C# Class RabbitMQ.Client.MessagePatterns.Subscription

Manages a subscription to a queue or exchange.

This 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.

Inheritance: IEnumerable, IEnumerator, IDisposable
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Protected Properties

Property Type Description
m_consumer RabbitMQ.Client.Events.EventingBasicConsumer
m_eventLock object

Private Properties

Property Type Description
HandleConsumerCancelled void
IDisposable void
IEnumerable IEnumerator
IEnumerator bool
IEnumerator void
QueueAdd void

Public Methods

Method Description
Ack ( ) : void

If LatestEvent is non-null, passes it to Ack(BasicDeliverEventArgs). Causes LatestEvent to become null.

Ack ( RabbitMQ.Client.Events.BasicDeliverEventArgs evt ) : void

If we are not in "autoAck" mode, calls IModel.BasicAck with the delivery-tag from evt; otherwise, sends nothing to the server. if evt is the same as LatestEvent by pointer comparison, sets LatestEvent to null.

Passing an event that did not originate with this Subscription's channel, will lead to unpredictable behaviour

Close ( ) : void

Closes this Subscription, cancelling the consumer record in the server.

Nack ( RabbitMQ.Client.Events.BasicDeliverEventArgs evt, bool multiple, bool requeue ) : void

If we are not in "autoAck" mode, calls IModel.BasicNack with the delivery-tag from evt; otherwise, sends nothing to the server. if evt is the same as LatestEvent by pointer comparison, sets LatestEvent to null.

Passing an event that did not originate with this Subscription's channel, will lead to unpredictable behaviour

Nack ( bool requeue ) : void

If LatestEvent is non-null, passes it to Nack(BasicDeliverEventArgs, false, requeue). Causes LatestEvent to become null.

Nack ( bool multiple, bool requeue ) : void

If LatestEvent is non-null, passes it to Nack(BasicDeliverEventArgs, multiple, requeue). Causes LatestEvent to become null.

Next ( ) : RabbitMQ.Client.Events.BasicDeliverEventArgs

Retrieves the next incoming delivery in our subscription queue.

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 "autoAck" mode, the server will have auto-acknowledged each event before it is even sent across the wire to us).

Next ( int millisecondsTimeout, RabbitMQ.Client.Events.BasicDeliverEventArgs &result ) : bool

Retrieves the next incoming delivery in our subscription queue, or times out after a specified number of milliseconds.

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 "autoAck" 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).

NextAsync ( ) : Task
Subscription ( IModel model, string queueName ) : System

Creates a new Subscription in "autoAck" mode, consuming from a named queue.

Subscription ( IModel model, string queueName, bool autoAck ) : System

Creates a new Subscription, with full control over both "autoAck" mode and the name of the queue.

Subscription ( IModel model, string queueName, bool autoAck, string consumerTag ) : System

Creates a new Subscription, with full control over both "autoAck" mode, the name of the queue, and the consumer tag.

Protected Methods

Method Description
MutateLatestEvent ( RabbitMQ.Client.Events.BasicDeliverEventArgs value ) : void

Private Methods

Method Description
HandleConsumerCancelled ( object sender, RabbitMQ.Client.Events.ConsumerEventArgs e ) : void
IDisposable ( ) : void

Implementation of the IDisposable interface, permitting Subscription to be used in using statements. Simply calls Close().

IEnumerable ( ) : IEnumerator

Implementation of the IEnumerable interface, for permitting Subscription to be used in foreach loops.

IEnumerator ( ) : bool

Implementation of the IEnumerator interface, for permitting Subscription to be used in foreach loops.

Does not acknowledge any deliveries at all. Ack() must be called explicitly on received deliveries.

IEnumerator ( ) : void

Dummy implementation of the IEnumerator interface, for permitting Subscription to be used in foreach loops; Reset()ting a Subscription doesn't make sense, so this method always throws InvalidOperationException.

QueueAdd ( RabbitMQ.Client.Events.BasicDeliverEventArgs args ) : void

Method Details

Ack() public method

If LatestEvent is non-null, passes it to Ack(BasicDeliverEventArgs). Causes LatestEvent to become null.
public Ack ( ) : void
return void

Ack() public method

If we are not in "autoAck" mode, calls IModel.BasicAck with the delivery-tag from evt; otherwise, sends nothing to the server. if evt is the same as LatestEvent by pointer comparison, sets LatestEvent to null.
Passing an event that did not originate with this Subscription's channel, will lead to unpredictable behaviour
public Ack ( RabbitMQ.Client.Events.BasicDeliverEventArgs evt ) : void
evt RabbitMQ.Client.Events.BasicDeliverEventArgs
return void

Close() public method

Closes this Subscription, cancelling the consumer record in the server.
public Close ( ) : void
return void

MutateLatestEvent() protected method

protected MutateLatestEvent ( RabbitMQ.Client.Events.BasicDeliverEventArgs value ) : void
value RabbitMQ.Client.Events.BasicDeliverEventArgs
return void

Nack() public method

If we are not in "autoAck" mode, calls IModel.BasicNack with the delivery-tag from evt; otherwise, sends nothing to the server. if evt is the same as LatestEvent by pointer comparison, sets LatestEvent to null.
Passing an event that did not originate with this Subscription's channel, will lead to unpredictable behaviour
public Nack ( RabbitMQ.Client.Events.BasicDeliverEventArgs evt, bool multiple, bool requeue ) : void
evt RabbitMQ.Client.Events.BasicDeliverEventArgs
multiple bool
requeue bool
return void

Nack() public method

If LatestEvent is non-null, passes it to Nack(BasicDeliverEventArgs, false, requeue). Causes LatestEvent to become null.
public Nack ( bool requeue ) : void
requeue bool
return void

Nack() public method

If LatestEvent is non-null, passes it to Nack(BasicDeliverEventArgs, multiple, requeue). Causes LatestEvent to become null.
public Nack ( bool multiple, bool requeue ) : void
multiple bool
requeue bool
return void

Next() public method

Retrieves the next incoming delivery in our subscription queue.

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 "autoAck" mode, the server will have auto-acknowledged each event before it is even sent across the wire to us).

public Next ( ) : RabbitMQ.Client.Events.BasicDeliverEventArgs
return RabbitMQ.Client.Events.BasicDeliverEventArgs

Next() public method

Retrieves the next incoming delivery in our subscription queue, or times out after a specified number of milliseconds.

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 "autoAck" 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 Next ( int millisecondsTimeout, RabbitMQ.Client.Events.BasicDeliverEventArgs &result ) : bool
millisecondsTimeout int
result RabbitMQ.Client.Events.BasicDeliverEventArgs
return bool

NextAsync() public method

public NextAsync ( ) : Task
return Task

Subscription() public method

Creates a new Subscription in "autoAck" mode, consuming from a named queue.
public Subscription ( IModel model, string queueName ) : System
model IModel
queueName string
return System

Subscription() public method

Creates a new Subscription, with full control over both "autoAck" mode and the name of the queue.
public Subscription ( IModel model, string queueName, bool autoAck ) : System
model IModel
queueName string
autoAck bool
return System

Subscription() public method

Creates a new Subscription, with full control over both "autoAck" mode, the name of the queue, and the consumer tag.
public Subscription ( IModel model, string queueName, bool autoAck, string consumerTag ) : System
model IModel
queueName string
autoAck bool
consumerTag string
return System

Property Details

m_consumer protected_oe property

protected EventingBasicConsumer,RabbitMQ.Client.Events m_consumer
return RabbitMQ.Client.Events.EventingBasicConsumer

m_eventLock protected_oe property

protected object m_eventLock
return object