IDisposableIEnumerableIEnumeratorThis convenience class abstracts away from much of the detail involved in receiving messages from a queue or an exchange.
Once created, the Subscription consumes from a queue (using a QueueingBasicConsumer). Received deliveries can be retrieved by calling Next(), or by using the Subscription as an IEnumerator in, for example, a foreach loop.
Note that if the "noAck" option is enabled (which it is by default), then received deliveries are automatically acked within the server before they are even transmitted across the network to us. Calling Ack() on received events will always do the right thing: if "noAck" is enabled, nothing is done on an Ack() call, and if "noAck" is disabled, IModel.BasicAck() is called with the correct parameters.
| Flags | Type | Name | Summary |
|---|---|---|---|
| public | IBasicConsumer |
Consumer (r)
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Retrieve the IBasicConsumer that is receiving the messages from the server for us. Normally, you will not need to access this property - use Next() and friends instead. |
| public | |
ConsumerTag (r)
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Retrieve the consumer-tag that this subscription is using. Will usually be a server-generated name. |
| public | BasicDeliverEventArgs |
LatestEvent (r)
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Returns the most recent value returned by Next(), or null when either no values have been retrieved yet, the end of the subscription has been reached, or the most recent value has already been Ack()ed. See also the documentation for Ack(). |
| public | IModel |
Model (r)
|
Retrieve the IModel our subscription is carried by. |
| public | |
NoAck (r)
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Returns true if we are in "noAck" mode, where calls to Ack() will be no-ops, and where the server acks messages before they are delivered to us. Returns false if we are in a mode where calls to Ack() are required, and where such calls will actually send an acknowledgement message across the network to the server. |
| public | |
QueueName (r)
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Retrieve the queue name we have subscribed to. |
| Flags | Name | Summary |
|---|---|---|
| public | Subscription(IModel model, string queueName, bool noAck)
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Creates a new Subscription, with full control over both "noAck" mode and the name of the queue. |
| public | Subscription(IModel model, string queueName)
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Creates a new Subscription in "noAck" mode, consuming from a named queue. |
| Flags | Name | Summary |
|---|---|---|
| public | void Ack()
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If LatestEvent is non-null, passes it to Ack(BasicDeliverEventArgs). Causes LatestEvent to become null. |
| public | void Ack(BasicDeliverEventArgs evt)
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If we are not in "noAck" mode, calls IModel.BasicAck with the delivery-tag from the passed in event; otherwise, sends nothing to the server. In both cases, if the passed-in event is the same as LatestEvent (by pointer comparison), sets LatestEvent to null. |
| public | void Close()
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Closes this Subscription, cancelling the consumer record in the server. |
| public | bool Next(int millisecondsTimeout, out BasicDeliverEventArgs result)
|
Retrieves the next incoming delivery in our subscription queue, or times out after a specified number of milliseconds. |
| public | BasicDeliverEventArgs Next()
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Retrieves the next incoming delivery in our subscription queue. |
public Subscription(IModel model, string queueName, bool noAck)
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public Subscription(IModel model, string queueName)
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public void Ack()
| Flags | public |
|---|---|
| Return type | |
public void Ack(BasicDeliverEventArgs evt)
| Flags | public | ||||
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public void Close()
| Flags | public |
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| Return type | |
public bool Next(int millisecondsTimeout, out BasicDeliverEventArgs result)
| Flags | public | ||||||
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| Return type | |
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| Parameters |
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Returns false only if the timeout expires before either a delivery appears or the end-of-stream is reached. If false is returned, the out parameter "result" is set to null, but LatestEvent is not updated.
Returns true to indicate a delivery or the end-of-stream.
If a delivery is already waiting in the queue, or one arrives before the timeout expires, it is removed from the queue and placed in the "result" out parameter. If the end-of-stream is detected before the timeout expires, "result" is set to null.
Whenever this method returns true, it updates LatestEvent to the value placed in "result" before returning.
End-of-stream can arise through the action of the Subscription.Close() method, or through the closure of the IModel or its underlying IConnection.
This method does not acknowledge any deliveries at all (but in "noAck" mode, the server will have auto-acknowledged each event before it is even sent across the wire to us).
A timeout of -1 (i.e. System.Threading.Timeout.Infinite) will be interpreted as a command to wait for an indefinitely long period of time for an item or the end of the stream to become available. Usage of such a timeout is equivalent to calling Next() with no arguments (modulo predictable method signature differences).
public BasicDeliverEventArgs Next()
| Flags | public |
|---|---|
| Return type | BasicDeliverEventArgs |
Returns null when the end of the stream is reached and on every subsequent call. End-of-stream can arise through the action of the Subscription.Close() method, or through the closure of the IModel or its underlying IConnection.
Updates LatestEvent to the value returned.
Does not acknowledge any deliveries at all (but in "noAck" mode, the server will have auto-acknowledged each event before it is even sent across the wire to us).