still connected. Exceptions from the with block are not suppressed. See enter for full usage.

aenter `async` ¶

__aenter__()

Async counterpart of enter.

Same semantics — connects if not already connected and returns self — but uses await internally. aexit awaits disconnect.

async with Client("opc.tcp://localhost:4840") as client:
    value = await client.read("ns=1;s=Temperature")

aexit `async` ¶

__aexit__(exc_type, exc_value, traceback)

Exit the async context manager; disconnect if still connected.

Awaits disconnect when the client is still connected. Exceptions from the async with block are not suppressed. See aenter for full usage.

getitem ¶

__getitem__(key)

Resolve a node ID to a typed Node object.

Reads NodeClass and BrowseName from the server and returns the matching Node subclass (e.g. VariableNode, ObjectNode, …). Service and attribute failures raise StatusCodeError; an unknown ID has code BAD_NODE_ID_UNKNOWN. Malformed responses raise RuntimeError.

key accepts anything that can be converted to a NodeId: a string ("ns=1;s=Temperature"), an integer (numeric node id in namespace 0), or a NodeId instance.

node = client["ns=1;s=Temperature"]        # sync
node = await client["ns=1;s=Temperature"]  # async

serviceFindServers ¶

serviceFindServers(request)

Raw FindServers service call — discover servers known to a discovery server.

OPC UA Part 4 §5.5.2

serviceFindServersOnNetwork ¶

serviceFindServersOnNetwork(request)

Raw FindServersOnNetwork service call — enumerate servers registered via mDNS/LDS.

OPC UA Part 4 §5.5.3

serviceGetEndpoints ¶

serviceGetEndpoints(request)

Raw GetEndpoints service call — retrieve the endpoint descriptions of a server.

OPC UA Part 4 §5.5.4

invalidateNodeCache ¶

invalidateNodeCache(target=None)

Invalidate cached child navigation for this client's existing handles.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike \| None`	Invalidate every handle for this node, or all handles when omitted. The next navigation browses again. Async callers must await this operation.	`None`

Use this after external address-space changes or raw service browsing. Complete browse() calls invalidate their target automatically, and client node/reference mutations and namespace refresh invalidate all handles. Cached misses are browsed again once before raising.

serviceAddNodes ¶

serviceAddNodes(request)

Raw AddNodes service call — add one or more nodes to the address space.

OPC UA Part 4 §5.8.2

serviceDeleteNodes ¶

serviceDeleteNodes(request)

Raw DeleteNodes service call — remove one or more nodes from the address space.

OPC UA Part 4 §5.8.4

serviceAddReferences ¶

serviceAddReferences(request)

Raw AddReferences service call — add references between nodes.

OPC UA Part 4 §5.8.3

serviceDeleteReferences ¶

serviceDeleteReferences(request)

Raw DeleteReferences service call — remove references between nodes.

OPC UA Part 4 §5.8.5

serviceBrowse ¶

serviceBrowse(request)

Raw Browse service call — navigate the address space from one or more start nodes.

Returns references according to the BrowseDescription filter in the request. Use serviceBrowseNext to continue if the response indicates more results are available.

OPC UA Part 4 §5.9.2

serviceBrowseNext ¶

serviceBrowseNext(request)

Raw BrowseNext service call — continue a Browse that returned a continuation point.

OPC UA Part 4 §5.9.3

serviceTranslateBrowsePathsToNodeIds ¶

serviceTranslateBrowsePathsToNodeIds(request)

Raw TranslateBrowsePathsToNodeIds service call — resolve browse paths to NodeIds.

OPC UA Part 4 §5.9.4

serviceRegisterNodes ¶

serviceRegisterNodes(request)

Raw RegisterNodes service call — obtain optimised NodeIds for repeated access.

OPC UA Part 4 §5.9.5

serviceUnregisterNodes ¶

serviceUnregisterNodes(request)

Raw UnregisterNodes service call — release NodeIds obtained via RegisterNodes.

OPC UA Part 4 §5.9.6

serviceRead ¶

serviceRead(request)

Raw Read service call — read one or more node attributes.

OPC UA Part 4 §5.11.2

serviceHistoryRead ¶

serviceHistoryRead(request)

Raw HistoryRead service call — read historical values or events from nodes.

OPC UA Part 4 §5.11.3

serviceWrite ¶

serviceWrite(request)

Raw Write service call — write one or more node attribute values.

OPC UA Part 4 §5.11.4

serviceHistoryUpdate ¶

serviceHistoryUpdate(request)

Raw HistoryUpdate service call — insert, replace, or delete historical data.

OPC UA Part 4 §5.11.5

serviceCall ¶

serviceCall(request)

Raw Call service call — invoke one or more OPC UA methods.

OPC UA Part 4 §5.12.2

getRemoteDataTypes ¶

getRemoteDataTypes(typeNodes=None)

Read custom StructureDefinition data types from the server.

Browses the server's DataType hierarchy (rooted at Structure, NodeId i=22) and reads the DataTypeDefinition and BrowseName attributes for every discovered node. Only nodes that carry a StructureDefinition (structs, structs-with-optional-fields, and unions) are included in the result.

Pass typeNodes to restrict the query to a specific set of DataType NodeIds instead of walking the full hierarchy. Passing an empty list returns [] immediately without contacting the server. Expanded references with a namespace URI or remote server index are skipped; only local NodeIds can be read through this session.

Each entry in the returned list is a dict with the following keys:

typeName (str) — BrowseName.name of the DataType node.
typeId (NodeId) — NodeId of the DataType node.
binaryEncodingId (NodeId) — default binary encoding NodeId (StructureDefinition.defaultEncodingId).
structureType ([StructureType][o6.ns.ns0.datatypes.StructureType]) — the information-model structure category.
membersSize (int) — number of fields in the structure.

Parameters:

Name	Type	Description	Default
`typeNodes`	`list[NodeIdLike] \| None`	Explicit DataType NodeIds to query. `None` (default) walks the full `Structure` subtype hierarchy.	`None`

updateRemoteNamespaces ¶

updateRemoteNamespaces()

Atomically synchronize namespace mappings and custom datatypes.

The client first installs a provisional wire-index mapping when a URI has several compiled versions, reads the server's NamespaceMetadata, then selects an exact version or the latest available fallback. The final Python mapping, SecureChannel decoder mapping, and custom datatype chain are replaced as one snapshot. A failed refresh leaves the preceding snapshot usable. Call this again if a connected server adds namespaces at runtime; unchanged snapshots are not rebuilt.

getEndpoints ¶

getEndpoints(
    endpointUrl, *, localeIds=None, profileUris=None
)

Return the endpoints advertised by a server.

Sends a GetEndpoints request to endpointUrl. No active session is required — connect with connect(noSession=True) first if the client is not yet connected.

Each [EndpointDescription][o6.ns.ns0.datatypes.EndpointDescription] in the result describes one available endpoint and includes the endpoint URL, security mode, security policy URI, transport profile URI, server certificate, and the list of supported [UserTokenPolicy][o6.ns.ns0.datatypes.UserTokenPolicy] entries.

client.connect(noSession=True)
endpoints = client.getEndpoints("opc.tcp://localhost:4840")
for ep in endpoints:
    print(ep.endpointUrl, ep.securityMode, ep.securityPolicyUri)

Parameters:

Name	Type	Description	Default
`endpointUrl`	`str`	URL of the server to query, e.g. `"opc.tcp://localhost:4840"`.	required
`localeIds`	`list[str] \| None`	Preferred locales for localised strings in the response (e.g. `["en-US", "de-DE"]`). `None` returns the server's default locale.	`None`
`profileUris`	`list[str] \| None`	Restrict the result to endpoints that match one of these transport profile URIs. `None` returns all endpoints.	`None`

Raises:

Type	Description
`StatusCodeError`	The discovery service failed or is unsupported.

findServers ¶

findServers(
    endpointUrl, *, serverUris=None, localeIds=None
)

Return servers registered at a discovery server or known to a server.

Sends a FindServers request to endpointUrl. Typically called against a Local Discovery Server (LDS) at "opc.tcp://localhost:4840" to enumerate all servers registered on the host, or against any server to retrieve its own [ApplicationDescription][o6.ns.ns0.datatypes.ApplicationDescription].

No active session is required — connect(noSession=True) is sufficient.

Each [ApplicationDescription][o6.ns.ns0.datatypes.ApplicationDescription] in the result contains the application name, application URI, application type, product URI, and a list of discovery URLs that can be passed to getEndpoints.

client.connect(noSession=True)
servers = client.findServers("opc.tcp://localhost:4840")
for srv in servers:
    print(srv.applicationUri, srv.discovery_urls)

Parameters:

Name	Type	Description	Default
`endpointUrl`	`str`	URL of the discovery server or server to query.	required
`localeIds`	`list[str] \| None`	Preferred locales for the `ApplicationDescription.application_name` field. `None` uses the server's default locale.	`None`
`serverUris`	`list[str] \| None`	Restrict the result to servers whose `applicationUri` matches one of these strings. `None` returns all known servers.	`None`

Raises:

Type	Description
`StatusCodeError`	The discovery service failed or is unsupported.

findServersOnNetwork ¶

findServersOnNetwork(
    startingRecordId=0,
    maxRecordsToReturn=0,
    serverCapabilityFilter=None,
)

Return servers visible on the network via a Local Discovery Server (LDS).

Sends a FindServersOnNetwork request to the connected LDS. The LDS maintains a registry of servers that have announced themselves via mDNS or the RegisterServer2 service. This call is only meaningful when connected to an LDS; a regular OPC UA server will return an empty list or an error.

The result is paginated: use startingRecordId and maxRecordsToReturn to page through large registries. The record_id field on each [ServerOnNetwork][o6.ns.ns0.datatypes.ServerOnNetwork] entry can be used as the startingRecordId for the next page.

Each [ServerOnNetwork][o6.ns.ns0.datatypes.ServerOnNetwork] entry contains the server name, discovery URL, and a list of capability strings (e.g. "DA" for Data Access, "HE" for Historical Events).

# Fetch the first 100 servers that support Data Access
servers = client.findServersOnNetwork(
    maxRecordsToReturn=100,
    serverCapabilityFilter=["DA"],
)

Parameters:

Name	Type	Description	Default
`startingRecordId`	`int`	Record ID to start from for pagination. `0` starts from the beginning of the registry.	`0`
`maxRecordsToReturn`	`int`	Maximum number of entries to return. `0` lets the server decide (typically returns all entries).	`0`
`serverCapabilityFilter`	`list[str] \| None`	Restrict the result to servers that advertise all of the given capability strings. `None` returns servers regardless of capabilities.	`None`

Raises:

Type	Description
`StatusCodeError`	The discovery service failed or is unsupported.

read ¶

read(
    target,
    *,
    attr=o6.AttributeId.VALUE,
    timestampsToReturn=None,
    valueOnly=True,
    range=None
)

Read one attribute from a node or a list of nodes.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike \| list[NodeIdLike]`	One NodeId-like target (including a Node) or a list of targets.	required
`attr`	`AttributeId \| str`	AttributeId or case-insensitive attribute name; keyword-only.	`VALUE`
`timestampsToReturn`	`TimestampsToReturn \| None`	SOURCE (the default), SERVER, BOTH, or NEITHER.	`None`
`valueOnly`	`bool`	Return values for all Good-severity statuses when True, discarding status and timestamps. False returns DataValues for the caller to interpret, including Uncertain and Bad statuses.	`True`
`range`	`IndexRange \| list[IndexRange]`	Inclusive OPC UA range string, stop-exclusive slice or tuple of slices, or one range per target. A scalar range broadcasts. None or an empty string reads the entire attribute.	`None`

Returns:

Type	Description
`MaybeAwaitable[Any]`	A scalar for one target, or a list in input order. An empty target
`MaybeAwaitable[Any]`	list returns []. Raw DataValues retain per-target statuses and
`MaybeAwaitable[Any]`	supported timestamp metadata, including failed reads.

Raises:

Type	Description
`StatusCodeError`	A service failure or an Uncertain/Bad value-only status. The code property preserves the status; batch errors include the failed index in an exception note. Nonempty ranges on non-Value attributes return BAD_INDEX_RANGE_NO_DATA.
`TypeError`	An argument has an unsupported Python type.
`ValueError`	An attribute name, slice, or range-list length is invalid.

write ¶

write(
    target,
    value=_WRITE_UNSET,
    *,
    attr=o6.AttributeId.VALUE,
    range=None
)

Write one attribute using a scalar, parallel lists, or a mapping.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike \| list[NodeIdLike] \| Mapping[NodeIdLike, Any]`	One NodeId-like target (including a Node), a list of targets, or a target-to-value mapping.	required
`value`	`Any`	Value for one target, or an equal-length list for target lists. Omit for mappings. A list for a scalar target is an array value. Explicit None writes a null value where the target permits it; omitting a scalar value raises ValueError. DataValues retain supported status and timestamp metadata. Non-Value attributes require their expected datatype and reject status/timestamp metadata with BAD_WRITE_NOT_SUPPORTED.	`_WRITE_UNSET`
`attr`	`AttributeId \| str`	AttributeId or case-insensitive attribute name; keyword-only.	`VALUE`
`range`	`IndexRange \| list[IndexRange]`	Inclusive OPC UA range string, stop-exclusive slice or tuple of slices, or one range per target. A scalar range broadcasts. None or an empty string writes the entire attribute. Nonempty ranges require Value; mappings do not accept ranges.	`None`

Returns:

Type	Description
`MaybeAwaitable[StatusCode \| list[StatusCode]]`	One StatusCode for a scalar target, otherwise a list in input order,
`MaybeAwaitable[StatusCode \| list[StatusCode]]`	including one-element batches. Empty lists/mappings return []. Every
`MaybeAwaitable[StatusCode \| list[StatusCode]]`	target is attempted despite per-target status failures; check results.

Raises:

Type	Description
`StatusCodeError`	A service-level failure; code preserves its status.
`TypeError`	An argument has an unsupported Python type.
`ValueError`	Input shapes, attribute names, or ranges are invalid. Shapes and ranges are validated before any writes.

call ¶

call(objectId, methodId, inputArgs=[])

Invoke a method on a node.

Parameters:

Name	Type	Description	Default
`objectId`	`NodeIdLike`	The object node id that owns the method.	required
`methodId`	`NodeIdLike`	The method node id to invoke.	required
`inputArgs`	`list[Any]`	Positional input arguments to pass to the method.	`[]`

Returns:

Type	Description
`MaybeAwaitable[tuple[StatusCode, *(tuple[Any, ...])]]`	`(statusCode, output1, output2, ...)`, including bad method statuses
`MaybeAwaitable[tuple[StatusCode, *(tuple[Any, ...])]]`	and any available outputs. Invalid method selection and argument
`MaybeAwaitable[tuple[StatusCode, *(tuple[Any, ...])]]`	validation also produce method results. A zero-output result is
`MaybeAwaitable[tuple[StatusCode, *(tuple[Any, ...])]]`	`(statusCode,)`.

Raises:

Type	Description
`StatusCodeError`	The Call service failed; `code` retains the original status. Method-result failures do not raise.
`TypeError`	An argument cannot be converted to an OPC UA value.

browse ¶

browse(
    target,
    *,
    direction=ns0.datatypes.BrowseDirection.FORWARD,
    reftype=ns0.reftypes.HierarchicalReferences,
    refsubtypes=True,
    nodeClassMask=ns0.datatypes.NodeClass.UNSPECIFIED,
    resultMask=ns0.datatypes.BrowseResultMask.ALL
)

Browse references from a node.

The method transparently follows server-issued continuation points by calling BrowseNext until all references have been collected, so the returned list is always complete even when the server splits the response into multiple batches.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike`	The node id to browse from.	required
`direction`	`BrowseDirection`	The browse direction (forward, inverse, or both).	`FORWARD`
`reftype`	`NodeIdLike`	A reference type to filter by, or `None` for all types.	`HierarchicalReferences`
`refsubtypes`	`bool`	If `True`, include subtypes of the reference type.	`True`
`nodeClassMask`	`int`	A node-class mask to filter the target nodes, as the `UInt32` the service takes. Compose the `NodeClass` members you want with `\|`.	`UNSPECIFIED`
`resultMask`	`int`	A browse result mask to customize returned fields, as the `UInt32` the service takes. Compose the `BrowseResultMask` members you want with `\|`. Defaults to `ALL`; `NONE` returns only target NodeIds.	`ALL`

Returns:

Type	Description
`MaybeAwaitable[list[ReferenceDescription]]`	A list of `ReferenceDescription` objects describing the found
`MaybeAwaitable[list[ReferenceDescription]]`	references. Sync callers receive the list directly; async tasks
`MaybeAwaitable[list[ReferenceDescription]]`	must await the call. Node and NodeId targets have the same contract.

Raises:

Type	Description
`StatusCodeError`	Browse or BrowseNext returned a service or result failure. Outstanding continuation points are released on failure or cancellation where the connection permits release.

browsePage ¶

browsePage(
    target,
    *,
    maxReferences=0,
    direction=ns0.datatypes.BrowseDirection.FORWARD,
    reftype=ns0.reftypes.HierarchicalReferences,
    refsubtypes=True,
    nodeClassMask=ns0.datatypes.NodeClass.UNSPECIFIED,
    resultMask=ns0.datatypes.BrowseResultMask.ALL
)

Fetch one page of references, matching Server.browsePage.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike`	Node to browse from.	required
`maxReferences`	`int`	Requested page size; zero means no client-side cap.	`0`
`direction`	`BrowseDirection`	Forward, inverse, or both reference directions.	`FORWARD`
`reftype`	`NodeIdLike`	ReferenceType to follow; defaults to HierarchicalReferences.	`HierarchicalReferences`
`refsubtypes`	`bool`	Include subtypes of the reference type.	`True`
`nodeClassMask`	`int`	Restrict target node classes; zero means all classes.	`UNSPECIFIED`
`resultMask`	`int`	Reference fields to return; defaults to `ALL`. Zero returns target IDs only.	`ALL`

Returns:

Type	Description
`MaybeAwaitable[BrowseResult]`	One BrowseResult, directly for sync callers or awaitable in async
`MaybeAwaitable[BrowseResult]`	code. Continue with `browseNext(False, token)`, or release an unused
`MaybeAwaitable[BrowseResult]`	token with `browseNext(True, token)`. Tokens belong to this session.

Raises:

Type	Description
`StatusCodeError`	The service or individual browse failed.

browseNext ¶

browseNext(releaseContinuationPoint, continuationPoint)

Continue or release pages from browsePage.

Parameters:

Name	Type	Description	Default
`releaseContinuationPoint`	`bool`	Release tokens instead of fetching pages.	required
`continuationPoint`	`bytes \| list[bytes] \| tuple[bytes, ...]`	One token or a list/tuple of session-owned tokens.	required

Returns:

Type	Description
`MaybeAwaitable[list[BrowseResult]]`	One BrowseResult per token, always as a list. An empty input returns
`MaybeAwaitable[list[BrowseResult]]`	an empty list. Await the operation in async code.

Raises:

Type	Description
`StatusCodeError`	The service or any continuation operation failed.

translateBrowsePathsToNodeIds ¶

translateBrowsePathsToNodeIds(
    browsePath: list[BrowsePath],
) -> MaybeAwaitable[list[ns0.datatypes.BrowsePathResult]]

translateBrowsePathsToNodeIds(
    browsePath: BrowsePath,
) -> MaybeAwaitable[ns0.datatypes.BrowsePathResult]

translateBrowsePathsToNodeIds(browsePath)

Resolve one BrowsePath or a list of paths.

Parameters:

Name	Type	Description	Default
`browsePath`	`BrowsePath \| list[BrowsePath]`	A BrowsePath or list of BrowsePaths to resolve.	required

Returns:

Type	Description
`MaybeAwaitable[BrowsePathResult \| list[BrowsePathResult]]`	One BrowsePathResult for a scalar input, or a list in input order.
`MaybeAwaitable[BrowsePathResult \| list[BrowsePathResult]]`	Each result retains its status, including partial/unresolved paths;
`MaybeAwaitable[BrowsePathResult \| list[BrowsePathResult]]`	an empty list returns an empty list. Await in async code.

Raises:

Type	Description
`StatusCodeError`	The service failed. Use `serviceTranslateBrowsePathsToNodeIds` for raw requests/responses.

browseSimplifiedBrowsePaths ¶

browseSimplifiedBrowsePaths(origin, browsePath)

Resolve a BrowseName chain through forward hierarchical references.

Parameters:

Name	Type	Description	Default
`origin`	`NodeIdLike`	Node at which the path starts.	required
`browsePath`	`QualifiedName \| str \| list[QualifiedName \| str] \| tuple[QualifiedName \| str, ...]`	One QualifiedName/string or a list/tuple forming one path.	required

Returns:

Type	Description
`MaybeAwaitable[BrowsePathResult]`	One BrowsePathResult, retaining unresolved-path status. Await in
`MaybeAwaitable[BrowsePathResult]`	async code. Unlike `browseRecursive`, this follows a specified path.

browseInteractive ¶

browseInteractive(nodeId=None)

Open a curses-based interactive browser for the address space.

Requires the curses module (install windows-curses on Windows). Returns the selected NodeId string (or BrowsePath string) when the user quits with n / p; returns None otherwise.

Parameters:

Name	Type	Description	Default
`nodeId`	`NodeIdLike \| None`	Optional starting node id (defaults to `Objects`).	`None`

historyRead ¶

historyRead(
    target,
    startTime,
    endTime,
    numValuesPerNode=0,
    returnBounds=False,
    timestampsToReturn=ns0.datatypes.TimestampsToReturn.BOTH,
)

Read raw historical values for one or more nodes.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike \| list[NodeIdLike]`	A node id or list of node ids to read history from.	required
`startTime`	`datetime`	The start time for the history interval.	required
`endTime`	`datetime`	The end time for the history interval.	required
`numValuesPerNode`	`int`	Maximum number of values to return per node.	`0`
`returnBounds`	`bool`	If `True`, include boundary values at the interval edges.	`False`
`timestampsToReturn`	`TimestampsToReturn`	Which timestamps to return with each value.	`BOTH`

Returns:

Type	Description
`Any`	Historical data for the requested nodes. Server-issued continuation
`Any`	points are followed until the interval or per-node limit is exhausted.

historyUpdateInsert ¶

historyUpdateInsert(target, values)

Insert new historical values into a node's history.

Insertion fails for any timestamp that already has a value stored. Use historyUpdateReplace to overwrite existing entries.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike`	The node id whose history is being updated.	required
`values`	`list[DataValue]`	The historical values to insert.	required

Returns:

Type	Description
`Any`	The raw result of the history update operation.

historyUpdateReplace ¶

historyUpdateReplace(target, values)

Replace existing historical values for a node.

Replacement requires that a value already exists at each provided timestamp. Use historyUpdateInsert to add new entries.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike`	The node id whose history is being updated.	required
`values`	`list[DataValue]`	The historical values to replace existing entries with.	required

Returns:

Type	Description
`Any`	The raw result of the history update operation.

historyUpdateDelete ¶

historyUpdateDelete(target, startTime, endTime)

Delete historical values from a node.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike`	The node id whose history should be deleted.	required
`startTime`	`datetime`	The start of the deletion interval.	required
`endTime`	`datetime`	The end of the deletion interval.	required

Returns:

Type	Description
`Any`	The raw result of the history delete operation.

addObject ¶

addObject(
    name,
    parent,
    *,
    nodeId=None,
    typeDefinition=ns0.objtypes.BaseObjectType,
    ns=1,
    parentReference=ns0.reftypes.Organizes
)

Create an Object and return a usable handle, matching Server.addObject.

Parameters:

Name	Type	Description	Default
`name`	`LocalizedTextLike`	BrowseName and DisplayName of the Object.	required
`parent`	`NodeIdLike`	Parent node.	required
`nodeId`	`NodeIdLike \| None`	Requested NodeId; the server assigns one when omitted.	`None`
`typeDefinition`	`NodeIdLike`	ObjectType, defaulting to BaseObjectType.	`BaseObjectType`
`ns`	`int`	Namespace index for the BrowseName.	`1`
`parentReference`	`NodeIdLike`	Parent reference, defaulting to Organizes.	`Organizes`

Returns:

Type	Description
`MaybeAwaitable[ObjectNode]`	An ObjectNode, directly in sync code or awaitable in async code.
`MaybeAwaitable[ObjectNode]`	`addObjectNode` remains the attribute-based API returning a NodeId.

Raises:

Type	Description
`StatusCodeError`	Remote node creation failed.

addVariable ¶

addVariable(
    name,
    parent,
    value=None,
    *,
    nodeId=None,
    dataType=None,
    typeDefinition=ns0.vartypes.BaseDataVariableType,
    writable=True,
    ns=1,
    parentReference=ns0.reftypes.Organizes
)

Create a Variable with friendly inputs, matching Server.addVariable.

Parameters:

Name	Type	Description	Default
`name`	`LocalizedTextLike`	BrowseName and DisplayName of the Variable.	required
`parent`	`NodeIdLike`	Parent node.	required
`value`	`Any`	Initial value; its datatype and array rank are inferred. Typed empty NumPy arrays preserve their datatype and rank; empty Python sequences require an explicit dataType.	`None`
`nodeId`	`NodeIdLike \| None`	Requested NodeId; assigned by the server when omitted.	`None`
`dataType`	`NodeIdLike \| None`	Explicit OPC UA datatype, otherwise inferred from value.	`None`
`typeDefinition`	`NodeIdLike`	VariableType, defaulting to BaseDataVariableType.	`BaseDataVariableType`
`writable`	`bool`	Allow client writes; defaults to True.	`True`
`ns`	`int`	Namespace index for the BrowseName.	`1`
`parentReference`	`NodeIdLike`	Parent reference, defaulting to Organizes.	`Organizes`

Returns:

Type	Description
`MaybeAwaitable[VariableNode]`	A VariableNode, directly in sync code or awaitable in async code.
`MaybeAwaitable[VariableNode]`	`addVariableNode` retains attribute-based creation and NodeId results.
`MaybeAwaitable[VariableNode]`	History registration and Python behavior installation are server-only.

Raises:

Type	Description
`StatusCodeError`	Remote node creation failed.
`TypeError`	The initial value has no inferable datatype.

addVariableNode ¶

addVariableNode(
    *,
    parent,
    parentReference=ns0.reftypes.HasComponent,
    browseName,
    requestedNodeId=None,
    attributes,
    typeDefinition=ns0.vartypes.BaseDataVariableType
)

Add a variable node to the server.

Parameters:

Name	Type	Description	Default
`parent`	`NodeIdLike`	The parent node id for the variable.	required
`browseName`	`QualifiedName \| str`	The BrowseName for the variable.	required
`attributes`	`VariableAttributes`	The variable attributes.	required
`requestedNodeId`	`NodeIdLike \| None`	Optionally request a specific node id.	`None`
`parentReference`	`NodeIdLike`	The reference type used to link the variable.	`HasComponent`
`typeDefinition`	`NodeIdLike`	The variable type definition node id.	`BaseDataVariableType`

Returns:

Type	Description
`MaybeAwaitable[NodeId]`	The newly created variable node id.

addVariableTypeNode ¶

addVariableTypeNode(
    *,
    parent,
    parentReference=ns0.reftypes.HasSubtype,
    browseName,
    requestedNodeId=None,
    attributes
)

Add a variable type node to the server.

Parameters:

Name	Type	Description	Default
`parent`	`NodeIdLike`	The parent node id for the type node.	required
`browseName`	`QualifiedName \| str`	The BrowseName for the variable type.	required
`attributes`	`VariableTypeAttributes`	The variable type attributes.	required
`requestedNodeId`	`NodeIdLike \| None`	Optionally request a specific node id.	`None`
`parentReference`	`NodeIdLike`	The reference type used to link the type node.	`HasSubtype`

Returns:

Type	Description
`MaybeAwaitable[NodeId]`	The newly created variable type node id.

addObjectNode ¶

addObjectNode(
    *,
    parent,
    parentReference=ns0.reftypes.HasComponent,
    browseName,
    requestedNodeId=None,
    attributes,
    typeDefinition=ns0.objtypes.BaseObjectType
)

Add an object node to the server.

Parameters:

Name	Type	Description	Default
`parent`	`NodeIdLike`	The parent node id for the object.	required
`browseName`	`QualifiedName \| str`	The BrowseName for the object.	required
`attributes`	`ObjectAttributes`	The object attributes.	required
`requestedNodeId`	`NodeIdLike \| None`	Optionally request a specific node id.	`None`
`parentReference`	`NodeIdLike`	The reference type used to link the object.	`HasComponent`
`typeDefinition`	`NodeIdLike`	The object type definition node id.	`BaseObjectType`

Returns:

Type	Description
`MaybeAwaitable[NodeId]`	The newly created object node id.

addObjectTypeNode ¶

addObjectTypeNode(
    *,
    parent,
    parentReference=ns0.reftypes.HasSubtype,
    browseName,
    requestedNodeId=None,
    attributes
)

Add an object type node to the server.

Parameters:

Name	Type	Description	Default
`parent`	`NodeIdLike`	The parent node id for the type.	required
`browseName`	`QualifiedName \| str`	The BrowseName for the object type.	required
`attributes`	`ObjectTypeAttributes`	The object type attributes.	required
`requestedNodeId`	`NodeIdLike \| None`	Optionally request a specific node id.	`None`
`parentReference`	`NodeIdLike`	The reference type used to link the type node.	`HasSubtype`

Returns:

Type	Description
`MaybeAwaitable[NodeId]`	The newly created object type node id.

addViewNode ¶

addViewNode(
    *,
    parent,
    parentReference=ns0.reftypes.HasComponent,
    browseName,
    requestedNodeId=None,
    attributes
)

Add a view node to the server.

Parameters:

Name	Type	Description	Default
`parent`	`NodeIdLike`	The parent node id for the view.	required
`browseName`	`QualifiedName \| str`	The BrowseName for the view.	required
`attributes`	`ViewAttributes`	The view attributes.	required
`requestedNodeId`	`NodeIdLike \| None`	Optionally request a specific node id.	`None`
`parentReference`	`NodeIdLike`	The reference type used to link the view.	`HasComponent`

Returns:

Type	Description
`MaybeAwaitable[NodeId]`	The newly created view node id.

addReferenceTypeNode ¶

addReferenceTypeNode(
    *,
    parent,
    parentReference=ns0.reftypes.HasSubtype,
    browseName,
    requestedNodeId=None,
    attributes
)

Add a reference type node to the server.

Parameters:

Name	Type	Description	Default
`parent`	`NodeIdLike`	The parent node id for the reference type.	required
`browseName`	`QualifiedName \| str`	The BrowseName for the reference type.	required
`attributes`	`ReferenceTypeAttributes`	The reference type attributes.	required
`requestedNodeId`	`NodeIdLike \| None`	Optionally request a specific node id.	`None`
`parentReference`	`NodeIdLike`	The reference type used to link the node.	`HasSubtype`

Returns:

Type	Description
`MaybeAwaitable[NodeId]`	The newly created reference type node id.

addDataTypeNode ¶

addDataTypeNode(
    *,
    parent,
    parentReference=ns0.reftypes.HasSubtype,
    browseName,
    requestedNodeId=None,
    attributes
)

Add a data type node to the server.

Parameters:

Name	Type	Description	Default
`parent`	`NodeIdLike`	The parent node id for the data type.	required
`browseName`	`QualifiedName \| str`	The BrowseName for the data type.	required
`attributes`	`DataTypeAttributes`	The data type attributes.	required
`requestedNodeId`	`NodeIdLike \| None`	Optionally request a specific node id.	`None`
`parentReference`	`NodeIdLike`	The reference type used to link the node.	`HasSubtype`

Returns:

Type	Description
`MaybeAwaitable[NodeId]`	The newly created data type node id.

addMethodNode ¶

addMethodNode(
    *,
    parent,
    parentReference=ns0.reftypes.HasComponent,
    browseName,
    requestedNodeId=None,
    attributes
)

Add a method node to the server.

Parameters:

Name	Type	Description	Default
`parent`	`NodeIdLike`	The parent node id for the method.	required
`browseName`	`QualifiedName \| str`	The BrowseName for the method.	required
`attributes`	`MethodAttributes`	The method attributes.	required
`requestedNodeId`	`NodeIdLike \| None`	Optionally request a specific node id.	`None`
`parentReference`	`NodeIdLike`	The reference type used to link the method.	`HasComponent`

Returns:

Type	Description
`MaybeAwaitable[NodeId]`	The newly created method node id.

deleteNode ¶

deleteNode(
    nodeId: list[NodeIdLike],
    deleteTargetReferences: bool = True,
) -> MaybeAwaitable[list[o6.StatusCode]]

deleteNode(
    nodeId: NodeIdLike, deleteTargetReferences: bool = True
) -> MaybeAwaitable[o6.StatusCode]

deleteNode(nodeId, deleteTargetReferences=True)

Delete one or more nodes using the remote session permissions.

Parameters:

Name	Type	Description	Default
`nodeId`	`NodeIdLike \| list[NodeIdLike]`	A node, node id, or list of these targets.	required
`deleteTargetReferences`	`bool`	If True (default), remove incoming references from remaining nodes. False leaves dangling references.	`True`

Returns:

Type	Description
`MaybeAwaitable[StatusCode \| list[StatusCode]]`	One StatusCode for a scalar target, otherwise a list in input order,
`MaybeAwaitable[StatusCode \| list[StatusCode]]`	including one-element batches. All targets are attempted despite
`MaybeAwaitable[StatusCode \| list[StatusCode]]`	per-target failures. An empty list returns [] without a request.
`MaybeAwaitable[StatusCode \| list[StatusCode]]`	Async callers must await the result.

Raises:

Type	Description
`StatusCodeError`	The service failed.
`TypeError`	An argument has an invalid Python type.
`ValueError`	A target cannot be converted to a node id.

addReference ¶

addReference(
    source,
    reftype,
    target,
    forward=True,
    targetNodeClass=ns0.datatypes.NodeClass.UNSPECIFIED,
    targetServerUri="",
)

Add a reference between two nodes.

Parameters:

Name	Type	Description	Default
`source`	`NodeIdLike`	The source node id for the reference.	required
`reftype`	`NodeIdLike`	The reference type id.	required
`target`	`NodeIdLike \| ExpandedNodeId`	The target node id.	required
`forward`	`bool`	If `True`, create a forward reference.	`True`
`targetNodeClass`	`NodeClass`	Optional target node class for the reference.	`UNSPECIFIED`
`targetServerUri`	`str`	Optional server uri when referencing an external node.	`''`

Returns:

Type	Description
`MaybeAwaitable[StatusCode]`	The individual StatusCode, or an awaitable resolving to it.
`MaybeAwaitable[StatusCode]`	Rejected mutations, including duplicate local edges, return bad statuses.

Raises:

Type	Description
`StatusCodeError`	The service failed.
`TypeError`	An argument has an invalid Python type.
`ValueError`	An argument cannot be converted to a node id or enum.

deleteReference ¶

deleteReference(
    source,
    reftype,
    target,
    forward=True,
    deleteBidirectional=True,
)

Delete a reference between two nodes.

Parameters:

Name	Type	Description	Default
`source`	`NodeIdLike`	The source node id for the reference.	required
`reftype`	`NodeIdLike`	The reference type id.	required
`target`	`NodeIdLike \| ExpandedNodeId`	The target node id.	required
`forward`	`bool`	If `True`, delete the forward reference.	`True`
`deleteBidirectional`	`bool`	If `True`, also delete the reverse reference.	`True`

Returns:

Type	Description
`MaybeAwaitable[StatusCode]`	The individual StatusCode, or an awaitable resolving to it.
`MaybeAwaitable[StatusCode]`	Rejected deletions return non-Good statuses, including
`MaybeAwaitable[StatusCode]`	UNCERTAIN_REFERENCE_NOT_DELETED for an absent edge.

Raises:

Type	Description
`StatusCodeError`	The service failed.
`TypeError`	An argument has an invalid Python type.
`ValueError`	An argument cannot be converted to a node id.

createSubscription ¶

createSubscription(
    publishingInterval=100.0,
    lifetimeCount=36000,
    maxKeepaliveCount=10,
    maxNotificationsPerPublish=10,
    publishingEnabled=True,
    *,
    onCreated=None,
    onStatusChange=None,
    onDeleted=None
)

Create a subscription to monitor data or events.

Parameters:

Name	Type	Description	Default
`publishingInterval`	`float`	The desired publishing interval in milliseconds.	`100.0`
`lifetimeCount`	`int`	The subscription lifetime count.	`36000`
`maxKeepaliveCount`	`int`	The maximum keepalive count.	`10`
`maxNotificationsPerPublish`	`int`	The maximum number of notifications per publish.	`10`
`publishingEnabled`	`bool`	Whether the subscription is initially enabled.	`True`
`onCreated`	`Callable[['o6.subscription.Subscription', CreateSubscriptionResponse], MaybeAwaitable[None]] \| None`	Optional callback invoked with `(subscription, response)` once the server has acknowledged subscription creation.	`None`
`onStatusChange`	`Callable[['o6.subscription.Subscription', StatusChangeNotification], MaybeAwaitable[None]] \| None`	Optional callback invoked with `(subscription, notification)` when the server publishes a `StatusChangeNotification` for this subscription.	`None`
`onDeleted`	`Callable[['o6.subscription.Subscription'], MaybeAwaitable[None]] \| None`	Optional callback invoked with `(subscription,)` when the subscription is destroyed — explicitly via `delete()`, or implicitly on session close / disconnect.	`None`

Returns:

Type	Description
`MaybeAwaitable[Subscription]`	A `o6.subscription.Subscription` object representing the created subscription.

monitor ¶

monitor(
    target,
    callback=None,
    samplingInterval=100.0,
    *,
    valueOnly=True,
    subscription=None,
    filter=None,
    monitoringMode=ns0.datatypes.MonitoringMode.REPORTING,
    queueSize=1,
    discardOldest=True,
    onCreated=None,
    onDeleted=None
)

Monitor data changes on one or more nodes.

Parameters:

Name	Type	Description	Default
`target`	`NodeIdLike \| ReadValueId \| list[NodeIdLike \| ReadValueId]`	A node id, [ReadValueId][o6.ns.ns0.datatypes.ReadValueId], or list thereof to monitor.	required
`callback`	`DataChangeCallback \| None`	Optional callback invoked for each data change. If `None`, a default callback that prints `o6.subscription.MonitoredItem {id}: {value}` to stdout is used.	`None`
`samplingInterval`	`float`	The requested sampling interval in milliseconds.	`100.0`
`valueOnly`	`bool`	If `True` (default), the callback receives the unwrapped value. If `False`, it receives the full DataValue.	`True`
`subscription`	`Subscription \| None`	Optional subscription to attach the monitored items to. If `None` (default), the clients' default subscription is used. A subscription owned by another client raises `ValueError`.	`None`
`filter`	`DataChangeFilter \| None`	Optional [DataChangeFilter][o6.ns.ns0.datatypes.DataChangeFilter] to control triggering.	`None`
`monitoringMode`	`MonitoringMode`	Monitoring mode for the item (default: `REPORTING`).	`REPORTING`
`queueSize`	`int`	Requested queue size (default: `1`).	`1`
`discardOldest`	`bool`	Whether to discard the oldest entry when the queue is full (default: `True`).	`True`
`onCreated`	`CreatedCallback \| None`	Optional lifecycle callback; see `o6.subscription.MonitoredItem._data_change`.	`None`
`onDeleted`	`DeletedCallback \| None`	Optional lifecycle callback; see `o6.subscription.MonitoredItem._data_change`.	`None`

Returns:

Type	Description
`MaybeAwaitable[MonitoredItem \| list[MonitoredItem]]`	A monitored item or list of monitored items created for the target nodes.

monitorEvent ¶

monitorEvent(
    nodeId,
    callback,
    filter=None,
    *,
    subscription=None,
    monitoringMode=ns0.datatypes.MonitoringMode.REPORTING,
    queueSize=100,
    discardOldest=True,
    onCreated=None,
    onDeleted=None
)

Monitor events on a node.

Callbacks receive a dict[str, Any] keyed by selected event-filter paths, such as "/Message" or "/ConditionName/Id", optionally preceded by the monitored item handle.

Parameters:

Name	Type	Description	Default
`nodeId`	`NodeIdLike`	The node id to monitor for events.	required
`callback`	`EventCallback`	Callback invoked for each matching event.	required
`filter`	`EventFilter \| str \| None`	Optional event filter or filter expression string. If `None`, a default filter selecting `EventId`, `EventType`, `SourceName`, `Time`, `Message`, and `Severity` is used.	`None`
`subscription`	`Subscription \| None`	Optional subscription to attach the monitored item to. Defaults to `defaultSubscription`; a subscription owned by another client raises `ValueError`.	`None`
`monitoringMode`	`MonitoringMode`	Monitoring mode for the item (default: `REPORTING`).	`REPORTING`
`queueSize`	`int`	Requested queue size (default: `100`).	`100`
`discardOldest`	`bool`	Whether to discard the oldest entry when the queue is full (default: `True`).	`True`
`onCreated`	`CreatedCallback \| None`	Optional lifecycle callback; see `o6.subscription.MonitoredItem._event`.	`None`
`onDeleted`	`DeletedCallback \| None`	Optional lifecycle callback; see `o6.subscription.MonitoredItem._event`.	`None`

Returns:

Type	Description
`MaybeAwaitable[MonitoredItem]`	The created monitored event item.

Client¶

Client ¶

Attributes¶

config instance-attribute ¶

root instance-attribute ¶

objects instance-attribute ¶

types instance-attribute ¶

views instance-attribute ¶

T class-attribute instance-attribute ¶

loop property ¶

state property ¶

connected property ¶

onGlobalNotification property writable ¶

onLifecycleNotification property writable ¶

onServiceNotification property writable ¶

subscriptions property ¶

defaultSubscription property ¶

Functions¶

__init__ ¶

__del__ ¶

connect ¶

disconnect ¶

startReverseConnect ¶

activateCurrentSession ¶

activateSession ¶

__enter__ ¶

__exit__ ¶

__aenter__ async ¶

__aexit__ async ¶

__getitem__ ¶

serviceFindServers ¶

serviceFindServersOnNetwork ¶

serviceGetEndpoints ¶

invalidateNodeCache ¶

serviceAddNodes ¶

serviceDeleteNodes ¶

serviceAddReferences ¶

serviceDeleteReferences ¶

serviceBrowse ¶

serviceBrowseNext ¶

serviceTranslateBrowsePathsToNodeIds ¶

serviceRegisterNodes ¶

serviceUnregisterNodes ¶

serviceRead ¶

serviceHistoryRead ¶

serviceWrite ¶

serviceHistoryUpdate ¶

serviceCall ¶

getRemoteDataTypes ¶

updateRemoteNamespaces ¶

getEndpoints ¶

findServers ¶

findServersOnNetwork ¶

read ¶

write ¶

call ¶

browse ¶

browsePage ¶

browseNext ¶

translateBrowsePathsToNodeIds ¶

browseSimplifiedBrowsePaths ¶

browseInteractive ¶

historyRead ¶

historyUpdateInsert ¶

historyUpdateReplace ¶

historyUpdateDelete ¶

addObject ¶

addVariable ¶

addVariableNode ¶

addVariableTypeNode ¶

addObjectNode ¶

addObjectTypeNode ¶

addViewNode ¶

addReferenceTypeNode ¶

addDataTypeNode ¶

addMethodNode ¶

deleteNode ¶

addReference ¶

deleteReference ¶

createSubscription ¶

config `instance-attribute` ¶

root `instance-attribute` ¶

objects `instance-attribute` ¶

types `instance-attribute` ¶

views `instance-attribute` ¶

T `class-attribute` `instance-attribute` ¶

loop `property` ¶

state `property` ¶

connected `property` ¶

onGlobalNotification `property` `writable` ¶

onLifecycleNotification `property` `writable` ¶

onServiceNotification `property` `writable` ¶

subscriptions `property` ¶

defaultSubscription `property` ¶

init ¶

del ¶

enter ¶

exit ¶

aenter `async` ¶

aexit `async` ¶

getitem ¶