# Subscriptions

<dl class="api-definition">
<dt>Concept</dt>
<dd><a href="/docs/development/opcua/client/subscriptions">Subscriptions</a></dd>
</dl>

| Type | Description |
|---|---|
| [OpcClient](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/) | Provides session based methods to access OPC UA server services. |
| [OpcDataChangeFilter](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatachangefilter/) | Defines the conditions under which a data change notification is to be reported. |
| [OpcDataChangeReceivedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcdatachangereceivedeventargs/) | Provides the event data for the [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/datachangereceived), [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#datachangereceived) and [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/members#datachangereceived) events. |
| [OpcDataChangeReceivedEventHandler](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcdatachangereceivedeventhandler/) | Represents the method that will handle [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/datachangereceived), [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#datachangereceived) and [DataChangeReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/members#datachangereceived) events. |
| [OpcDataChangeTrigger](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatachangetrigger/) | Specifies the conditions under which a data change notification is to be reported. |
| [OpcDeadbandType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdeadbandtype/) | Defines how value changes shall be classified as part of the 'deadband' or the 'liveband'. |
| [OpcEventReceivedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opceventreceivedeventargs/) | Provides the event data for the [EventReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/eventreceived), [EventReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#eventreceived) and [EventReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/members#eventreceived) events. |
| [OpcEventReceivedEventHandler](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opceventreceivedeventhandler/) | Represents the method that will handle [EventReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/eventreceived), [EventReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#eventreceived) and [EventReceived](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/members#eventreceived) events. |
| [OpcMonitoredItem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/) | Represents a node and one of its attributes (= node data) to subscribe to monitor data changes or events on the node. |
| [OpcMonitoredItemCollection](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditemcollection/) | Represents a collection of [OpcMonitoredItem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/) instances keyed by their [ClientID](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/members#clientid). |
| [OpcMonitoredItemQueueMode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditemqueuemode/) | Defines how generated notification data items shall be stored within the notification queue. |
| [OpcMonitoringMode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmonitoringmode/) | Defines the different modes supported to monitor a node-attribute pair (= monitored item). |
| [OpcNodeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnodeid/) | Defines an identifier for a node in the address space of an OPC UA Server. |
| [OpcNotification](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnotification/) | Represents a notification message a client received for a subscription, as defined by the NotificationMessage of OPC UA. |
| [OpcNotificationFailedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcnotificationfailedeventargs/) | Provides the event data for the [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/notificationfailed) and [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#notificationfailed) events. |
| [OpcNotificationFailedEventHandler](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcnotificationfailedeventhandler/) | Represents the method that will handle the [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/notificationfailed) and [NotificationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/members#notificationfailed) events. |
| [OpcSubscribeDataChange](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscribedatachange/) | Represents a single OPC UA service command which addresses the 'CreateSubscription' service to define a single monitored item to monitor data changes through a subscription using the setup represented. |
| [OpcSubscribeEvent](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscribeevent/) | Represents a single OPC UA service command which addresses the 'CreateSubscription' service to define a single monitored item to monitor events through a subscription using the setup represented. |
| [OpcSubscription](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/) | Provides mechanisms to monitor a set of attributes (= node data) and (node-related) events using notifications being reported from the server to the client. |
| [OpcSubscriptionSetup](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscriptionsetup/) | Defines a set of properties which can be used to create a whole [OpcSubscription](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcsubscription/) including its [OpcMonitoredItem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcmonitoreditem/) objects. |