Hi

401 unauthorized errors are usually related to Kerberos, please check your Kerberos configuration and settings.

Are you referring to exposing an existing Smartobject as a wcf/rest endpoint similar to the image below (Smartobject Services):

I am not familiar with SOAPUI, but how is the authentication method/mode specified.  Instead if you were to create a C# console app, add the service and test, do you see the same behavior?

Using WCF Endpoint to start the process

            StartProcessSMO_StartProcessSMOSvcClient client = new StartProcessSMO_StartProcessSMOSvcClient();

            // Use the 'client' variable to call operations on the service.

            StartProcessSMO_StartProcessSMO processSMO = new StartProcessSMO_StartProcessSMO();

            processSMO.Folio = "fromConsoleApp";

            processSMO.Priority = "0";

            client.ClientCredentials.Windows.AllowedImpersonationLevel = System.Security.Principal.TokenImpersonationLevel.Impersonation;

            client.StartProcessSMO_StartProcessSMOSvc_StartProcess(processSMO);

            // Always close the client.

            client.Close();

https://help.k2.com/onlinehelp/k2blackpearl/devref/4.6.7/webframe.html#URIs_for_WCF.html

“POST” to a rest service

            Uri address = new Uri("http://k2.denallix.com:8888/SmartObjectServices/rest/Workflow/StartProcessSMO/StartProcessSMO/StartProcessSMO Process Instances/Start Process");

            // create the XML Returned variable

            string XML_Return;

            // Create the web request

            HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;

            // Assign Credentials

            request.Credentials = CredentialCache.DefaultCredentials;

            // Set type to POST

            request.Method = "POST";

            request.ContentType = "application/xml";

            // Create the data we want to send

            string SO_Create_POST = "<StartProcessSMO_StartProcessSMO><Folio>Rest Call</Folio><Priority>1</Priority></StartProcessSMO_StartProcessSMO>";

            StringBuilder data = new StringBuilder();

            data.Append(SO_Create_POST);

            // Create a byte array of the data we want to send

            byte;] byteData = UTF8Encoding.UTF8.GetBytes(data.ToString());

            // Set the content length in the request headers

            request.ContentLength = byteData.Length;

            // Write data

            using (Stream postStream = request.GetRequestStream())

            {

                postStream.Write(byteData, 0, byteData.Length);

            }

            // Get response

            using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)

            {

                // Get the response stream

                StreamReader reader = new StreamReader(response.GetResponseStream());

                // assign resonse the XML Returned variable

                XML_Return = reader.ReadToEnd();

            }

https://help.k2.com/onlinehelp/k2blackpearl/devref/4.6.7/webframe.html#Using_K2_Web_Services_with_ASP.NET_Applications_REST.html