Opc.Ua.Client.Session.UpdateSession C# (CSharp) Method

        public void UpdateSession(IUserIdentity identity, StringCollection preferredLocales)
        {
            byte[] serverNonce = null;

            lock (SyncRoot)
            {
                // check connection state.
                if (!Connected)
                {
                    throw new ServiceResultException(StatusCodes.BadInvalidState, "Not connected to server.");
                }

                // get current nonce.
                serverNonce = m_serverNonce;

                if (preferredLocales == null)
                {
                    preferredLocales = m_preferredLocales;
                }
            }
            
            // get the identity token.
            UserIdentityToken identityToken = null;
            SignatureData userTokenSignature = null;

            string securityPolicyUri = m_endpoint.Description.SecurityPolicyUri;
  
            // create the client signature.
            byte[] serverCertificateData = null;
            if (m_serverCertificate != null)
            {
                serverCertificateData = m_serverCertificate.GetRawCertData();
            }
            // create the client signature.
            byte[] dataToSign = Utils.Append(serverCertificateData, serverNonce);
            SignatureData clientSignature = SecurityPolicies.Sign(m_instanceCertificate, securityPolicyUri, dataToSign);
            
            // choose a default token.            
            if (identity == null)
            {
                identity = new UserIdentity();
            }

            // check that the user identity is supported by the endpoint.
            UserTokenPolicy identityPolicy = m_endpoint.Description.FindUserTokenPolicy(identity.TokenType, identity.IssuedTokenType);

            if (identityPolicy == null)
            {
                throw ServiceResultException.Create(
                    StatusCodes.BadUserAccessDenied,
                    "Endpoint does not supported the user identity type provided.");
            }

            // select the security policy for the user token.
            securityPolicyUri = identityPolicy.SecurityPolicyUri;

            if (String.IsNullOrEmpty(securityPolicyUri))
            {
                securityPolicyUri = m_endpoint.Description.SecurityPolicyUri;
            }
        
            // sign data with user token.
            identityToken = identity.GetIdentityToken();  
            identityToken.PolicyId = identityPolicy.PolicyId;
            userTokenSignature = identityToken.Sign(dataToSign, securityPolicyUri);
                
            // encrypt token.
            identityToken.Encrypt(m_serverCertificate, serverNonce, securityPolicyUri);

            // send the software certificates assigned to the client.
            SignedSoftwareCertificateCollection clientSoftwareCertificates = GetSoftwareCertificates();

            StatusCodeCollection certificateResults = null;
            DiagnosticInfoCollection certificateDiagnosticInfos = null;

            // activate session.
            ActivateSession(
                null,
                clientSignature,
                clientSoftwareCertificates,
                preferredLocales,
                new ExtensionObject(identityToken),
                userTokenSignature,
                out serverNonce,
                out certificateResults,
                out certificateDiagnosticInfos);

            // save nonce and new values.
            lock (SyncRoot)
            {
                if (identity != null)
                {
                    m_identity = identity;
                }

                m_serverNonce      = serverNonce;
                m_preferredLocales = preferredLocales;

                // update system context.
                m_systemContext.PreferredLocales = m_preferredLocales;
                m_systemContext.SessionId = this.SessionId;
                m_systemContext.UserIdentity = identity;
            }
        }