Opc.Ua.Server.SubscriptionManager.Publish C# (CSharp) Method

        public NotificationMessage Publish(
            OperationContext                      context, 
            SubscriptionAcknowledgementCollection subscriptionAcknowledgements,
            AsyncPublishOperation                 operation,
            out uint                              subscriptionId, 
            out UInt32Collection                  availableSequenceNumbers, 
            out bool                              moreNotifications, 
            out StatusCodeCollection              acknowledgeResults, 
            out DiagnosticInfoCollection          acknowledgeDiagnosticInfos)
        {
            availableSequenceNumbers = null;
            moreNotifications = false;

            // get publish queue for session.
            SessionPublishQueue queue = null;
            
            lock (m_lock)
            {
                if (!m_publishQueues.TryGetValue(context.Session.Id, out queue))
                {
                    if (m_subscriptions.Count == 0)
                    {
                        throw new ServiceResultException(StatusCodes.BadNoSubscription);
                    }

                    throw new ServiceResultException(StatusCodes.BadSessionClosed);
                }
            }

            // acknowlege previous messages.
            queue.Acknowledge(
                context,
                subscriptionAcknowledgements, 
                out acknowledgeResults,
                out acknowledgeDiagnosticInfos);
            
            // update diagnostics.
            if (context.Session != null)
            {
                lock (context.Session.DiagnosticsLock)
                {
                    SessionDiagnosticsDataType diagnostics = context.Session.SessionDiagnostics;
                    diagnostics.CurrentPublishRequestsInQueue++;
                }
            }

            // save results for asynchrounous operation.
            if (operation != null)
            {
                operation.Response.Results = acknowledgeResults;
                operation.Response.DiagnosticInfos = acknowledgeDiagnosticInfos;
            }

            // gets the next message that is ready to publish.
            NotificationMessage message = GetNextMessage(
                context,
                queue,
                operation,
                out subscriptionId,
                out availableSequenceNumbers,
                out moreNotifications);

            // if no message and no async operation then a timeout occurred.
            if (message == null && operation == null)
            {
                throw new ServiceResultException(StatusCodes.BadTimeout);
            }
            
            // return message.
            return message;
        }