Opc.Ua.Server.Subscription.Acknowledge C# (CSharp) Method

        public ServiceResult Acknowledge(OperationContext context, uint sequenceNumber)
        {
            lock (m_lock)
            {
                // check session.
                VerifySession(context);

                // clear lifetime counter.
                ResetLifetimeCount();

                // find message in queue.
                for (int ii = 0; ii < m_sentMessages.Count; ii++)
                {
                    if (m_sentMessages[ii].SequenceNumber == sequenceNumber)
                    {
                        if (m_lastSentMessage > ii)
                        {
                            m_lastSentMessage--;
                        }

                        m_sentMessages.RemoveAt(ii);
                        return null;
                    }
                }

                if (sequenceNumber == 0)
                {
                    return StatusCodes.BadSequenceNumberInvalid;
                }

                // TraceState("ACK " + sequenceNumber.ToString());

                // message not found.
                return StatusCodes.BadSequenceNumberUnknown;
            }
        }