OPC Studio User's Guide and Reference
HostNames Property (AbstractEasyUAClientServerApplication)



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.Application Namespace > AbstractEasyUAClientServerApplication Class : HostNames Property
A collection of host names for the application instance.
Syntax
'Declaration
 
Public MustOverride ReadOnly Property HostNames As StringCollection
'Usage
 
Dim instance As AbstractEasyUAClientServerApplication
Dim value As StringCollection
 
value = instance.HostNames
public abstract StringCollection HostNames {get;}
public:
abstract property StringCollection^ HostNames {
   StringCollection^ get();
}

Property Value

The value of this property cannot be null (Nothing in Visual Basic).

The individual elements of the property value cannot be null (Nothing in Visual Basic).

Remarks

The getter method of this property is pure, i.e. it does not have observable side effects.

This method or property does not throw any exceptions, aside from execution exceptions such as System.Threading.ThreadAbortException or System.OutOfMemoryException.

Host names are only relevant for servers.

When no host names are specified, the component uses default host names instead. For server applications, the default host names consist of known DNS and NetBIOS names and IPv4 and IPv6 addresses of the local host. For applications that are not servers, the default host names are empty.

The host names come into play in following situations:

From UA-.NETStandard comments: "These list the alternate host names (via firewalls, multiple NICs etc.) that can be used to communicate with the server. The URL used by the client when calling FindServers/GetEndpoints or CreateSession will be used to filter the list of endpoints returned by checking for alternate host names that match the domain in the URL provided by the client.
Note that any additional domains should be listed in the server's certificate. If they are left out the client make refuse to connect because it has no way to know if the alternate domain was authorized by the server administrator."

From OPC UA specification: "Servers shall specify a partial or a fully qualified dNSName or a static IPAddress which identifies the machine where the application Instance runs. Additional dNSNames may be specified if the machine has multiple names."

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also