/// <summary>
/// Dispatches a notification message produced by a subscription.
/// </summary>
private void DispatchMessage(Subscription subscription, NotificationMessage notification)
{
lock (m_messages)
{
for (LinkedListNode<QueuedRequest> node = m_requests.First; node != null; node = node.Next)
{
// wake up timed out requests and force them to return a fault.
if (node.Value.Timeout < DateTime.UtcNow)
{
node.Value.Signal.Set();
m_requests.Remove(node);
continue;
}
// check for a request that matches the session.
if (Object.ReferenceEquals(subscription.Session, node.Value.Session))
{
// pass the message to the request and wake up the request thread.
node.Value.SubscriptionId = subscription.Id;
node.Value.Message = notification;
node.Value.Signal.Set();
m_requests.Remove(node);
return;
}
}
// messages only go on the publish queue if no threads are waiting.
QueuedMessage message = new QueuedMessage();
message.Session = subscription.Session;
message.Subscription = subscription;
message.Message = notification;
m_messages.AddLast(message);
// ensure queue does not grow too large.
while (m_messages.Count > 50)
{
m_messages.RemoveFirst();
}
}
}
/// <summary>
/// Creates a subscription that can be used to recieve data change or event notifications.
/// </summary>
public CreateSubscriptionResponseMessage CreateSubscription(CreateSubscriptionMessage request)
{
try
{
lock (m_lock)
{
// verify the session.
Session session = VerifySession(request.RequestHeader, false);
// create a new subscription.
Subscription subscription = new Subscription();
uint subscriptionId;
double publishingInterval;
uint lifetimeCount;
uint keepAliveCount;
// the subscription validates the parameters and throws exceptions on error.
subscription.Create(
session,
m_nodeManager,
request.RequestedPublishingInterval,
request.RequestedLifetimeCount,
request.RequestedMaxKeepAliveCount,
request.MaxNotificationsPerPublish,
request.PublishingEnabled,
request.Priority,
out subscriptionId,
out publishingInterval,
out lifetimeCount,
out keepAliveCount);
// save the subscription.
m_subscriptions.Add(subscriptionId, subscription);
// start the publish thread if it has not already been started.
if (m_subscriptions.Count == 1)
{
ThreadPool.QueueUserWorkItem(PublishSubscriptions);
}
// return the response.
CreateSubscriptionResponseMessage response = new CreateSubscriptionResponseMessage();
response.ResponseHeader = CreateResponseHeader(request.RequestHeader);
response.SubscriptionId = subscriptionId;
response.RevisedPublishingInterval = publishingInterval;
response.RevisedLifetimeCount = lifetimeCount;
response.RevisedMaxKeepAliveCount = keepAliveCount;
return response;
}
}
catch (Exception e)
{
throw CreateSoapFault(request.RequestHeader, e);
}
}