/// <summary>
/// Creates a new subscription for the specified topic.
/// </summary>
/// <typeparam name="T">The type of data the subscription is expected to return.</typeparam>
/// <typeparam name="TPayloadConverter">The type of the converter that can convert from bytes to the type T.</typeparam>
/// <param name="topic">The topic to subscribe to.</param>
/// <param name="qos">The QOS level to subscribe at.</param>
/// <returns>An observable that yields messages when they arrive.</returns>
private IObservable <MqttReceivedMessage <T> > CreateNewSubscription <T, TPayloadConverter>(string topic, MqttQos qos)
where TPayloadConverter : IPayloadConverter <T>, new()
{
Log.Info(m => m("Creating subscription for topic {0} @ QOS {1}.", topic, qos));
// Get an ID that represents the subscription. We will use this same ID for unsubscribe as well.
var msgId = messageIdentifierDispenser.GetNextMessageIdentifier("subscriptions");
// create a new observable that is used to yield messages
// that arrive for the topic.
var observable = CreateObservableForSubscription(topic, msgId);
var sub = new Subscription {
Topic = topic,
Qos = qos,
MessageIdentifier = msgId,
CreatedTime = DateTime.Now,
Observable = observable,
};
pendingSubscriptions.Add(sub.MessageIdentifier, sub);
// build a subscribe message for the caller and send it off to the broker.
var msg = new MqttSubscribeMessage().WithMessageIdentifier(sub.MessageIdentifier)
.ToTopic(sub.Topic)
.AtQos(sub.Qos);
connectionHandler.SendMessage(msg);
return(WrapSubscriptionObservable <T, TPayloadConverter>(topic, sub.Observable));
}
/// <summary>
/// Pings the message broker if there has been no activity for the specified amount of idle time.
/// </summary>
/// <param name="state"></param>
private void PingRequired(object state)
{
// if we can't get the montor then the connection has been / is currently being disposed, so
// we don't want to do a ping (the connection handler might no longer be valid)
if (Monitor.TryEnter(shutdownPadlock))
{
try {
var pingMsg = new MqttPingRequestMessage();
connectionHandler.SendMessage(pingMsg);
} finally {
Monitor.Exit(shutdownPadlock);
}
}
}
/// <summary>
/// Publish a message to the broker on the specified topic.
/// </summary>
/// <param name="topic">The topic to send the message to.</param>
/// <param name="qualityOfService">The QOS to use when publishing the message.</param>
/// <param name="data">The message to send.</param>
/// <returns>The message identifier assigned to the message.</returns>
public short Publish<T, TPayloadConverter>(string topic, MqttQos qualityOfService, T data)
where TPayloadConverter : IPayloadConverter<T>, new() {
var msgId = messageIdentifierDispenser.GetNextMessageIdentifier(String.Format("Topic:{0}", topic));
Log.DebugFormat("Publishing message ID {0} on topic {1} using QOS {2}", msgId, topic, qualityOfService);
var converter = GetPayloadConverter<TPayloadConverter>();
var msg = new MqttPublishMessage()
.ToTopic(topic)
.WithMessageIdentifier(msgId)
.WithQos(qualityOfService)
.PublishData(converter.ConvertToBytes(data));
// QOS level 1 or 2 messages need to be saved so we can do the ack processes
if (qualityOfService == MqttQos.AtLeastOnce || qualityOfService == MqttQos.ExactlyOnce) {
publishedMessages.Add(msgId, msg);
}
connectionHandler.SendMessage(msg);
return msgId;
}
/// <summary>
/// Publish a message to the broker on the specified topic.
/// </summary>
/// <param name="topic">The topic to send the message to.</param>
/// <param name="payload">The message to send.</param>
/// <returns>The message identifier assigned to the message.</returns>
public short Publish <TDataConverter>(string topic, MqttQos qualityOfService, object data)
where TDataConverter : IPublishDataConverter
{
short msgID = MessageIdentifierDispenser.GetNextMessageIdentifier(String.Format("Topic:{0}", topic));
IPublishDataConverter converter = GetPublishDataConverter <TDataConverter>();
MqttPublishMessage msg = new MqttPublishMessage()
.ToTopic(topic)
.WithMessageIdentifier(msgID)
.WithQos(qualityOfService)
.PublishData(converter.ConvertToBytes(data));
// QOS level 1 or 2 messages need to be saved so we can do the ack processes
if (qualityOfService == MqttQos.AtLeastOnce || qualityOfService == MqttQos.ExactlyOnce)
{
publishedMessages.Add(msgID, msg);
}
connectionHandler.SendMessage(msg);
return(msgID);
}
/// <summary>
/// Registers a new subscription with the subscription manager.
/// </summary>
/// <param name="topic"></param>
/// <param name="qos"></param>
/// <returns>The subscription message identifier.</returns>
internal short RegisterSubscription <TPublishDataConverter>(string topic, MqttQos qos)
where TPublishDataConverter : IPublishDataConverter
{
// check we don't have a pending subscription request for the topic.
var pendingSubs = from ps in pendingSubscriptions.Values
where ps.Topic.Equals(topic)
select ps;
if (pendingSubs.Count <Subscription>() > 0)
{
throw new ArgumentException("There is already a pending subscription for this topic");
}
// no pending subscription, if we already have a subscription then throw it back out as well
if (subscriptions.ContainsKey(topic))
{
// TODO: we might want to treat this as an ignore/silent confirm because they will be receiving messages for the topic already
throw new ArgumentException("You are already subscribed for this topic");
}
// Add a pending subscription...
Subscription sub = new Subscription()
{
Topic = topic,
Qos = qos,
MessageIdentifier = MessageIdentifierDispenser.GetNextMessageIdentifier("subscriptions"),
CreatedTime = DateTime.Now,
DataProcessor = Activator.CreateInstance <TPublishDataConverter>()
};
pendingSubscriptions.Add(sub.MessageIdentifier, sub);
// build a subscribe message for the caller.
MqttSubscribeMessage msg = new MqttSubscribeMessage()
.WithMessageIdentifier(sub.MessageIdentifier)
.ToTopic(sub.Topic)
.AtQos(sub.Qos);
connectionHandler.SendMessage(msg);
return(msg.VariableHeader.MessageIdentifier);
}
