# Test clients

<dl class="api-definition">
<dt>Concept</dt>
<dd><a href="/docs/development/opcua/client/testing">Test clients</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. |
| [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. |
| [OpcDataVariableNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatavariablenode/) | Provides a node to represent complex data structures expose their information as complex data types, as well as components in the address space. |
| [OpcMethodNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmethodnode/) | Defines a method node. |
| [OpcObjectNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcobjectnode/) | Defines a logical unit to represent more complex information as a [OpcVariableNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcvariablenode/). |
| [OpcServer](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserver/) | Represents an OPC UA server which provides the address space defined by its [NodeManagers](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserver/members#nodemanagers) to its clients. |
| [OpcStatus](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcstatus/) | Provides information about the outcome of an operation. |