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WorkflowHostingEndpoint.OnGetInstanceId Method

Override to return the instance ID for the workflow instance being created.

Namespace:  System.ServiceModel.Activities
Assembly:  System.ServiceModel.Activities (in System.ServiceModel.Activities.dll)

protected internal virtual Guid OnGetInstanceId(
	Object[] inputs,
	OperationContext operationContext


Type: System.Object[]
The inputs to the service operation.
Type: System.ServiceModel.OperationContext
The operation context of the service operation.

Return Value

Type: System.Guid
The instance ID for the newly created workflow instance.

Return null to indicate that an instance ID should be automatically generated.

The following example shows how to implement the OnGetInstanceId(Object[], OperationContext) method.

protected override Guid OnGetInstanceId(object[] inputs, OperationContext operationContext)
    //Create was called by client
    if (operationContext.IncomingMessageHeaders.Action.EndsWith("Create"))
        return Guid.Empty;
    //CreateWithInstanceId was called by client
    else if (operationContext.IncomingMessageHeaders.Action.EndsWith("CreateWithInstanceId"))
        return (Guid)inputs[1];
        throw new InvalidOperationException("Invalid Action: " + operationContext.IncomingMessageHeaders.Action);

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.